1. Manuals
  2. Brands
  3. Maker Factory Manuals
  4. Motherboard
  5. ELECTRONICS EXPERIMENTS BOX
  6. Manual

Maker Factory ELECTRONICS EXPERIMENTS BOX Manual

Hide thumbs
Table of Contents

Advertisement

Quick Links

Download this manual
15038-7_HB_U1_Eng.qxp_Layout 1 19.11.18 11:06 Seite 1

Advertisement

Table of Contents
loading
Need help?

Need help?

Do you have a question about the ELECTRONICS EXPERIMENTS BOX and is the answer not in the manual?

Questions and answers

Summary of Contents for Maker Factory ELECTRONICS EXPERIMENTS BOX

  • Page 1 15038-7_HB_U1_Eng.qxp_Layout 1 19.11.18 11:06 Seite 1...
  • Page 2 Electronics – Experiments Box All circuits and programmes presented in this book have been developed, tried and tested with the utmost care. However, errors cannot be fully excluded. Publisher and author are liable in cases of intent or gross negligence in accordance with statutory provisions. Other than that, publisher and author will only be liable for injury of life, body or health under the Product Liability Act or for the culpable infringement of fundamental contractual duties.
  • Page 3 Foreword Experiments should be fun, and this is at the foreground in this huge experimental package. We have more than 200 circuits – from very simple to rather complicated experiments. Some are just for action, while others might be potentially useful in house, yard or garden, but all of them will bring new expertise and skills.

  • Page 5: Table Of Contents

    Table of Contents The Experiment Box ....................11 What’s inside the experiment box ...............11 1.1.1 Breadboard ......................11 1.1.2 Transistors ......................11 1.1.3 Diodes ........................12 1.1.4 Solar cell ....................... 13 1.1.5 Ceramic capacitors ....................14 1.1.6 Electrolytic capacitors ................... 15 1.1.7 Fixed value inductance ..................16 1.1.8 Piezo element .......................
  • Page 6 2.13 Antenna amplifier ..................59 2.14 Acoustic continuity tester ................61 2.15 High pass ....................63 2.16 Electronic potentiometer ................66 2.17 Active battery monitor ................67 2.18 Two-stage AF amplifier ................69 2.19 Zener diode meter ..................70 2.20 Variable Zener diode ..................72 2.21 Acoustic Wellness –...
  • Page 7 2.47 Constant current source ................132 2.48 Hawaiian guitar ..................135 2.49 Glass breakage detector ................136 2.50 Trill generator ..................138 2.51 Iron-free push-pull amplifier ..............139 2.52 Flickering light ..................140 2.53 Sensor button (finger) ................141 2.54 Sensitive RF watchdog ................143 2.55 Electronic potentiometer ................
  • Page 8 2.81 AF switch ....................198 2.82 Voltage regulator ..................199 2.83 LC generator ....................204 2.84 Simple battery monitor ................206 2.85 Audio Fade-in and Fade-out ..............208 2.86 Level meter ....................209 2.87 Acoustic continuity tester ................211 2.88 Logic probe ....................212 2.89 Active probe ....................

  • Page 9: The Experiment Box

    1 The Experiment Box 1.1 What’s inside the experiment box 1.1.1 Breadboard All of the experiments are built on a convenient breadboard. The red lines demonstrate how the board is wired internally. Connectors of components and any jumper wires are simply inserted into the contacts. When finished with your experiment, pull out all the components and the wires.

  • Page 10: Diodes

    Fig. 1.4: The component symbol is on the left and for information, the circuit diagram symbol of the J111 FET-Transistors on the right; the experi- mental package contains one only. Fig. 1.5: The component symbol is on the left and for information, the circuit diagram symbol of the PT331C phototransistor on the right;...

  • Page 11: Solar Cell

    Fig. 1.8: The component symbol is on the left and for information, the circuit diagram symbol of the yellow LED on the right; the experimental package contains one only. Fig. 1.9: The component symbol is on the left and for information, the circuit diagram symbol of the infrared diode on the right;...

  • Page 12: Ceramic Capacitors

    1.1.5 Ceramic capacitors Ceramic capacitors are used for the separation of DC voltage and are mainly utilized with high frequencies. Fig. 1.13: The component symbol is on the left and for information, the circuit diagram symbol of the silicon solar cell on the right; the experimental package contains one only.

  • Page 13: Electrolytic Capacitors

    Fig. 1.18: The component symbol is on the left and for information, the circuit diagram symbol of the 100-nf ceramic capacitor on the right; the experimental package contains three of them. 1.1.6 Electrolytic capacitors Electrolytic capacitors are used for the separation of DC voltage and for short-term storage of electrical energy.

  • Page 14: Fixed Value Inductance

    Fig. 1.23: The component symbol is on the left and for information, the circuit diagram symbol of the 1.000-μF electrolytic capacitor on the right; the experimental package contains one only. 1.1.7 Fixed value inductance Inductors are mainly used in resonant circuits or for screening purposes. Fig.

  • Page 15: Battery Clip 9-V Block

    1.1.10 Battery clip 9-V block A battery clip is used to connect the battery to the circuit. Fig. 1.27: Component symbol of the enclosed battery clip for a 9 V block battery, there is no individual circuit diagram symbol for this; the experimental package contains one only.
  • Page 16 Fig. 1.31: The component symbol is on the left and for information, the circuit diagram symbol of the 47-Ω resistor on the right; the experimental package contains one only. Fig. 1.32: The component symbol is on the left and for information, the circuit diagram symbol of the 100-Ω...
  • Page 17 Fig. 1.36: The component symbol is on the left and for information, the circuit diagram symbol of the 2.2-kΩ resistor on the right; the experimental package contains three of them. Fig. 1.37: The component symbol is on the left and for information, the circuit diagram symbol of the 3.3-kΩ...
  • Page 18 Fig. 1.41: The component symbol is on the left and for information, the circuit diagram symbol of the 22-kΩ resistor on the right; the experimental package contains four of them. Fig. 1.42: The component symbol is on the left and for information, the circuit diagram symbol of the 47-kΩ...

  • Page 19: Moving-Coil Instrument

    Fig. 1.46: The component symbol is on the left and for information, the circuit diagram symbol of the 470-kΩ resistor on the right; the experimental package contains two of them. Fig. 1.47: The component symbol is on the left and for information, the circuit diagram symbol of the 1-MΩ...

  • Page 20: Tips

    1.2 Tips 1.2.1 Successful equipping A perfect connection is the alpha and omega for your experiment to succeed. But a problem with a contact in an electrical system brings even a car to a halt. Make sure that the jumper wires of components are all free of grease and dirt. The ends should be straight- ened.

  • Page 21: Moving-Coil Instrument

    Fig. 1.51: Acoustic panel 1.2.4 Moving-coil instrument A moving-coil instrument is fragile and easily damaged by higher voltage or current. If you do your own experiments, make sure that you always have a sufficiently sized series resistor installed. We use a 9V block battery in our experiments, a series resistor of 4.7 kΩ...

  • Page 22: Experiments

    2 Experiments In this chapter we will introduce 200 experiments. You don’t need any previous knowledge nor do you need to be able to read or understand circuit diagrams in order to have your experiments up working success- fully. You also don’t need to understand how individual components, work. Our experiments with bread- board and 9V battery are all safe for beginners.

  • Page 23: Series Connection

    2.1 Series connection Circuit 1: Simple voltage measurement Setup information Install the two resistors and then the jumper as shown in Fig. 2.1. Now connect the moving-coil instrument. Check the placement on the board again and only then connect the battery. Components required: 2 x 10 kΩ...
  • Page 24 Circuit 2: Extending the measuring range Setup information Install the resistor and then the jumper as shown in Fig. 2.2. Connect the moving-coil instrument. Check the placement on the board again and only then connect the battery. Components required: 1 x 10 kΩ resistor, 1 x moving-coil instrument, 1 x breadboard, 1 x 9V bat- tery with clip connector...
  • Page 25 Circuit 3: Forward and reverse bias Setup information Install the two resistors and then the Schottky diode. Take note of the forward current (black ring) of the diode. Then fit the jumper wire (Fig. 2.3) and connect the moving-coil instrument. Check the placement on the board again and only then connect the battery.
  • Page 26 Components required: 2 x 10 kΩ resistors, 1 x BAT85 Schottky diode, 1 x moving- coil instrument, 1 x breadboard, 1 x 9V battery with clip con- nector Fig. 2.3a: Diode in reverse direction Experiment Nothing happens after the battery has been connected. The needle of the moving-coil instrument is not moving.

  • Page 27: Parallel Connection

    2.2 Parallel connection Circuit 4: Current measurement without shunt resistance Setup information Install the two resistors and then the jumper as shown in Fig. 2.4. Then connect the moving-coil instru- ment. Check the placement on the board again and only then connect the battery. Components required: 2 x 10 kΩ...
  • Page 28 Circuit 5: Current measurement with a small shunt resistance Setup information Install the four resistors and then the jumper as shown in Fig. 2.5. Connect the moving-coil instrument. Check the placement on the board again and only then connect the battery. Components required: 2 x 10 kΩ...
  • Page 29 Circuit 6: Current measurement with a greater shunt resistance Setup information Install the three resistors and then the two jumpers as shown in Fig. 2.6. Connect the moving-coil instru- ment. Check the placement on the board again and only then connect the battery. Components required: 2 x 10 kΩ...

  • Page 30: Determining The Connection Sequence Of A Bipolar Transistor

    2.3 Determining the connection sequence of a bipolar transistor Circuit 7: Determining the connection sequence of a PNP transistor Setup information Install the transistor as shown in Fig. 2.7 followed by the resistors. Now it is time for the jumpers. For the purpose of identification, the measurement lines are shown in the figure in black or red.
  • Page 31 Circuit 8: Determining the connection sequence of a NPN transistor Setup information Install the transistor as shown in Fig. 2.8. After that, install all other resistors. Now it is time for the jump- ers. For the purpose of identification, the measuring leads are shown in the figure in black or red. Feel free to use your own colours.

  • Page 32: Determining The Current Amplification Of A Bipolar Transistor

    2.4 Determining the current amplification of a bipolar transistor Circuit 9: PNP transistor B test Setup information Install the transistor as shown in Fig. 2.9. Install all other resistors. Now it is time for the jumpers. Connect the moving-coil instrument. Check the placement on the board again and only then connect the battery. Components required: 1 x 2N3906 transistor, 1 x 1 MΩ...
  • Page 33 Circuit 10: NPN transistor B test Setup information Install the transistor as shown in Fig. 2.10. Install all other resistors. Now it is time for the jumpers. Connect the moving-coil instrument. Check the placement on the board again and only then connect the battery. Components required: 1 x 2N3904 transistor, 1 x 1 MΩ...

  • Page 34: Diodes

    2.5 Diodes Circuit 11: Threshold voltage silicone diode Setup information Install the diode as shown in Fig. 2.11. Install the two resistors. Now it is time for the jumpers. Connect the moving-coil instrument. Check the placement on the board again and only then connect the battery. Components required: 1 x 1N4148 silicon diode, 2 x 1 kΩ...
  • Page 35 Circuit 12: Threshold voltage Schottky diode Setup information Install the diode as shown in Fig. 2.12. Install the two resistors. Now it is time for the jumpers. Connect the moving-coil instrument. Check the placement on the board again and only then connect the battery. Components required: 1 x BAT 85 Schottky diode, 2 x 1 kΩ...
  • Page 36 Circuit 13: Threshold voltage red LED Setup information Install the diode as shown in Fig. 2.13. Install the two resistors. Now it is time for the jumpers. Connect the moving-coil instrument. Check the placement on the board again and only then connect the battery. Components required: 1 x red LED, 2 x 1 kΩ...
  • Page 37 Circuit 14: Threshold voltage green LED Setup information Install the diode as shown in Fig. 2.14. Install the two resistors. Now it is time for the jumpers. Connect the moving-coil instrument. Check the placement on the board again and only then connect the battery. Components required: 1 x green LED, 2 x 1 kΩ...
  • Page 38 Circuit 15: Threshold voltage yellow LED Setup information Install the diode as shown in Fig. 2.15. Install the two resistors. Now it is time for the jumpers. Connect the moving-coil instrument. Check the placement on the board again and only then connect the battery. Components required: 1 x yellow LED, 2 x 1 kΩ...
  • Page 39 Circuit 16: Threshold voltage infrared diode Setup information Install the diode as shown in Fig. 2.16. Install the two resistors. Now it is time for the jumpers. Connect the moving-coil instrument. Check the placement on the board again and only then connect the battery. Components required: 1 x Infrared diode, 2 x 1 kΩ...

