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Summary of Contents for Franzis UKW 65287
- Page 1 UKW-Radio Bausatz FM Radio Construction Set...
- Page 2 SIMPLIFIED EU DECLARATION OF CONFORMITY Hereby, FRANZIS Verlag GmbH declares that the radio equipment type FM Radio Construction Set, type number FRANZIS_Radio_001, is in compliance with Directive 2014/53/EU. The full text of the EU declaration of conformity is available at the following internet address: www.franzis.de/conformity...
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Page 3: Introduction
Introduction By assembling this radio, you will gain insights into electronics and experience a sense of achievement even early on. Explore the functionality of the individual components and gradually build a complex circuit. Finally, use the completed FM radio to listen to your local FM station in great sound quality! The FM radio is easy to assemble and yet offers... -
Page 4: Table Of Contents
Contents Introduction .................. 3 The Components ................ 5 Step 1: Mounting the Amplifier ............ 12 Step 2: Sound Generator .............. 16 Step 3: Improved Amplifier ............ 19 Step 4: Simple Radio .............. 22 Step 5: Tuning ................ 25 Step 6: Mounting in the Housing .......... 28 Troubleshooting ... -
Page 5: The Components
The Components The various circuits are built on a bread- board. The centre part contains 46 contact strips with five contacts each. The two long strips with 20 contacts along the edges are typically used to provide the operating voltage. Internal connection of the contacts... - Page 6 All components are inserted in the breadboard and thus connected to each other. The individual steps are illustrated with assembly drawings, photos or circuit diagrams. The symbols in the circuit diagrams are as follows: Battery Voltage regulator Loudspeaker FM board Capacitor E-capacitor Resistor...
- Page 7 The FM board is the essential component of this radio. It contains an integrated circuit and many tiny pre-soldered capacitors and resistors. You can easily recognise two printed coils and the upright variable capacitance diode. There are six pins to connect the board with the breadboard and thus the other components.
- Page 8 LM386 amplifier Loudspeaker The LM386 loudspeaker amplifier is an integrated circuit (IC) The loudspeaker exhibits a resistance of 8 Ohm and can in a housing with eight pins, numbered from pin 1 at the bot- tolerate up to 0.5 W. The volume depends mainly on how the tom left corner to pin 8 at the top left corner.
- Page 9 The loudspeaker must not be connected directly to the am- plifier but requires a capacitor. Any capacitor consists of two metal sheets insulated against each other. The electrolytic capacitor (e-cap) used here contains aluminium sheets in a conductive fluid (electrolyte). You have to pay attention to the mounting direction as 100 µF e-cap...
- Page 10 The resistors in the kit are of the carbon film type and can Basically, a potentiometer is a resistor; however, it contains a be mounted in any direction. The smallest one has a resis- third contact, which is shifted by turning the axis. The poten- tance of 100 ohm (100 Ω), the biggest one has 220 kiloohm tiometer will be mounted in the radio housing with a washer (220 kΩ).
- Page 11 The volume potentiometer contains an additional switch and thus has five connecting wires. By turning the axis to the far left, the radio is turned off. As a special feature of this poten- tiometer, the resistance curve is not linear but adapted to the human sense of hearing.
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Page 12: Step 1: Mounting The Amplifier
Step 1: Mounting the Amplifier Required components: Loudspeaker Breadboard, LM386 amplifier IC, 100 µF e-capacitor, 1 kΩ resistor (brown, black, red), hook-up wire 100 µF e-cap Strain relief LM386 amplifier Battery with clip 1 kΩ resistor (brown, black, red) - Page 13 The eight-legged LM386 IC is a loudspeaker amplifier suited for battery operation. Internally, it contains many transistors and resistors. Pin 4 of the IC (GND) connects to the negative termi- nal of the battery via a 1 kΩ resistor (brown, black, red) in order to limit the current in case of improper assembly.
- Page 14 Initially, the eight legs of the IC have a slightly widened stance and must be aligned in parallel rows. This is best done with pliers. Only now it is possible to insert the IC in the breadboard without effort. Be careful to mount the chip in the correct direc- tion.
