Electronic Potentiometer - Maker Factory ELECTRONICS EXPERIMENTS BOX Manual

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. You can significantly increase the sensitivity of the Piezo
element by using a sound plate or even a sound box. Read more about it in Chap. 1.2.3
Experiment
An electronic level control is used to determine the weakening of an audio signal by means of the control
voltage value. In our present case, at 0 V control voltage, the audio signal will be amplified by the Factor 10;
at -5 V control voltage will be muted by a factor 100, at -5 V control voltage is muted by the factor 100. The
maximum output voltage is about 0.5 V. As sources for the (negative) control voltage you could use batteries
such as 1.5V, 3V, 4.5V batteries or a suitable variable power supply.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.100.
Components required:
1 x J111 FET transistor,
1 x 2N3904 transistor,
1 x 1N4148 silicon diode,
1 x 1 MΩ resistor,
2 x 22 kΩ resistors,
1 x 10 kΩ resistor,
2 x 10 μF electrolytic
capacitors, 1 x Piezo ele-
ment, 1 x breadboard,
1 x 9V battery with clip
connector
Fig. 2.100: Electronic level
control
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