  • Page 40: Double Turn Signals

    2.6 Double turn signals Circuit 17: Awesome double turn signals Setup information Install the two transistors as shown in Fig. 2.17. Install the two light-emitting diodes. Now it is time for the six resistors. Finally insert the eight jumpers. Check the placement on the board again and only then con- nect the battery.
  • Page 41 Circuit 18: Boring double turn signals Setup information Install the two transistors as shown in Fig. 2.18. Install the two LEDs. Now it is time for the six resistors. Finally insert the eight jumpers. Check the placement on the board again and only then connect the battery. Components required: 2 x 2N3904 transistors, 1 x red LED, 1 x green LED,...

  • Page 42: Binary Memory

    2.7 Binary memory Circuit 19: An electronic brain cell Setup information Install the two transistors as shown in Fig. 2.19. Then install the green LED. Now it is time for the six resis- tors. Finally insert the five jumpers and the two jumpers which will function as switches (shown in dashed lines to identify them easily).
  • Page 43 Circuit 20: A bell with a memory You can connect the circuit to a standard bell button and a gong. Setup information Install the two transistors as shown in Fig. 2.20. Then install the green LED. Now it is time for the six resis- tors.

  • Page 44: Flashing Bicycle Light

    2.8 Flashing bicycle light Circuit 21: Flashing tail light Setup information Install the two transistors as shown in Fig. 2.21. Install the two red LEDs. Now it is time for the four resistors and the two electrolytic capacitors. Finally Insert the six jumpers. The circuit could be used as flashy bike tail light if the assembly is somehow water-resistant.
  • Page 45 Circuit 22: Flashing bicycle light Setup information Install the two transistors as shown in Fig. 2.22. Install the two white LEDs. If you do not have white LEDs, use a green and a yellow instead. Now it is time for the four resistors and the two electrolytic capacitors. Finally, insert the six jumper wires.

  • Page 46: Solar Light

    2.9 Solar light Circuit 23: Simple solar light Setup information Install the two diodes as shown in Fig. 2.23. Then install the resistor. Finally connect the solar cell. Components required: 1 x solar cell, 1 x red LED, 1 x BAT85 Schottky diode, 1 x 220 Ω...
  • Page 47 Circuit 24: Solar light with battery Setup information Install the two diodes as shown in Fig. 2.24. Then install the resistor and connect the two AA battery holders. Finally connect the solar cell. Check the placement on the board again and only then connect the rechargeable batteries.
  • Page 48 Here is a little experiment on the sidelines: If you remove the red LED from the circuit, you will get a small solar charger for two AA NiMH batteries. The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.24. Circuit 25: Automatic solar light with battery Setup information Install the transistor and the two diodes as shown in Fig.

  • Page 49: Switch-Off Delay

    at night. During charging, that is, when the sun is shining, the transistor turns the LED off. The transistor switches the red LED on as soon as it is getting dark. The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.25. 2.10 Switch-off delay Circuit 26: 2 seconds switch-off delay Setup information...
  • Page 50 Circuit 27: 4 seconds switch-off delay Setup information Install the two transistors and the two diodes as shown in Fig. 2.27. Then install the four resistors and the electrolytic capacitor. The seven jumpers come next. The jumper acting as the switch (shown dashed) is installed last. Only one end of the jumper wire is con- nected, the other is open.
  • Page 51 Circuit 28: 20 seconds switch-off delay Setup information Install the two transistors and the two diodes as shown in Fig. 2.28. Then install the four resistors and the electrolytic capacitor. The seven jumpers come next. The jumper acting as the switch (shown dashed) is installed last. Only one end of the jumper wire is con- nected, the other is open.

  • Page 52: Bicycle Light

    2.11 Bicycle light Circuit 29: Simple bicycle light Setup information Install the transistor and the two diodes as shown in Fig. 2.29. Then install the three resistors and the electrolytic capacitor. The seven jumper wires come next. The the jumper acting as switch (shown dashed) is installed last.
  • Page 53 Circuit 30: Automatic bicycle light with solar cell Setup information Install the transistor and the two diodes as shown in Fig. 2.30. Then install the three resistors and the electrolytic capacitor. The six jumper wires come next. The solar cell is installed last. Check the placement on the board again and only then connect the battery.
  • Page 54 Circuit 31: Automatic bicycle light with phototransistor Setup information Install the two transistors as shown in Fig. 2.31. Then the two resistors and the electrolytic capacitor are installed. The five jumper wires come next. Check the placement on the board again and only then connect the battery.

  • Page 55: Peak-Vu Meter

    2.12 Peak-VU meter Circuit 32: Simple peak VU meter with LED Setup information Install the transistor and the two diodes as shown in Fig. 2.32. Then install the three resistors and the elec- trolytic capacitor. The two jumper wires come next. Check the placement on the board again and only then connect the battery.
  • Page 56 Circuit 33: Peak VU meter with coil-moving instrument Setup information Install the transistor and the diode as shown in Fig. 2.33. Then install the three resistors and the electro- lytic capacitor. The three jumper wires come next. Check the placement on the board again and only then connect the battery.

  • Page 57: Antenna Amplifier

    2.13 Antenna amplifier Circuit 34: LM antenna amplifier for antennas with longer wires Setup information Install the transistor and the two resistors as shown in Fig. 2.34. Then install the two ceramic capacitors. The three jumper wires come next. Check the placement on the board again and only then connect the bat- tery.
  • Page 58 Circuit 35: LM antenna amplifier for antennas with short wires Setup information Install the two transistors and the four resistors as shown in Fig. 2.35. Then install the three ceramic capaci- tors. The six jumper wires come next. Check the placement on the board again and only then connect the battery.

  • Page 59: Acoustic Continuity Tester

    2.14 Acoustic continuity tester Circuit 36: Acoustic continuity tester Setup information Install the two transistors and the four resistors as shown in Fig. 2.36. Then install the two electrolytic capacitors and the four resistors followed by the eight jumpers. Finally connect the Piezo element. Check the placement on the board again and only then connect the battery.
  • Page 60 Circuit 37: Diode tester Setup information Install the two transistors, the diode and the four resistors as shown in Fig. 2.37. Install the two ceramic capacitors and the electrolytic capacitor followed by nine jumper wires. Finally connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 61: High Pass

    2.15 High pass Circuit 38: High pass 650 Hz onwards Setup information Install the transistor and the three resistors as shown in Fig. 2.38. Then install the two ceramic capacitors and the electrolytic capacitor. The five jumper wires come next. Finally Connect the Piezo element. Check the placement on the board again and only then connect the battery.
  • Page 62 Circuit 39: High pass 2.5 kHz onwards Setup information Install the transistor and the three resistors as shown in Fig. 2.39. Then install the two ceramic capacitors and the electrolytic capacitor. The five jumper wires come next. Finally connect the Piezo element. Check the placement on the board again and only then connect the battery.
  • Page 63 Circuit 40: High pass from on 5.5 kHz Setup information Install the transistor and the three resistors as shown in Fig. 2.40. Then install the two ceramic capacitors and the electrolytic capacitor. The five jumper wires come next. Finally connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 64: Electronic Potentiometer

    2.16 Electronic potentiometer Circuit 41: Electronic level control with large control range Setup information Install the two transistors and the five resistors as shown in Fig. 2.41. Then install the ceramic capacitor and the two electrolytic capacitors, followed by the eight jumper wires. Finally connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 65: Active Battery Monitor

    2.17 Active battery monitor Circuit 42: Active 8.5V battery monitor Setup information Install the two transistors, the two diodes and the eight resistors as shown in Fig. 2.42. Then install the two electrolytic capacitors. The fourteen jumper wires come next. Check the placement on the board again and only then connect the battery.
  • Page 66 Circuit 43: Active 7.8V battery monitor Setup information Install the two transistors, the LED and the nine resistors as shown in Fig. 2.43. Then install the two elec- trolytic capacitors. The fourteen jumper wires come next. Check the placement on the board again and only then connect the battery.

  • Page 67: Two-Stage Af Amplifier

    2.18 Two-stage AF amplifier Circuit 44: Two-stage AF preamplifier Setup information Install the two transistors and the six resistors as shown in Fig. 2.44. Then install the three electrolytic capacitors. The seven jumper wires come next. Finally connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 68: Zener Diode Meter

    2.19 Zener diode meter Circuit 45: Meters for 4.7 V Zener diodes and higher Setup information Install the two transistors and the three resistors as shown in Fig. 2.45. The seven jumper wires come next. Last but not least connect the moving-coil instrument. Check the placement on the board again and only then connect the battery.
  • Page 69 Circuit 46: Meters for 1.5 V Zener diodes and higher Setup information Install the two transistors and the three resistors as shown in Fig. 2.46. The seven jumper wires come next. Last but not least connect the moving-coil instrument. Check the placement on the board again and only then connect the battery.

  • Page 70: Variable Zener Diode

    2.20 Variable Zener diode Circuit 47: Discreet 2.2V Zener diode Setup information Install the two transistors and the six resistors as shown in Fig. 2.47. The ten jumper wires come next. Last but not least connect the moving-coil instrument. Check the placement on the board again and only then connect the battery.
  • Page 71 Circuit 48: Discreet 2.9V Zener diode Setup information Install the two transistors and the seven resistors as shown in Fig. 2.48. The nine jumper wires come next. Last but not least connect the moving-coil instrument. Check the placement on the board again and only then connect the battery.
  • Page 72 Circuit 49: Discreet 3.7V Zener diode Setup information Install the two transistors and the seven resistors as shown in Fig. 2.49. The nine jumper wires come next. Last but not least connect the moving-coil instrument. Check the placement on the board again and only then connect the battery.
  • Page 73 Circuit 50: Discreet 4.4V Zener diode Setup information Install the two transistors and the eight resistors as shown in Fig. 2.50. The nine jumper wires come next. Last but not least connect the moving-coil instrument. Check the placement on the board again and only then connect the battery.

  • Page 74: Acoustic Wellness - Ticking Clock

    2.21 Acoustic Wellness – ticking clock Circuit 51: Relaxing pendulum clock Setup information Install the two transistors, the three resistors and the two electrolytic capacitors as shown in Fig. 2.51. The five jumper wires come next. Last but not least, connect the Piezo element. Check the placement on the board again and only then connect the battery.
  • Page 75 Circuit 52: Stimulating mantel clock Setup information Install the two transistors, the three resistors and the two electrolytic capacitors as shown in Fig. 2.52. The five jumper wires come next. Last but not least, connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 76: Light Sensitive Switch

    2.22 Light sensitive switch Circuit 53: Light sensitive switch with green LED Setup information Install the two transistors, the two diodes and the two resistors as shown in Fig. 2.53. The three jumper wires come next. Check the placement on the board again and only then connect the battery. Components required: 2 x 2N3904 transistors, 1 x green LED, 1 x red LED,...
  • Page 77 Circuit 54: Light sensitive switch with solar cell Setup information Install the two transistors, the LED and the two resistors as shown in Fig. 2.54. The three jumper wires come next. Last but not least connect the solar cell. Check the placement on the board again and only then connect the battery.
  • Page 78 Circuit 55: Light sensitive switch with phototransistor Setup information Install the three transistors, the LED and the two resistors as shown in Fig. 2.55. The five jumper wires come next. Check the placement on the board again and only then connect the battery. Components required: 2 x 2N3904 transistors, 1 x PT331C phototransistor,...