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Page 16: Step 2: Sound Generator
Step 2: Sound Generator Required components: 10 kΩ resistor (brown, black, orange) - Page 17 This circuit uses the 10 kΩ resistor (brown, black, orange) to turn the amplifier into a sound generator. For natural oscillations to emerge, the non-inverting input at pin 3 of the LM386 has to be connected to the output via a resistor. This feedback gener- ates oscillations of the amplifier, which become audible in the loudspeaker as humming or clicking.
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Page 19: Step 3: Improved Amplifier
Step 3: Improved Amplifier Required components: 100 nF disc capacitor, 100 µF e-capacitor, hook-up wire... - Page 20 Capacitors are often used to transfer sound frequency signals. Here, we use a ceramic 100 nF disc capacitor (labelled 104). This amounts to just a 1000 of the capacitance of the 100 µF e-cap. A 100 nF capacitor is ideally suit- ed as a coupling capacitor at the amplifier input.
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Page 22: Step 4: Simple Radio
Step 4: Simple Radio Required components: TDA7088 FM IC receiver board, HT7530 voltage regulator, 10 kΩ resistors (brown, black, orange), 1 kΩ resistor (brown, black, red), 100 Ω resistor (brown, black, brown), hook-up wire... - Page 23 The receiver board with the TDA7088 FM IC is the heart of your FM radio. Apart from the IC, the board contains many tiny capacitors, a variable capacitance (varcap) diode and two printed coils. For the first experiment, only four pins are used. The stabilised 3 V operating voltage is supplied via GND (-) and BAT (+).
- Page 24 While there is still much to do to complete the radio, you may already be lucky and be able to receive a radio station. As the tuning contacts are not yet attached, you will receive a random frequency. However, by momentarily touching the +, S, R, and - contacts on the receiver board, you can switch to a different station.
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Page 25: Step 5: Tuning
Step 5: Tuning Required components: Hook-up wire... - Page 26 The radio IC has a scan input (S) to start the station scan. The corresponding push-button is placed between the positive oper- ating voltage and the S input. To build the push-button, you use hook-up wires that will connect the BAT terminal to the S input when they touch each other.
- Page 27 The receiver board also contains a variable capacitance diode (varcap) whose capac- itance changes depending on the applied DC voltage. The smaller the capacitance, the higher the frequency. The R pin of the radio board is connected to the varcap diode.
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Page 28: Step 6: Mounting In The Housing
Step 6: Mounting in the Housing Required components: Volume potentiometer, tuning potentiometer, 220 kΩ resistor (red, red, yellow), washers, cap nuts, hook-up wire, both rotary knobs, radio housing... - Page 29 The kit contains two potentiometers. The first one is intended to control the volume and additionally has a switch to turn the radio on and off. The second one will be used for tuning. Mount both potentiometers with their washers and cap nuts in the radio housing.
- Page 31 Connect the volume potentiometer instead of the previously used voltage divider made of two resistors. Also integrate the switch of the potentiometer with the negative battery connection, where previously a resistor or a wire had been attached. The second potentiometer will be used for scanning the frequencies. When the potentiometers are attached, you can close the housing and control the radio from the outside.
- Page 32 The tuning voltage set at the left potentiometer is applied via a 220 kΩ resistor (red, red, yellow) to the reset pin and thus to the varcap diode. When the wiper of the poten- tiometer is placed near +3 V, the resulting frequency is low.
- Page 33 The antenna consists of a wire loop as big as possible and is attached between A and GND. Use a wire with a length of 1 m. Thread it through the designated holes so that the antenna loop remains outside the housing.
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Page 34: Troubleshooting
Troubleshooting While assembling the radio, you might make a mistake that is On the other hand, when the loudspeaker does not emit any not so easy to spot. If this happens, do not give up but accept sounds, the usual suspects are the loudspeaker itself, the the challenge! When the radio doesn’t work, you should first amplifier and the volume control. - Page 35 Repeat the first radio experiment without a particular tuning. When you get a significantly different result at one of the It is sufficient to remove the middle connection of the poten- measuring points, the problem probably resides in the re- tiometer (blue).
- Page 36 Measured voltages...
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