  • Page 79: Symmetric Nf Limiter

    2.23 Symmetric NF Limiter Circuit 56: Audio limiter Setup information Install the two transistors and the six resistors as shown in Fig. 2.56. Next install the three electrolytic capacitors followed by the nine jumper wires. Finally connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 80: Storm Detector

    2.24 Storm detector Circuit 57: Amplifier for a storm detector Setup information Install the two transistors and the four resistors as shown in Fig. 2.57. Next install the three electrolytic capacitors followed by the six jumper wires. Finally connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 81: Active Dc-Dc Converter

    2.25 Active DC-DC converter Circuit 58: DC-DC converter 9V to 18V with coil-moving instrument Setup information Install the two transistors, the two diodes and the five resistors as shown in Fig. 2.58. Next, install the ceramic capacitor, the electrolytic capacitor and the fixed inductance. Make sure that the electrolytic capaci- tor has a dielectric strength of 160V.
  • Page 82 Circuit 59: DC-DC converter 9V to 35V with LED Setup information Install the two transistors, the two diodes and the four resistors as shown in Fig. 2.59. Next, install the ceramic capacitor, the electrolytic capacitor and the fixed inductance. Make sure that the electrolytic capaci- tor has a dielectric strength of 160V.
  • Page 83 Circuit 60: DC-DC converter 9V to 35V with coil-moving instrument Setup information Install the two transistors, the diode and the four resistors as shown in Fig. 2.60 followed by the ceramic capacitor, the electrolytic capacitor and the fixed value inductor. It is important to make sure that the elec- trolytic capacitor has a dielectric strength of 160V.
  • Page 84 Circuit 61: DC-DC converter 9V to 55V with LED Setup information Install the two transistors, the two diodes and the four resistors as shown in Fig. 2.61. Next, install the ceramic capacitor, the electrolytic capacitor and the fixed inductance. Make sure that the electrolytic capacitor has a dielectric strength of 160V. The thirteen jumper wires come next.
  • Page 85 Circuit 62: DC-DC converter 9V to 75V Setup information Install the two transistors, the diode and the three resistors as shown in Fig. 2.62. Next install the ceramic capacitor, the electrolytic capacitor and the fixed value inductor. It is important to ensure that the electro- lytic capacitor has a dielectric strength of 160V.

  • Page 86: Low Regulated Output Voltage

    2.26 Low regulated output voltage Circuit 63: Stabilizer for 1.0 V Setup information Install the three transistors and the four resistors as shown in Fig. 2.63. Next come the 11 jumper wires. Check the placement on the board again and only then connect the battery. Components required: 1 x 2N3906 transistor, 2 x 2N3904 transistors,...
  • Page 87 Circuit 64: Stabilizer for 1.9 V Setup information Install the three transistors and the four resistors as shown in Fig. 2.64. Next come the eleven jumper wires. Check the placement on the board again and only then connect the battery. Components required: 1 x 2N3906 transistor, 2 x 2N3904 transistors,...
  • Page 88 Circuit 65: Stabilizer for 2.5 V Setup information Install the three transistors and the four resistors as shown in Fig. 2.65. Next come the eleven jumper wires. Check the placement on the board again and only then connect the battery. Components required: 1 x 2N3906 transistor, 2 x 2N3904 transistors,...

  • Page 89: Schmitt-Trigger

    2.27 Schmitt-Trigger Circuit 66: Schmitt trigger circuit with 4V hysteresis. Setup information Install the three transistors, the LED and the six resistors as shown in Fig. 2.66. Next are the 11 jumper wires. Check the placement on the board again and only then connect the battery. Components required: 2 x 2N3904 transistors, 1 x 2N3906 transistor,...
  • Page 90 Circuit 67: Schmitt trigger with 2V hysteresis Setup information Install the three transistors, the diode and the six resistors as shown in Fig. 2.67. Next are the 11 jumper wires. Check the placement on the board again and only then connect the battery. Components required: 2 x 2N3904 transistors, 1 x 2N3906 transistor,...

  • Page 91: Turn Signal Gentle To The Eye

    2.28 Turn signal gentle to the eye Circuit 68: LED blinker 1 Hz Setup information Install the two transistors, the diode and the five resistors as shown in Fig. 2.68. Then install the three electrolytic capacitors. The 13 jumper wires are next. Check the placement on the board again and only then connect the battery.
  • Page 92 Circuit 69: LED blinker 3 Hz Setup information Install the two transistors, the diode and the five resistors as shown in Fig. 2.69. Then install the three electrolytic capacitors. The 13 jumper wires are next. Check the placement on the board again and only then connect the battery.

  • Page 93: Riaa Equalizer

    2.29 RIAA equalizer Circuit 70: RIAA equalizer Setup information Install the three transistors, the eight resistors and the two ceramic capacitors as shown in Fig. 2.70. Install the three electrolytic capacitors. The 18 jumper wires are next. Finally connect the Piezo element. Check the placement on the board again and only then connect the battery.
  • Page 94 Circuit 71: low-noise preamplifier Setup information Install the two transistors, the three resistors and the two electrolytic capacitors as shown in Fig. 2.71. The six jumper wires come next. Last but not least connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 95: Low Pass

    2.30 Low pass Circuit 72: RC low pass 1.5 kHz Setup information Install the transistor and the electrolytic capacitor as shown in Fig. 2.72. Last but not least, connect the Piezo element. Check the placement on the board again. You can significantly increase the sensitivity of the Piezo element by using a sound plate or even a sound box.
  • Page 96 Circuit 73: RC low pass 3 kHz Setup information Install the transistor and the electrolytic capacitor as shown in Fig. 2.73. Last but not least, connect the Piezo element. Check the placement on the board again. You can significantly increase the sensitivity of the Piezo element by using a sound plate or even a sound box.
  • Page 97 Circuit 74: LC low pass 3.4 kHz Setup information Install the fixed value inductor and the electrolytic capacitor as shown in Fig. 2.74. Then Connect the Piezo element. Check the placement on the board again. You can significantly increase the sensitivity of the Piezo element by using a sound plate or even a sound box.
  • Page 98 Circuit 75: RC high pass 160 Hz Setup information Install the transistor and the electrolytic capacitor as shown in Fig. 2.75. Last but not least, connect the Piezo element. Check the placement on the board again. You can significantly increase the sensitivity of the Piezo element by using a sound plate or even a sound box.
  • Page 99 Circuit 76: High pass from on 1.6 kHz Setup information Install the transistor and the electrolytic capacitor as shown in Fig. 2.76. Last but not least, connect the Piezo element. Check the placement on the board again. You can significantly increase the sensitivity of the Piezo element by using a sound plate or even a sound box.
  • Page 100 Circuit 77: LC low pass 3.4 kHz Setup information Install the fixed value inductor and the electrolytic capacitor as shown in Fig. 2.77. Then connect the Piezo element. Check the placement on the board again. You can significantly increase the sensitivity of the Piezo element by using a sound plate or even a sound box.

  • Page 101: Quiztimer

    2.31 Quiztimer Circuit 78: Quiztimer 3 seconds Setup information Install the two transistors, the diode and the four resistors as shown in Fig. 2.78. The seven jumper wires come next. Finally, insert the six jumper wire, which will function as a switch (shown dashed). Check the placement on the board again and only then connect the battery.
  • Page 102 Circuit 79: Quiztimer 8 seconds Setup information Install the two transistors, the diode and the four resistors and the two electrolytic capacitors as shown in Fig. 2.79. The nine jumper wires come next. Finally, insert the jumper wire, which will function as a switch (shown dashed).
  • Page 103 Circuit 80: Quiztimer 30 seconds Setup information Install the two transistors, the diode and the four resistors as shown in Fig. 2.80. The seven jumper wires come next. Finally, insert the six jumper wires, which will function as a switch (shown dashed). Check the placement on the board again and only then connect the battery.

  • Page 104: Handy Diode Tester

    2.32 Handy diode tester Circuit 81: Handy diode tester Setup information Install the transistor, the diode and the two resistors as shown in Fig. 2.81. The three jumper wires come next. Check the placement on the board again and only then connect the battery. Components required: 1 x 2N3904 transistor, 1 x green LED, 1 x 1 Ω...
  • Page 105 Circuit 82: Handy diode tester with moving-coil instrument Setup information Install the transistor and the two resistors as shown in Fig. 2.82 followed by the three jumper wires. Last but not least connect the moving-coil instrument. Check the placement on the board again and only then connect the battery.

  • Page 106: E-Cap As Crystal Diode

    2.33 E-cap as crystal diode Circuit 83: Electrolytic capacitor lets direct current pass through Setup information Install the diode and the three electrolytic capacitors as shown in Fig. 2.83. The two jumper wires are next. Check the placement on the board again and only then connect the battery. Components required: 1 x red LED, 1 x 10 μF electrolytic capaci-...
  • Page 107 Circuit 84: Electrolytic capacitor blocking direct current Setup information Install the diode and the electrolytic capacitor as shown in Fig. 2.84. The two jumper wires are next. Check the placement on the board again and only then connect the battery. Components required: 1 x red LED, 1 x 10 μF electrolytic capacitor,...

  • Page 108: Fog Horn

    2.34 Fog horn Circuit 85: Fog horn Setup information Install the two transistors, the five resistors and the two electrolytic capacitors as shown in Fig. 2.85. The nine jumper wires come next. Last but not least, connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 109: Mosquito Repeller

    2.35 Mosquito repeller Circuit 86: Mosquito repeller Setup information Install the two transistors, the four resistors and the three electrolytic capacitors as shown in 2.86 followed by the eight jumper wires. Last but not least connect the Piezo element. Check the placement on the board again and only then connect the battery. Components required: 2 x 2N3904 transistors, 2 x 1 kΩ...

  • Page 110: Metronome

    2.36 Metronome Circuit 87: Metronome with discreet unijunction transistor Setup information Install the two transistors, the four resistors and the two electrolytic capacitors as shown in Fig. 2.87. The nine jumper wires come next. Last but not least connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 111: Constant Current Sources For Leds

    2.37 Constant current sources for LEDs Circuit 88: constant current with FET transistor Setup information Install the FET transistor and the three diodes as shown in Fig. 2.88. The three jumper wires are next. Check the placement on the board again and only then connect the battery. Components required: 1 x J111 FET transistor, 1 x red LED, 1 x green...
  • Page 112 Circuit 89: constant current with FET transistor Setup information Install the FET transistor, the LED diode and the silicon diode as shown in Fig. 2.89. Then install the resis- tor. The three jumper wires come next. Check the placement on the board and only then connect the bat- tery.
  • Page 113 Circuit 90: Constant current with bipolar transistor Setup information Install the two transistors, the LED diode and the silicon diode as shown in Fig. 2.90. Then install the resis- tor. The seven jumper wires come next. Check the placement on the board and only then connect the bat- tery.
  • Page 114 Circuit 91: Constant current with bipolar transistor Setup information Install the two transistors and the three resistors and the LED diodes as shown in Fig. 2.91. The six jumper wires are next. Check the placement on the board again and only then connect the battery. Components required: 1 x J111 FET transistor, 1 x 2N3904 transistor,...

  • Page 115: Fireworks

    2.38 Fireworks Circuit 92: LED firework Setup information Install the two transistors, the three LEDs from your experiment box, the four resistors and the two electro- lytic capacitors as shown in Fig. 2.92. If you find another LED in your own hobby box such as a red one, go ahead and use it.

  • Page 116: Bursts Of Light

    The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.92. 2.39 Bursts of light Circuit 93: Fast LED flash Setup information Install the two transistors, the LED, the three resistors and the two electrolytic capacitors as shown in Fig.
  • Page 117 Circuit 94: Slow LED flash Setup information Install the two transistors, the LED, the three resistors and the three electrolytic capacitors as shown in Fig. 2.94. The ten jumper wires come next. Check the placement on the board again and only then connect the battery.

  • Page 118: Loud Foghorn

    2.40 Loud foghorn Circuit 95: Fog horn Setup information Install the three transistors, the seven resistors and the two electrolytic capacitors as shown in Fig. 2.95. The twelve jumper wires come next. Finally connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 119: Chaotic Flashing

    2.41 Chaotic flashing Circuit 96: Two LED in Waltz time Setup information Install the two transistors, the two LEDs, the four resistors and the three electrolytic capacitors as shown in Fig. 2.96. Finally, insert the 13 jumper wires. Check the placement on the board and only then connect the battery.
  • Page 120 Circuit 97: A needle fidgets in waltz time Setup information Install the two transistors, the LED, the four resistors and the three electrolytic capacitors as shown in Fig. 2.97 Then connect the moving-coil instrument. Finally, insert the 13 jumper wires. Check the placement on the board again and only then connect the battery.

  • Page 121: Led Driver

    2.42 LED driver Circuit 98: Constant current supply for LEDs Setup information Install the transistor, the diode and the two resistors as shown in Fig. 2.98. Then install the three jumper wires. Check the placement on the board again and only then connect the battery. Components required: 1 x 2N3904 transis- tor, 2 x 1N4148 silicon...
  • Page 122 Circuit 99: Constant current supply for LEDs Setup information Install the transistor, the diode and the two resistors as shown in Fig. 2.99. Then install the three jumper wires. Check the placement on the board again and only then connect the battery. Components required: 1 x 2N3904 transis- tor, 2 x 1N4148 silicon...

  • Page 123: Electronic Potentiometer

    2.43 Electronic potentiometer Circuit 100: Electronic potentiometer Setup information Install the two transistors, the diode, the four resistors and the two electrolytic capacitors as shown in Fig. 2.100 followed by the eight jumper wires. Last but not least connect the Piezo element. Check the place- ment on the board again and only then connect.

  • Page 124: Battery Charger

    2.44 Battery charger Circuit 101: Charge circuit for AA batteries Setup information Install the transistor, the three diodes and the two resistors as shown in Fig. 2.101. Then install the three jumper wires. Finally connect the AA battery holder. Check the placement on the board again and only then connect the battery.
  • Page 125 Circuit 102: Charge circuit for AA batteries Setup information Install the transistor, the three diodes and the two resistors as shown in Fig. 2.102. Then install the three jumper wires. Finally connect the AA battery holder. Check the placement on the board again and only then connect the battery.

  • Page 126: Battery Discharger

    2.45 Battery discharger Circuit 103: Discharge circuit for AA batteries Setup information Install the transistor, the two diodes and the two resistors as shown in Fig. 2.103. Then install the three jumper wires. Finally connect the AA battery holder Check the placement on the board again and only then connect the battery.
  • Page 127 Circuit 104: Discharge circuit for AA batteries Setup information Install the transistor, the two diodes and the two resistors as shown in Fig. 2.104. Then install the three jumper wires. Finally connect the AA battery holder Check the placement on the board again and only then connect the battery.

  • Page 128: Whistle Buoy

    2.46 Whistle buoy Circuit 105: Whistle buoy Setup information Install the two transistors, the five resistors, the ceramic capacitor and the electrolytic capacitor as shown in Fig. 2.105.The ten jumper wires come next. Finally, insert one end of the jumper wire, which will function as switch (shown dashed) and is labelled with Start.
  • Page 129 Circuit 106: Whistle buoy Setup information Install the two transistors, the five resistors, the ceramic capacitor and the electrolytic capacitor as shown in Fig. 2.106. The ten jumper wires come next. Finally, insert one end of the jumper wire, which will function as switch (shown dashed) and is labelled with Start.

  • Page 130: Constant Current Source

    2.47 Constant current source Circuit 107: constant current source 1.2 mA Setup information Install the two transistors and the six resistors as shown in Fig. 2.107. Then insert the eight jumpers. Check the placement on the board again and only then connect the battery. Components required: 2 x 2N3904 transistors, 1 x 47 Ω...
  • Page 131 Circuit 108: Constant current source 2 mA Setup information Install the two transistors and the five resistors as shown in Fig. 2.108. The nine jumper wires are next. Check the placement on the board again and only then connect the battery. Components required: 2 x 2N3904 transistors, 1 x 47 Ω...
  • Page 132 Circuit 109: Constant current source 5.7 mA Setup information Install the two transistors and the four resistors as shown in Fig. 2.109. The eight jumpers are next. Check the placement on the board again and only then connect the battery. Components required: 2 x 2N3904 transistors, 1 x 47 Ω...

  • Page 133: Hawaiian Guitar

    2.48 Hawaiian guitar Circuit 110: Hawaiian guitar Setup information Install the two transistors, the two resistors, the ceramic capacitor and the electrolytic capacitor as shown in Fig. 2.110 The seven jumper wires come next. Last but not least connect the Piezo element and the external resistor R1.

  • Page 134: Glass Breakage Detector

    2.49 Glass breakage detector Circuit 111: Glass breakage detector Setup information Install the three transistors, the diode and the six resistors as shown in Fig. 2.111 The twelve jumper wires come next. Last but not least connect the Piezo element. Check the placement on the board again and only then connect the battery.
  • Page 135 Circuit 112: Glass breakage detector Setup information Install the three transistors, the diode and the six resistors as shown in Fig. 2.112 The twelve jumper wires come next. Last but not least connect the Piezo element. Check the placement on the board again and only then connect.

  • Page 136: Trill Generator

    2.50 Trill generator Circuit 113: Trill generator Setup information Install the transistor, the seven resistors and the three ceramic capacitors and the electrolytic capacitors as shown in Fig. 2.113 The twelve jumper wires come next and then the jumper, which will function as a switch (shown dashed).

  • Page 137: Iron-Free Push-Pull Amplifier

    2.51 Iron-free push-pull amplifier Circuit 114: Iron-free push-pull amplifier Setup information Install the three transistors, the two diodes, the four resistors and the two electrolytic capacitors as shown in Fig. 2.114 Followed by the 14 jumper wires. Last but not least, connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 138: Flickering Light

    2.52 Flickering light Circuit 115: Flickering light Setup information Install the two transistors, the LED, the six resistors and the electrolytic capacitor as shown in Fig. 2.115. Finally, insert the eleven jumper wires. Check the placement on the board again and only then connect the battery.

  • Page 139: Sensor Button (Finger)

    2.53 Sensor button (finger) Circuit 116: On button with sensor Setup information Install the two transistors, the LED diode and the five resistors as shown in Fig. 2.116. Finally, insert the six jumper wires. Check the placement on the board again and only then connect the battery. Components required: 1 x J111 FET transistor, 1 x 2N3904 transistor,...
  • Page 140 Circuit 117: Off button with sensor Setup information Install the two transistors, the LED diode and the ten resistors as shown in Fig. 2.117. Finally, insert the 11 jumper wires. Check the placement on the board again and only then connect the battery. Components required: 1 x J111 FET transistor, 2 x 2N3904 transistors,...

  • Page 141: Sensitive Rf Watchdog

    2.54 Sensitive RF watchdog Circuit 118: RF watchdog with LED indicator Setup information Install the two transistors, the two diodes, the eight resistors and the three ceramic capacitors as shown in Fig. 2.118 Finally, insert the ten jumper wires. Check the placement on the board and only then connect the battery.
  • Page 142 Circuit 119: RF watchdog with moving-coil instrument. Setup information Install the two transistors, the diode, the eight resistors and the three ceramic capacitors as shown in Fig. 2.119 Connect the moving-coil instrument. Finally, insert the ten jumper wires. Check the placement on the board again and only then connect the battery.

  • Page 143: Electronic Potentiometer

    2.55 Electronic potentiometer Circuit 120: Electronic level control Setup information Install the two transistors, the three resistors and the two electrolytic capacitors as shown in Fig. 2.120 followed by a jumper wire. Check the placement on the board again before you start with your experiment and only then connect the battery.

  • Page 144: Sensor Toggle Switch (Finger)

    2.56 Sensor toggle switch (finger) Circuit 121: Sensor toggle switch with LED Setup information Install the three transistors, the diode and the six resistors as shown in Fig. 2.121. Finally insert the eight jumpers and the two jumpers used as switches (shown dashed). For your guidance we have labelled the “switches”...
  • Page 145 Circuit 122: Sensor toggle switch with LED Setup information Install the three transistors and the six resistors as shown in Fig. 2.122. Finally, insert the seven jumper wires two jumpers used as switches (shown dashed). For your guidance we have labelled the “switches” with “Tab On”...

  • Page 146: Voltage Multiplier Passive

    The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.122. 2.57 Voltage multiplier passive Circuit 123: Voltage doubler with moving-coil instrument Setup information Install the two diodes, the two electrolytic capacitors and the resistor as shown in Fig. followed by the 2.123 three jumper wires.
  • Page 147 Circuit 124: Voltage quadrupler with moving-coil instrument Setup information Install the two transistors, the two diodes, the four electrolytic capacitors and the transistor as shown in Fig. 2.124. Finally, insert the nine jumper wires. Check the placement on the board again. If you are familiar with the relevant safety guidelines as per VDE and know how to observe them when working with devices that are to be connected to the mains, you can now connect the transformer.

  • Page 148: Solar Charger

    2.58 Solar charger Circuit 125: Solar charger for AA battery Setup information Install the diode as shown in Fig. 2.125. Connect the solar cell and the AA battery holder. Check the place- ment on the board again. Components required: 1 x solar cell, 1 x BAT85 Schottky diode, 1 x breadboard, 1 x AA battery holder...
  • Page 149 Circuit 126: Solar charger for two AA batteries Setup information Install the diode as shown in Fig. 2.126. Connect the solar cell and the two AA battery holders. Check the placement on the board again. Components required: 1 x solar cell, 1 x BAT85 Schottky diode, 1 x breadboard, 2 x AA battery holders Fig.

  • Page 150: Electronic Drum

    2.59 Electronic drum. Circuit 127: Electronic drum Setup information Install the three transistors, the three, transistors, the eleven resistors, the four ceramic capacitors and the two electrolytic capacitors as shown in Fig. 2.127. The 20 jumper wires come next followed by the jumper, which will function as a switch (shown dashed).

  • Page 151: Switch-On Delay

    2.60 Switch-on delay Circuit 128: Switch on delay 0.5 seconds Setup information Install the two transistors, the diode, the three resistors and the electrolytic capacitor as shown in Fig. 2.128 The six jumper wires come next followed by the jumper, which serves as a switch (shown dashed). For your guidance, we labelled the “switch”...
  • Page 152 Circuit 129: 2 seconds switch-on delay Setup information Install the two transistors, the diode, the three resistors and the electrolytic capacitor as shown in Fig. 2.129 The six jumper wires come next followed by the jumper, which serves as a switch (shown dashed). For your guidance, we labelled the “switch”...
  • Page 153 Circuit 130: 4 seconds switch-on delay Setup information Install the two transistors, the diode, the three resistors and the electrolytic capacitor as shown in Fig. 2.130 The six jumper wires come next followed by the jumper, which serves as a switch (shown dashed). For your guidance, we labelled the “switch”...
  • Page 154 Circuit 131: 15 seconds switch-off delay Setup information Install the two transistors, the diode, the three resistors and the electrolytic capacitor as shown in Fig. 2.131 The six jumper wires come next followed by the jumper, which serves as a switch (shown dashed). For your guidance, we labelled the “switch”...

  • Page 155: Low-Noise High-Impedance Input Amplifier

    2.61 Low-noise high-impedance input amplifier Circuit 132: High-impedance preamplifier Setup information Install the two transistors, the eight resistors, the ceramic capacitor and the electrolytic capacitor as shown in Fig. 2.132 The nine jumper wires come next. Last but not least, connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 156: Nor Gate

    2.62 NOR gate Circuit 133: NOR gate with LED Setup information Install the two transistors, the three diodes and the two resistors as shown in Fig. 2.133. The six four jumper wires come next followed by the jumpers, which serves as a switch (shown dashed). For your guidance we have labelled the switches with high E1 and high E2 Check the placement on the board again and only then connect the battery.
  • Page 157 Circuit 134: NOR gate with moving-coil instrument Setup information Install the two transistors, the two diodes and the two resistors as shown in Fig. 2.134. The four jumper wires come next followed by the jumpers, which serve as switches (shown dashed). For your guidance we have labelled the switches with high E1 and high E2.

  • Page 158: Nand Gate

    The high state of the inputs is caused by closing the respective switch. If the switch is open, the input is low. Such a circuit with the behaviour described above is known in digital electronics as NOR gate. A tablet or notebook PC contains tens of thousands of those gates.
  • Page 159 Input 1 Input 2 Output high dark high high dark high high dark high high illuminated The states high and low at the inputs are achieved by toggling the respective switch. Unlike the previous experiment, the states must be manually wired. In digital electronics such a circuit with the behaviour described above is known as NAND gate.
  • Page 160 Components required: 1 x 2N3904 transis- tor, 2 x 1N4148 silicon diodes, 1 x BAT85 Schottky diode, 1 x 4.7 kΩ resistor, 1 x 10 kΩ resistor, 2 x 22 kΩ resistors, 1 x moving-coil instru- ment, 1 x breadboard, 1 x 9V battery with clip connector Fig.

  • Page 161: Mixing Console

    2.64 Mixing console Circuit 137: Input level mixing console Setup information Install the transistor, the ceramic capacitor and the three resistors as shown in Fig. 2.137. The three jumper wires come next. Check the placement on the board again and only then connect the battery. If you are familiar with the relevant safety guidelines as per VDE and know how to observe them when working with devices that are to be connected to the mains, you can now connect the audio amplifier.
  • Page 162 Circuit 138: output circuit mixing console Setup information Install the two transistors, the two electrolytic capacitors and the five resistors as shown in Fig. 2.138 The seven jumper wires come next. Finally connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 163: Electrometer

    2.65 Electrometer Circuit 139: Electrometer with LED Setup information Install the two transistors, the diode, the ceramic capacitor and two resistors as shown in Fig. 2.139 The six jumper wires come next followed by the jumper, which serves as a switch (shown dashed). For your guid- ance, we labelled the “switch”...
  • Page 164 Circuit 140: Electrometer with moving-coil instrument Setup information Install the two transistors, the ceramic capacitor and two resistors as shown in 2.140. The seven jumper wires come next followed by the jumper, which serves as a switch (shown dashed). For your guidance, we labelled the “switch”...

  • Page 165: Simple Am-Radio

    2.66 Simple AM-Radio Circuit 141: Simple AM-Radio Setup information Install the three transistors, the four resistors, the three ceramic capacitors, the fixed value inductor and the two electrolytic capacitors as shown in Fig. 2.141. Then insert the 20 jumper wires. Last but not least, con- nect the Piezo element.

  • Page 166: Water Alarm

    2.67 Water alarm Circuit 142: Water level alarm with LED Setup information Install the two transistors, the diode and the four resistors as shown in Fig. 2.142. The ten jumper wires come next. Check the placement on the board again and only then connect the battery. Components required: 2 x 2N3904 transistors, 1 x red LED, 1 x 1 kΩ...
  • Page 167 Circuit 143: Water level alarm with moving-coil instrument Setup information Install the two transistors and the four resistors as shown in Fig. 2.143. The ten jumper wires come next. Last but not least connect the moving-coil instrument. Check the placement on the board again and only then connect the battery.

  • Page 168: Telephone Monitor

    2.68 Telephone monitor Circuit 144: Telephone monitor for analogue telephone systems Setup information Install the transistor, the four diodes, the six resistors and the two electrolytic capacitors as shown in Fig. 2.144. The thirteen jumper wires come next. Check the placement on the board again and only then connect the battery.

  • Page 169: Signal Tracker

    2.69 Signal tracker Circuit 145: Simple signal tracker with Piezo element Setup information Install the two transistors, the four resistors and the three electrolytic capacitors as shown in Fig. 2.145. Insert the eight jumpers. Last but not least connect the Piezo element. Check the placement on the board again and only then connect the battery.
  • Page 170 Circuit 146: Simple signal tracker with Piezo element Setup information Install the two transistors, the five resistors and the four electrolytic capacitors as shown in Fig. 2.146 Insert the eight jumpers. Last but not least connect the moving-coil instrument. Check the placement on the board again and only then connect the battery.

  • Page 171: Simple Signal Injector

    2.70 Simple signal injector Circuit 147: Simple signal injector Setup information Install the two transistors, the four resistors and the three electrolytic capacitors as shown in Fig. 2.147. The nine jumper wires come next. Check the placement on the board again and then connect the battery. Components required: 2 x 2N3904 transistors, 2 x 2.2 kΩ...

  • Page 172: Rs232C Monitor

    2.71 RS232C monitor Circuit 148: Simple RS232C monitor Setup information Install the two diodes and the two resistors as shown in Fig. 2.148. The two wire jumpers are next. Check the placement on the board again. Components required: 1 x red LED, 1 x green LED, 1 x 1 kΩ...

  • Page 173: Simple Rc Sine Wave Generator

    Experiment It is still used in systems where PCs are utilized to control machines such as: the serial interface RS-232C of a computer from the days of infancy. If you would like to connect an CNC milling machine or one of the unrivalled practical PSION pocket computers (s3mx or s5mx), our circuit can help to overcome connection issues.
  • Page 174 Experiment If everything is wired correctly, you will hear a clear tone with a sinusoidal waveform coming from your Piezo element once the battery is connected. This is a pure tone without any harmonics unlike the complex tone, which would be composed of several pure tones. This is also the reason why a pure tone sounds arti- ficial and sterile.
  • Page 175 tone which would be a composed of several pure tones. This is also the reason why a pure tone sounds arti- ficial and sterile. In our case, frequency is about 100 Hz. You can use this test signal to check audio circuits. The circuit diagram for this experiment is shown in Chap.

  • Page 176: Oscillating Circuit Tester/Quartz Tester

    2.73 Oscillating circuit tester/Quartz tester Circuit 153: Oscillating circuit tester Setup information Install the two transistors, the two diodes, the three resistors, the fixed value inductor, the five ceramic capacitors and the electrolytic capacitor as shown in Fig. 2.153. The 15 jumpers are next. Check the place- ment on the board again and only then connect the battery.

  • Page 177: Lf Phase Shifter

    2.74 LF phase shifter Circuit 154: LF phase shifter 10° Setup information Install the two transistors, the six resistors and the three electrolytic capacitors as shown in Fig. 2.154. The nine jumper wires come next. Check the placement on the board again and only then connect the battery. Components required: 1 x 2N3904 transis- tor, 1 x 10 kΩ...
  • Page 178 Circuit 155: LF phase shifter 90° Setup information Install the transistor, the six resistors and the three electrolytic capacitors as shown in Fig. 2.155. The nine jumper wires come next. Check the placement on the board again and only then connect the battery. Components required: 1 x 2N3904 transistor, 1 x 100 Ω...
  • Page 179 Circuit 156: LF phase shifter 180° Setup information Install the transistor, the six resistors and the three electrolytic capacitors as shown in Fig. 2.156. The nine jumper wires come next. Check the placement on the board again and only then connect the battery. Components required: 1 x 2N3904 transistor, 3 x 2.2 kΩ...

  • Page 180: Headphone Amplifier

    2.75 Headphone amplifier Circuit 157: Headphone amplifier with Piezo element Setup information Install the two transistors, the six resistors and the four electrolytic capacitors as shown in Fig. 2.157. The twelve jumper wires come next. Last but not least connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 181: Needle Pulse Generator

    2.76 Needle pulse generator Circuit 158: Needle pulse generator 60 Hz Setup information Install the two transistors, the two resistors and the ceramic capacitor as shown in Fig. 2.158. The nine jumper wires come next. Last but not least connect the Piezo element. Check the placement on the board again and only then connect the battery.
  • Page 182 Circuit 159: Needle pulse generator 150 Hz Setup information Install the two transistors, the two resistors and the ceramic capacitor as shown in Fig. 2.159. The nine jumper wires come next. Last but not least connect the Piezo element. Check the placement on the board again and only then connect the battery.
  • Page 183 Circuit 160: Needle pulse generator 500 Hz Setup information Install the two transistors, the two resistors and the two ceramic capacitors as shown in Fig. 2.160 The nine jumper wires come next. Last but not least connect the Piezo element. Check the placement on the board again and only then connect the battery.
  • Page 184 Circuit 161: Needle pulse generator 2 kHz Setup information Install the two transistors, the two resistors and the ceramic capacitor as shown in Fig. 2.161. The nine jumper wires come next. Last but not least connect the Piezo element. Check the placement on the board again and only then connect the battery.
  • Page 185 Circuit 162: Needle pulse generator 4 kHz Setup information Install the two transistors, the two resistors and the ceramic capacitor as shown in Fig. 2.162. The nine jumper wires come next. Last but not least connect the Piezo element. Check the placement on the board again and only then connect the battery.
  • Page 186 Circuit 163: Needle pulse generator 5 kHz Setup information Install the two transistors, the two resistors and the two ceramic capacitors as shown in Fig. 2.163 The ten jumper wires come next. Last but not least connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 187: Jimi Hendrix Sound Generator

    2.77 Jimi Hendrix sound generator Circuit 164: Jimi Hendrix sound generator Setup information Install the two transistors, the diode, the five resistors and the three electrolytic capacitors as shown in Fig. 2.194.The eleven jumper wires come next. Last but not least connect the Piezo element. Check the placement on the board again and only then connect the battery.
  • Page 188 Circuit 165: Guitar Distortion Setup information Install the two transistors, the diode, the five resistors and the three electrolytic capacitors as shown in Fig. 2.165. The eleven jumper wires come next. Last but not least connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 189: Lie Detector

    2.78 Lie detector Circuit 166: FET lie detector with LED indicator Setup information Install the transistor, the LED diode and the three resistors as shown in Fig. 2.166. The six jumper wires come next. Two bare wire ends serve as skin sensor. Check the placement on the board and only then con- nect the battery.
  • Page 190 Circuit 167: FET lie detector with moving-coil instrument Setup information Install the transistor, the LED diode and the three resistors as shown in Fig. 2.166. The five jumper wires come next. Two bare wire ends serve as skin sensor. Check the placement on the board and only then con- nect the battery.
  • Page 191 Circuit 168: FET lie detector with LED indicator Setup information Install the two transistors, the diode and the three resistors as shown in Fig. 2.168 followed by the eight jumper wires. Two bare wire ends serve as skin sensor. Check the placement on the board again and only then connect the battery.
  • Page 192 Circuit 169: Lie detector with moving-coil instrument Setup information Install the two transistors and the three resistors as shown in Fig. 2.169 followed by the seven jumper wires. Two bare wire ends serve as skin sensor. Check the placement on the board again and only then connect the battery.

  • Page 193: Buffer Amplifier

    2.79 Buffer amplifier Circuit 170: Buffer amplifier for magnetic loop antenna Setup information Install the transistor, the two resistors and the two ceramic capacitors as shown in Fig. 2.170. The three jumper wires come next. Check the placement on the board again and only then connect the battery. Components required: 1 x J111 FET transistor, 1 x 1 kΩ...
  • Page 194 Circuit 171: Buffer amplifier for condenser microphone Setup information Install the transistor, the two resistors and the two ceramic capacitors as shown in Fig. 2.171. The three jumper wires come next. Check the placement on the board again and only then connect the battery. Components required: 1 x J111 FET transistor, 1 x 2.2 kΩ...

  • Page 195: Hf Generator

    2.80 HF generator Circuit 172: Simple HF generator without inductor Setup information Install the two transistors, the four resistors and the three electrolytic capacitors as shown in Fig. 2.172. The twelve jumper wires come next. Check the placement on the board again the battery. Components required: 2 x 2N3904 transistors, 2 x 10 kΩ...

  • Page 196: Af Switch

    2.81 AF switch Circuit 173: Electronic AF switch Setup information Install the transistor, the diode, the five resistors and the two electrolytic capacitors as shown in Fig. 2.173. The seven jumper wires come next. One jumper wire end is inserted and serves as the “switch”. For your guidance, it is shown dashed and labelled with dampening on.

  • Page 197: Voltage Regulator

    2.82 Voltage regulator Circuit 174: Stabilizer for 1.4 V Setup information Install the transistor, the four resistors and the electrolytic capacitor as shown in Fig. 2.174. The six jumper wires come next. Check the placement on the board again and only then connect the battery. Components required: 1 x 2N3904 transistor, 1 x 100 Ω...
  • Page 198 Circuit 175: Stabilizer for 2 V Setup information Install the transistor, the three resistors and the electrolytic capacitor as shown in Fig. 2.175. The seven jumper wires come next. Check the placement on the board again and only then connect the battery. Components required: 1 x 2N3904 transistor, 1 x 470 Ω...
  • Page 199 Circuit 176: Stabilizer for 3.6 V Setup information Install the transistor, the three resistors and the electrolytic capacitor as shown in Fig. 2.176. The seven jumper wires come next. Check the placement on the board again and only then connect the battery. Components required: 1 x 2N3904 transistor, 3 x 1 kΩ...
  • Page 200 Circuit 177: Stabilizer for 4.4 V Setup information Install the transistor, the four resistors and the electrolytic capacitor as shown in Fig. 2.177. The six jumper wires come next. Check the placement on the board again and only then connect the battery. Components required: 1 x 2N3904 transistor, 1 x 470 Ω...
  • Page 201 Circuit 178: Stabilizer for 5.2 V Setup information Install the transistor, the three resistors and the electrolytic capacitor as shown in Fig. 2.178. The seven jumper wires come next. Check the placement on the board again and only then connect the battery. Components required: 1 x 2N3904 transistor, 2 x 1 kΩ...

  • Page 202: Lc Generator

    2.83 LC generator Circuit 179: HF generator 150 kHz Setup information Install the transistor, the four resistors, the four ceramic capacitors and the fixed value inductor as shown in Fig. 2.179 followed by the eight jumpers. Check the placement on the board again and only then connect the battery.
  • Page 203 Circuit 180: HF generator 420 kHz Setup information Install the transistor, the four resistors, the four ceramic capacitors and the fixed value inductor as shown in Fig. 2.180 followed by the eight jumpers. Check the placement on the board again and only then connect the battery.

  • Page 204: Simple Battery Monitor

    2.84 Simple battery monitor Circuit 181: Simple 7.5V battery monitor Setup information Install the two transistors, the diode and the four resistors as shown in Fig. 2.181 followed by the ten jumper wires. Check the placement on the board again and only then connect the battery. Components required: 2 x 2N3904 transistors, 1 x red LED, 1 x 2.2 kΩ...
  • Page 205 Circuit 182: Simple 8.2V battery monitor Setup information Install the two transistors, the diode and the five resistors as shown in Fig. 2.182 followed by the 13 jumper wires. Check the placement on the board again and only then connect the battery. Components required: 2 x 2N3904 transistors, 1 x red LED, 2 x 2.2 kΩ...

  • Page 206: Audio Fade-In And Fade-Out

    2.85 Audio Fade-in and Fade-out Circuit 183: Audio Fade-in and Fade-out Setup information Install the transistor, the diode, the five resistors and the three electrolytic capacitors as shown in Fig. 2.183 Insert the eight jumpers. A jumper wire with only one end inserted serves as the “switch”. For your guid- ance it is shown dashed and labelled with Fade in/Fade out.

  • Page 207: Level Meter

    2.86 Level meter Circuit 184: Peak level display with LED Setup information Install the transistor, the two diodes and the two resistors as shown in Fig. 2.184 followed by the jumper wire. Check the placement on the board again and only then connect the battery. If you are familiar with the relevant safety guidelines as per VDE and know how to observe them when working with devices that are to be connected to the mains, you can now connect the audio amplifier.
  • Page 208 Circuit 185: Peak level display with LED Setup information Install the transistor, the diode and the four resistors as shown in Fig. 2.185 followed by the jumper wire. Check the placement on the board again and only then connect the battery. If you are familiar with the relevant safety guidelines as per VDE and know how to observe them when working with devices that are to be connected to the mains, you can now connect the audio amplifier.

  • Page 209: Acoustic Continuity Tester

    2.87 Acoustic continuity tester Circuit 186: Acoustic continuity tester Setup information Install the two transistors, the four resistors and the two ceramic capacitors as shown in Fig. 2.186 followed by the eight jumper wires. Finally connect the Piezo element connect the Piezo element. Check the place- ment on the board again and only then connect the battery.

  • Page 210: Logic Probe

    2.88 Logic probe Circuit 187: Active TTL CMOS probe with LED display Setup information Install the two transistors, the four diodes and the four resistors as shown in Fig. 2.187 The seven jumper wires come next. Check the placement on the board again and only then connect the battery. Components required: 2 x 2N3904 transis- tors, 2 x 1N4148 silicon...
  • Page 211 Circuit 188: Active TTL CMOS probe with LED display Setup information Install the two transistors, the four diodes and the five resistors as shown in Fig. 2.188. The seven jumper wires come next. Last but not least connect the moving-coil instrument. Check the placement on the board again and only then connect the battery.

  • Page 212: Active Probe

    2.89 Active probe Circuit 189: Simple active probe with Piezo element Setup information Install the transistor, the three resistors, the ceramic capacitor and the three electrolytic capacitors Fig. 2.189 followed by six jumper wires. Last but not least connect the Piezo element. Check the placement on the board again and only then connect the battery.
  • Page 213 Circuit 190: Simple active probe with moving-coil instrument Setup information Install the transistor, the diode, the five resistors, the ceramic capacitor and the two electrolytic capacitors as shown in Fig. 2.190 The seven jumper wires come next. Last but not least connect the moving-coil instru- ment.
  • Page 214 Circuit 191: Simple active probe with Piezo element Setup information Install the two transistors, the two diodes, the four resistors, the ceramic capacitor and the electrolytic capacitor as shown in Fig. 2.191. The thirteen jumper wires come next. Finally connect the Piezo element. Check the placement on the board again and only then connect the battery.
  • Page 215 Circuit 192: Simple active probe with moving-coil instrument Setup information Install the two transistors, the three diodes, the six resistors, the ceramic capacitor and the two electrolytic capacitors as shown in Fig. 2.192 The seventeen jumper wires come next. Last but not least, connect the moving-coil instrument.

  • Page 216: Ir Control

    2.90 IR control Circuit 193: Simple IR transmitter Setup information Install the diode, the resistor and the electrolytic capacitor as shown in Fig. 2.193 followed by the jumper wire. Check the placement on the board again and only then connect the battery. Components required: 1 x IR diode, 1 x 4.7 kΩ...
  • Page 217 Circuit 194: Simple IR receiver Setup information Install the transistor, the resistor and the electrolytic capacitor as shown in Fig. 2.194 followed by the jumper wire. Finally connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 218: Constant Voltage Source

    2.91 Constant voltage source Circuit 195: constant voltage source Setup information Install the transistor, the diode and the two resistors as shown in Fig. 2.195 followed by the four jumper wires. Check the placement on the board again and only then connect the battery. Components required: 1 x 2N3904 transistor, 1 x red LED, 1 x 2.2 kΩ...
  • Page 219 Circuit 196: constant voltage source Setup information Install the transistor, the diode and the three resistors as shown in Fig. 2.196. The four jumper wires come next. Last but not least connect the moving-coil instrument. Check the placement on the board again and only then connect the battery.

  • Page 220: Class A End-Level

    2.92 Class A end-level Circuit 197: Class A amplifier with Piezo element Setup information Install the transistor, the four resistors and the two electrolytic capacitors as shown in Fig. 2.197 followed by the four jumper wires. Last but not least connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 221: Ir Control

    2.93 IR control Circuit 198: Infrared transmitter Setup information Install the diode and the resistor as shown in Fig. 2.198 followed by the jumper wire. Check the placement on the board again and only then connect the battery. Components required: 1 x IR diode, 1 x 1 kΩ...
  • Page 222 Circuit 199: Infrared receiver Setup information Install the transistor, the diode and the resistor as shown in Fig. 2.199 followed by the four jumper wires. Check the placement on the board again and only then connect the battery. Components required: 1 x PT331C phototransis- tor, 1 x red LED, 1 x 1 kΩ...

  • Page 223: Push-Pull Amplifier

    2.94 Push-Pull amplifier Circuit 200: Iron-free push-pull amplifier Setup information Install the three transistors, the two diodes, the three resistors and the two electrolytic capacitors as shown in Fig. 2.200 followed by the ten jumper wires. Last but not least, connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 224: Switch-Off Delay

    2.95 Switch-off delay Circuit 201: 1 second switch-on delay Setup information Install the transistor, the diode, the four resistors and the electrolytic capacitor as shown in fol- Fig. 2.201 lowed by the four jumper wires and the jumper, which serve as switch (shown dashed). For your guidance, we labelled the “switch”...
  • Page 225 Circuit 202: 3 seconds switch-off delay Setup information Install the transistor, the diode, the four resistors and the electrolytic capacitor as shown in Fig. 2.202 fol- lowed by the four jumper wires and the jumper, which serve as switch (shown dashed). For your guidance, we labelled the “switch”...
  • Page 226 Circuit 203: 7 seconds switch-off delay Setup information Install the transistor, the diode, the four resistors and the electrolytic capacitor as shown in Fig. 2.203 fol- lowed by the three jumper wires and the jumper, which serve as switch (shown dashed). For your guidance, we labelled the “switch”...

  • Page 227: Siren

    2.96 Siren Circuit 204: Piercing siren sound with Piezo element Setup information Install the two transistors, the five resistors and the two ceramic capacitors as shown in Fig. 2.204. The fifteen jumper wires come next. Finally connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 228: Discrete Opamp

    2.97 Discrete OPAMP Circuit 205: Discrete Operational amplifier Setup information Install the three transistors and the two resistors as shown in Fig. 2.205 followed by ten jumper wires. Check the placement on the board again and only then connect the battery. Components required: 2 x 2N3904 transistors, 1 x 2N3906 transistor,...
  • Page 229 Circuit 206: Discrete Operational amplifier with Piezo element Setup information Install the three transistors, the four resistors and the two electrolytic capacitors as shown in Fig. 2.206 The fifteen jumper wires come next. Last but not least connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 230: Nand And Nor Gates

    2.98 NAND and NOR gates Circuit 207: NOR gate with LED Setup information Install the two transistors, the three diodes and the four resistors as shown in Fig. 2.207. The eighteen jumper wires come next followed by the jumpers, which serve as switches (shown dashed). For your guid- ance, we have labelled the switches with high E1, low E1 and high E2, low E2.
  • Page 231 The high state of the inputs is caused by closing the respective switch at the high position. In digital elec- tronics such a circuit with the behaviour described above is known as NOR gate. A tablet or notebook PC contains tens of thousands of those gates. The circuit diagram for this experiment is shown in Chap.

  • Page 232: Active Zener Diode

    Input 1 Input 2 Output high dark high high dark high high dark high high illuminated The states high and low at the inputs are achieved by toggling the respective switch. In digital electronics such a circuit with the behaviour described above is known as NAND gate. A tablet or notebook PC con- tains tens of thousands of those gates.
  • Page 233 Experiment This circuit delivers constant voltage at the output, even if battery voltage is fluctuating. It behaves just like a properly wired Zener diode. In our case, we have an output voltage of 4 V. The battery voltage may fluctu- ate between 7V and 9V.
  • Page 234 Circuit 211: Discreet 7.4V Zener diode Setup information Install the two transistors and the five resistors as shown in Fig. 2.211. The eleven jumper wires come next. Check the placement on the board again and only then connect the battery. Components required: 1 x 2N3904 transistor, 1 x 2N3906 transistor,...

  • Page 235: Detector Receiver

    2.100 Detector receiver Circuit 212: Simple detector receiver Setup information Install the diode and the ceramic capacitor as shown in Fig. 2.212 followed by the jumper wire. Last but not least connect the Piezo element. Check the placement on the board again. You can significantly increase the sensitivity of the Piezo element by using a sound plate or even a sound box.
  • Page 236 Circuit 213: Improved detector receiver Setup information Install the diode, the fixed value inductor and the two electrolytic capacitors as shown in Fig. 2.213 fol- lowed by the four jumper wires. Last but not least connect the Piezo element. Check the placement on the board again.
  • Page 237 Circuit 214: Detector receiver with amplifier Setup information Install the transistor, the diode, the two resistors, the fixed value inductor and the two ceramic capacitors as shown in Fig. 2.214. The nine jumper wires come next. Last but not least connect the Piezo element. Check the placement on the board again and only then connect the battery.

  • Page 238: Simple Condenser Tester (Tantal, E-Caps)

    2.101 Simple condenser tester (Tantal, E-caps) Circuit 215: Capacitor test with LED indicator Setup information Install the diode and the resistor as shown in Fig. 2.215 The two jumper wires come next. The electrolytic capacitor to be tested is installed at the location shown. Check the placement on the board again and only then connect the battery.

  • Page 239: Generating Hydrogen

    Components required: 1 x 2.2 kΩ resistor, 1 x moving-coil instrument, 1 x breadboard, 1 x 9V bat- tery with clip connector Fig. 2.216: Capacitor test with moving-coil instrument Experiment Use this circuit to easily check whether an electrolytic capacitor in the range of 1 uF to 100 μF is working properly.
  • Page 240 Components required: 1 x 220 Ω resistor, 1 x moving- coil instrument, 1 x breadboard, 1 x 9V battery with clip con- nector Fig. 2.217: Generating hydrogen Experiment It is said that hydrogen promises future human mobility. A fuel cell transforms hydrogen and oxygen envi- ronmentally neutral in water and generates electricity during this process.
  • Page 241 Circuit 218: Generating hydrogen in an environmental friendly way Setup information Install the resistor and the jumper as shown in Fig. 2.218. Then install the moving-coil instrument and the solar cell. We are using two wires with bare ends as electrodes, which we dip in a glass filled with water. Check the placement on the board again and only then expose the solar cell to strong light.
  • Page 242 Experiment It is said that hydrogen promises future human mobility. A fuel cell transforms hydrogen and oxygen envi- ronmentally neutral in water and generates electricity during this process. It is used to drive electro vehicles. The common method used to mass produce hydrogen is via the electrolysis of water, that is the separation of water molecules into the two components hydrogen and oxygen by means of electrical energy.

  • Page 243: Circuit Diagrams

    3 Circuit diagrams This chapter contains all the circuit diagrams for the circuit used in our experiments. You will not necessar- ily need them to reproduce the experiments. But why not make the next step and get into the fascinating world of electronics where you build and learn about electronic circuits and understand how to realize your own circuit ideas.
  • Page 244 Circuit 1 to 6: A large series resistor is required for voltage measurements; a small parallel resistor for cur- rent measurements. Fig. 3.6: Circuit 6: Current measurement Fig. 3.7: Circuit 7: Determining the connection sequence of a PNP transistor with a greater shunt resistance Fig.
  • Page 245 Fig. 3.10: Circuit 10: NPN transistor B test Fig. 3.11: Circuit 11: Threshold voltage silicon diode Fig. 3.12: Circuit 12: Threshold voltage Schottky diode Fig. 3.13: Circuit 13: Threshold voltage red LED Fig. 3.14: Circuit 14: Threshold voltage green LED Circuit 11 –...
  • Page 246 Fig. 3.15: Circuit 15: Threshold voltage yellow LED Fig. 3.16: Circuit 16: Threshold voltage infrared diode Fig. 3.17: Circuit 17: Awesome double turn signal Function of the Circuits 17 and 18: The two transistors T1 and T2 are switching each other on or off with a time delay.
  • Page 247 Fig. 3.18: Circuit 18: Boring double turn signals Fig. 3.19: Circuit 19: Electronic brain cell Circuits 19 and 20: A strong base current flows through T2, if a button is activated. The LED turns on when the connection is made. At that moment, R4 blocks transistor T1. Upon releasing the button, a small amount of holding current flows through R3 and on to the base of T2 keeping it electrically conductive.
  • Page 248 Fig. 3.20: Circuit 20: A bell with a memory Fig. 3.21: Circuit 21: Flashing tail light Circuits 21 and 22: The functioning principle is described on page 248.
  • Page 249 Fig. 3.22: Circuit 22: Flashing bicycle light Fig. 3.23: Circuit 23: Simple solar light Fig. 3.24: Circuit 24: Solar light with battery...
  • Page 250 Fig. 3.25: Circuit 25: Automatic solar light with battery Fig. 3.26: Circuit 26: 2 seconds switch-off delay Circuit 26 – 28: Electrolytic capacitor C1 charges fully, when button S1 is activated. R2 and R3 are used to discharge the e-cap. For as long as the capacitor voltage remains above the threshold voltage of the transis- tors, T1 and T2 remain switched through and LED1 is lit.
  • Page 251 Fig. 3.27: Circuit 27: 4 seconds switch-off delay Fig. 3.28: Circuit 28: 20 seconds switch-off delay...
  • Page 252 Fig. 3.29: Circuit 29: Simple bicycle light Fig. 3.30: Circuit 30: Automatic bicycle light with solar cell Circuit 30: T1 blocks, if the solar cell is not supplying power due to darkness. R2 triggers T2 to switch through and LED1 turns on. However, T1 becomes conductive in a bright environment and the solar cell sup- plies electricity.
  • Page 253 Fig. 3.31: Circuit 31: Automatic bicycle light with phototransistor Fig. 3.32: Circuit 32: Simple peak VU meter with Circuit 31: When it is dark, the phototransistor PT1 blocks, R1 is switched via T1, LED1 turns on. Bright ambi- ent light turns the phototransistor on, T1 blocks, LED1 turns off.
  • Page 254 Fig. 3.33: Circuit 33: Peak VU meter with coil- moving instrument Fig. 3.34: Circuit 34: LM antenna amplifier for antennas with longer wires Circuits 32 and 33: The audio signal is rectified by D1 and delivered to the base of T1. If the threshold is exceeded, T1 is electrically conductive, LED1 goes on or M1 shows deflection.
  • Page 255 Fig. 3.35: Circuit 35: LM antenna amplifier for short wire antennas Fig. 3.36: Circuit 36: Handy continuity tester Fig. 3.37: Circuit 37: Diode tester...
  • Page 256 Fig. 3.38: Circuit 38:High pass from on 650 Hz Fig. 3.39: Circuit 39: High pass from on 2.5 kHz Circuit 38 – 40: AC resistance of a capacitor behaves inversely proportional to frequency. If the frequency increases, the AC resistance drops. By means of different capacity values, different cut-off frequencies of high-pass circuits can be realized.
  • Page 257 Fig. 3.40: Circuit 40: High pass from on 5.5 kHz Fig. 3.41: Circuit 40: Electronic level control with large control range Circuit 41: FET transistor T1 functions as T2 emitter resistor. The operating point of T1 defines therefore the gain of T2. The operating point of T1 and thus the gain of T2 is set by the control voltage.
  • Page 258 Fig. 3.42: Circuit 42: Active 8.5V battery monitor Fig. 3.43: Circuit 43: Active 7.8V battery monitor...
  • Page 259 Fig. 3.44: Circuit 44: Two-stage AF pream- plifier Fig. 3.45: Circuit 45: Meters for 4.7 V Zener diodes and higher Circuits 45 and 46: The two transistors ensure that current of 5 mA flows through the Zener diode Z, regard- less of the voltage value of the Zener diode.
  • Page 260 Fig. 3.46: Circuit 46: Meters for 1.5 V Zener diodes and higher Fig. 3.47: Circuit 47: Discreet 2.2V Zener diode...
  • Page 261 Fig. 3.48: Circuit 48: Discreet 2.9V Zener diode Fig. 3.49: Circuit 49: Discreet 3.7V Zener diode...
  • Page 262 Fig. 3.50: Circuit 50: Discreet 4.4V Zener diode Fig. 3.51: Circuit 51: Relax- ing pendulum clock Circuits 51 and 52: The collector of T1 delivers a feedback to the base of T1 via C1. If T1 is conductive, also T2 is switched through.
  • Page 263 Fig. 3.52: Circuit 52: Stimu- lating mantel clock Fig. 3.53: Circuit 53: Light sensitive switch with green LED Circuit 53: No current flows through LED1 while it is dark. T1 and T2 are blocked. LED2 remains dark. As soon as light falls on LED1, current flows and T1 and T2 are conductive. LED2 is lit.
  • Page 264 Fig. 3.54: Circuit 54: Light sensitive switch with solar cell Fig. 3.55: Circuit 55: Light sensitive switch phototran- sistor Circuit 54: The solar cell delivers no current while it is dark, T1 and T2 are blocked. LED1 remains dark. The solar cell converts light into electricity, which in return puts T1 and T2 in the conductive state and LED1 turns Circuit 55: The functioning principle is described on page 265.
  • Page 265 Fig. 3.56: Cir- cuit 56: Audio limiter Fig. 3.57: Circuit 57: Amplifier for a storm detector...
  • Page 266 Fig. 3.58: Circuit 58: DC-DC con- verter 9V to 18V with coil-moving instrument Fig. 3.59: Circuit 59: DC-DC converter 9V to 35V with coil- moving instrument Circuit 58 – 62: T1 and T2 are wired to work as a pulse generator. Thus, L1 connects and disconnects to the battery via T2 again and again.
  • Page 267 Fig. 3.60: Circuit 60: DC-DC converter 9V to 35V with coil- moving instrument Fig. 3.61: Circuit 61: DC-DC converter 9V to 55V with LED...
  • Page 268 Fig. 3.62: Circuit 62: DC-DC converter 9V to 75V Fig. 3.63: Circuit 63 – Stabilizer for 1.0 V Circuit 63 – 65: If the output voltage drops, T2 receives less control voltage, thus becomes less conductive. This increases the control current of T1 and consequently T3. The higher current flow through T3 increases the output voltage to the extent that the old value is restored.
  • Page 269 Fig. 3.64: Circuit 64 – Stabilizer for 1.9 V Fig. 3.65: Circuit 65 – Stabilizer for 2.5 V...
  • Page 270 Fig. 3.66: Circuit 66 – Schmitt trig- ger circuit with 4V hysteresis Fig. 3.67: Circuit 67 – Schmitt trig- ger circuit with 2V hysteresis Circuits 66 and 67: The different values of R2 and R4 achieve different levels of voltage drops via R3 in the states On or Off.
  • Page 271 Fig. 3.68: Circuit 68: LED blinker 1 Hz Fig. 3.69: Circuit 69: LED blinker 3 Hz Circuits 68 and 69: the output is fed back to the base of T1 via R1. R2 and C2 ensure the time delay. If T2 is electrically conductive, the feedback ensures that T1 also switches through.
  • Page 272 Fig. 3.70: Circuit 70 – Riaa equal- izer Fig. 3.71: Circuit 71: low-noise preamplifier Fig. 3.72: Circuit 72 – RC low pass 1.5 kHz...
  • Page 273 Fig. 3.73: Circuit 73 – RC low pass 3 kHz Fig. 3.74: Circuit 74 – RC low pass 3.4 kHz Fig. 3.75: Circuit 75 – RC high pass 160 Hz Fig. 3.76: Circuit 76 – RC high pass from on 1.6 kHz Fig.
  • Page 274 Fig. 3.78: Circuit 78 – Quiztimer 3 seconds Fig. 3.79: Circuit 79 – Quiztimer 8 seconds Circuit 78 – 80: Button S1 is used to fully charge the electrolytic capacitor C1/C2. At R2 discharge occurs. For as long as the capacitor voltage exceeds the threshold voltage of T1 plus T2, T2 remains connected, LED1 is lit.
  • Page 275 Fig. 3.80: Circuit 80 – Quiztimer 30 seconds Fig. 3.81: Circuit 81: Handy diode tester...
  • Page 276 Fig. 3.82: Circuit 82: Handy diode tester with moving- coil instrument Fig. 3.83: Circuit 83: Electrolytic capacitor lets Fig. 3.84: Circuit 84: Electrolytic capacitor blocks direct current direct current pass through Fig. 3.85: Circuit 85: Fog horn...
  • Page 277 Fig. 3.86: Circuit 86: Mosquito repeller Fig. 3.87: Circuit 87 – Metronome with discreet unijunction transistor Circuit 86: The functioning principle is described on page 248. Circuit 87: If the voltage at the emitter of T2 reaches ignition level, the unijunction transistor switches abruptly through.
  • Page 278 Fig. 3.88: Circuit 88 – Constant current power Fig. 3.89: Circuit 89 – Constant current power source with FET source with FET transistor transistor Fig. 3.90: Circuit 90 – Constant current power Fig. 3.91: Circuit 91 – Constant current power source with bipolar source with bipolar transistor transistor...
  • Page 279 Fig. 3.92: Circuit 92 – LED fireworks Fig. 3.93: Circuit 93: Fast LED flash Circuit 92: The functioning principle is described on page 248. Circuits 93 and 94: The time-delayed feedback from the output (collector T2) to the input (base T1) to elec- trolytic capacitor C2 ensures that T2 briefly turns on at regular intervals.
  • Page 280 Fig. 3.94: Circuit 94: Slow LED flash Fig. 3.95: Circuit 95: Fog horn Circuit 95: The functioning principle is described on page 248.
  • Page 281 Fig. 3.96: Circuit 96 – Two LED in Waltz time Fig. 3.97: Circuit 97 – A needle fidgets in waltz time Circuits 96 and 97: The functioning principle is described on page 248.
  • Page 282 Fig. 3.98: Circuit 98 – Constant current power supply for LEDs Fig. 3.99: Circuit 99 – Constant current power supply for LEDs Fig. 3.100: Circuit 100: Electronic level control Circuits 98 and 99: The flat output characteristics of the emitter-to-ground circuit ensure that diode current will not depend on the type of an LED.
  • Page 283 Fig. 3.101: Circuit 101 – Charge circuit for AA batteries Fig. 3.102: Circuit 102 – Charge circuit for AA batteries Fig. 3.103: Circuit 103 – Discharge circuit for AA batteries...
  • Page 284 Fig. 3.104: Circuit 104 – Discharge circuit for AA batteries Fig. 3.105: Circuit 105 – Whistle buoy Circuit 105 and 106: Capacitor C1 ensures the time delayed feedback from the output (T1 emitter) to the input (base T2). The two transistors switch each other on in cycles. The process starts with S1.
  • Page 285 Fig. 3.106: Circuit 106 – Whistle buoy Fig. 3.107: Circuit 107 – Constant current source 1.2 mA Fig. 3.108: Circuit 108 – Constant current source 2 mA Circuit 107 to 109 The flat output characteristics of the emitter-to-ground circuit ensure that the current flow- ing through R3 (or R4 or R5) is independent of this resistor value (within certain limits).
  • Page 286 Fig. 3.109: Circuit 109 – Constant current source 5.7 mA Fig. 3.110: Circuit 110 – Hawaiian guitar Circuit 110: Capacitor C1 ensures the time delayed feedback from the circuit output (collector T2) to the input (base T1). The extend of the time delay defines the pitch and is set with R1. By means of the feedback, the two transistors are periodically switched on and off.
  • Page 287 Fig. 3.111: Circuit 111 – Glass breakage detector Fig. 3.112: Circuit 112 – Glass breakage detector Fig. 3.113: Circuit 113 – Trill gen- erator...
  • Page 288 Fig. 3.114: Circuit 114 – Iron-free push-pull output stage for Piezo horns Fig. 3.115: Circuit 115 – Flicker- ing light Circuit 114: In a push-pull amplifier, the two power amp transistors are sharing the job. T2 takes over all half waves with the higher voltage, T3 manages the half waves with the lower voltage during an inactive state, current flowing through T2 and T3 is very small.
  • Page 289 Fig. 3.116: Circuit 116 – On button with sensor Fig. 3.117: Circuit 117 – Off button with sensor Circuit 116 and 117: The FET transistor (T1 in the circuit) has a very high input resistance. Thus the very low conductivity of human skin is enough to turn on the transistor when the sensor surfaces are touched with a finger.
  • Page 290 Fig. 3.118: Circuit 118 – HF watch- dog with LED indicator Fig. 3.119: Circuit 119 – HF watchdog with moving-coil instrument...
  • Page 291 Fig. 3.120: Circuit 120: Electronic level control Fig. 3.121: Cir- cuit 121: Sensor toggle switch with LED Circuit 120: FET transistor T1 acts as a variable resistor and forms a voltage divider together with R2. The ratio and thus the degree of damping is adjusted by means of the control voltage. Circuit 121 and 122: Activating Tab on turns on T2 and T3.
  • Page 292 Fig. 3.122: Cir- cuit 122: Sensor toggle switch with moving-coil instrument Fig. 3.123: Circuit 123: Voltage doubler with moving-coil instrument Circuit 123 and 124: Each half-wave charges C1 or C2 depending on its sign. With the next charge, the voltage of C1 plus the rectified half-wave is fed to C2.
  • Page 293 Fig. 3.124: Circuit 124: Volt- age doubler with moving-coil instrument Fig. 3.125: Circuit 125 – Solar charger for AA battery Fig. 3.126: Circuit 126 – Solar charger for two AA batteries Fig. 3.127: Circuit 127: Electronic drum...
  • Page 294 Fig. 3.128: Circuit 128 – Switch on delay 0.5 seconds Fig. 3.129: Circuit 129 – 2 seconds switch-on delay Circuit 128 to 131 The electrolytic capacitor C1 is charged via R1. Depending on the values used this process can vary in length. Once the threshold voltage of T1 plus T2 is exceeded, the transistors turn on, LED1 is lit.
  • Page 295 Fig. 3.130: Circuit 130 – 4 seconds switch-on delay Fig. 3.131: Circuit 131 – 15 seconds switch- off delay...
  • Page 296 Fig. 3.132: Circuit 132: High-impedance pre- amplifier Fig. 3.133: Circuit 133 – NOR gate with Circuit 133 and 134: The output is turned on, if either T1 or T2 and if both transistors are turned on. That is the typical behaviour of a NOR gate.
  • Page 297 Fig. 3.134: Circuit 134 – NOR gate with moving-coil instru- ment Fig. 3.135: Circuit 135 – NAND gate with LED Circuit 135 and 136: The output turns on, if input 1 and input 2 are both turned to high. In all other cases the output is not switched through.
  • Page 298 Fig. 3.136: Circuit 136 – NAND gate with moving- coil instrument Fig. 3.137: Circuit 137: Input level Mixing console...
  • Page 299 Fig. 3.138: Circuit 138: output level Mixing console Fig. 3.139: Circuit 139 – Electrometer with Circuit 139 and 140: The two transistors configured as Darlington pair feature a very high input resistance. This creates a high voltage drop even at very small input current, this in return switches the transistors through and LED1 is turned on.
  • Page 300 Fig. 3.140: Circuit 140 – Electrometer with moving-coil instrument Fig. 3.141: Circuit 141: Simple AM-Radio...
  • Page 301 Fig. 3.142: Circuit 142 – Water level alarm with LED Fig. 3.143: Circuit 143 – Water level alarm with moving-coil instrument Circuit 142 and 143: The functioning principle is described on page 301.
  • Page 302 Fig. 3.144: Circuit 144 – Telephone monitor for analogue telephone systems Fig. 3.145: Circuit 145 – Simple signal tracker with Piezo element...
  • Page 303 Fig. 3.146: Circuit 146 – Simple signal tracker with moving-coil instrument Fig. 3.147: Circuit 147: Simple signal injector Fig. 3.148: Circuit 148: Simple RS-232C monitor...
  • Page 304 Fig. 3.149: Circuit 149 – Pin assignment of the RS-232C interface Fig. 3.150: Circuit 150: Simple 1kHz tone generator Fig. 3.151: Circuit 151: Simple 100Hz tone generator Circuit 150 to 152 An RC phase shifter chain (C1 to C3, R4 and R5) forms a time-delayed feedback from the collector to the base.
  • Page 305 Fig. 3.152: Circuit 152 – Simple tone genera- tor 10 kHz Fig. 3.153: Circuit 153: Oscillating circuit tester Fig. 3.154: Circuit 154 – NF phase shifter 10°...
  • Page 306 Fig. 3.155: Circuit 155 – NF phase shifter 90° Fig. 3.156: Circuit 156: LF phase shifter 180° Circuit 154 to 156: The electrolytic capacitor C2 and R5 together form a phase shifter. A phase-shifted signal is thus shifted from the output (collector T1) to the input (emitter T1). There the original signal is mixed in, creating the typical phaser sound effect.
  • Page 307 Fig. 3.157: Circuit 157 – Headphone amplifier with Piezo element Fig. 3.158: Circuit 158 – Needle pulse generator 60 Hz Fig. 3.159: Circuit 159 – Needle pulse generator 150 Hz...
  • Page 308 Fig. 3.160: Circuit 160 – Needle pulse generator 500 Hz Fig. 3.161: Circuit 161 – Needle pulse generator 2 kHz Circuit 157 to 163: T1 and T2 form a sensitive bistable amplifier. A feedback is triggered with C1 (C2). The time delay is determined by the combination R1/C1 (C2).
  • Page 309 Fig. 3.162: Circuit 162 – Needle pulse generator 4 kHz Fig. 3.163: Circuit 163 – Needle pulse generator 5 kHz Fig. 3.164: Circuit 164 – Jimi-Hendrix sound generator...
  • Page 310 Fig. 3.165: Circuit 165 – Guitar Distortion Fig. 3.166: Circuit 166 –FET lie detector with LED indicator Fig. 3.167: Circuit 167 –FET lie detector with moving-coil instrument...
  • Page 311 Fig. 3.168: Circuit 168 –FET lie detector with LED indicator Fig. 3.169: Circuit 169 –FET lie detector with moving-coil instrument Circuit 166 to 169: By means of the FET input level or a Darlington pair amplifier, a DC amplifier with very high input resistance is implemented.
  • Page 312 Fig. 3.170: Circuit 170 –Buffer amplifier for magnetic loop antenna Fig. 3.171: Circuit 171 –Buffer amplifier for condenser microphone Fig. 3.172: Circuit 172 – Simple HF generator without inductor...
  • Page 313 Fig. 3.173: Circuit 173: Electronic NF switch Fig. 3.174: Circuit 174 – Stabilizer for 1.4 V Fig. 3.175: Circuit 175 – Stabilizer for 2 V Circuit 173: The functioning principle is described on page 259.
  • Page 314 Fig. 3.176: Circuit 176 – Stabilizer for 3.6 V Fig. 3.177: Circuit 177 – Stabilizer for 4.4 V Fig. 3.178: Circuit 178 – Stabilizer for 5.2 V Circuit 174 to 178: A stable voltage divider (R1, R2, R3) creates a stable base bias for transistor T1. Constant current thus flows through the load resistor at the emitter.
  • Page 315 Fig. 3.179: Circuit 179: HF generator 150 kHz Fig. 3.180: Circuit 180: HF generator 420 kHz...
  • Page 316 Fig. 3.181: Circuit 181: Simple 7.5V battery monitor Fig. 3.182: Circuit 182: Simple 8.2V battery monitor Circuit 181 and 182: Resistors R3 and R4 (R5) form a stable voltage divider. The lower battery voltage is fed to the base of T2. At threshold, voltage is fed to base T2. T2 turns on, T1 is blocked, LED1 is off, if and for as long threshold voltage is exceeded (battery voltage is sufficiently high).
  • Page 317 Fig. 3.183: 183 Audio Fade-in and Fade-out Fig. 3.184: Circuit 184 – Peak level display with LED Fig. 3.185: Circuit 185 – Peak level display with moving-coil instrument...
  • Page 318 Fig. 3.186: Circuit 186: Acoustic conti- nuity tester Fig. 3.187: Circuit 188 – Active TTLCMOS probe with moving-coil instrument Circuit 186: The functioning principle is described on page 248.
  • Page 319 Fig. 3.188: Circuit 188 – Active TTLCMOS probe with moving-coil instrument Fig. 3.189: Circuit 189 – Simple active probe with Piezo element...
  • Page 320 Fig. 3.190: Circuit 190 – Simple active probe with moving-coil instrument Fig. 3.191: Circuit 191 – Simple active probe with Piezo element Fig. 3.192: Circuit 192 – Simple active probe with moving-coil instrument...
  • Page 321 Fig. 3.193: Circuit 193 – Simple IR transmitter Fig. 3.194: Circuit 194 – Simple IR receiver Fig. 3.195: Circuit 195 – constant voltage source Fig. 3.196: Circuit 196 – constant voltage source...
  • Page 322 Fig. 3.197: Circuit 197 –Class A amplifier with Piezo element Fig. 3.198: Circuit 198 – Infrared transmitter Fig. 3.199: Circuit 199 – Infrared receiver...
  • Page 323 Fig. 3.200: Circuit 200 – Iron-free push-pull output stage for Piezo element Fig. 3.201: Circuit 201 – 1 seconds switch- on delay Circuit 200: The functioning principle is described on page 290. Circuit 201 to 203: The functioning principle is described on page 252.
  • Page 324 Fig. 3.202: Circuit 202 – 3 seconds switch-on delay Fig. 3.203: Circuit 203 – 7 seconds switch-on delay...
  • Page 325 Fig. 3.204: Circuit 204 – Piercing siren sound with Piezo element Fig. 3.205: Circuit 205: Discrete Operational ampli- fier...
  • Page 326 Fig. 3.206: Circuit 206: Discrete Operational ampli- fier with Piezo element. Fig. 3.207: Circuit 207 – NOR gate with LED Circuit 207: The functioning principle is described on page 298.
  • Page 327 Fig. 3.208: Circuit 208 – NAND gate with LED Fig. 3.209: Circuit 209 – Active Zener diode 4V Circuit 208: The functioning principle is described on page 299. Circuit 209 to 211: The level of Zener voltage is monitored at the base of T2. T1 will reduce current, if voltage drops.
  • Page 328 Fig. 3.210: Circuit 210 – Discreet 5.2V Zener diode Fig. 3.211: Circuit 211 – Discreet 7.4V Zener diode...
  • Page 329 Fig. 3.212: Circuit 212 – Simple detector receiver Fig. 3.213: Circuit 213 – Improved detector receiver Fig. 3.214: Circuit 214 – Detector receiver with amplifier Fig. 3.215: Circuit 215 – Capacitor test with LED indicator...
  • Page 330 Fig. 3.216: Circuit 216 – Capacitor test with moving- coil instrument Fig. 3.217: Circuit 217 – Generating hydrogen Fig. 3.218: Circuit 218 – Generating hydrogen...

Table of Contents