125
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
Components required:
1 x J111 FET transistor,
1 x 2N3904 transistor,
1 x 1N4148 silicon diode,
1 x 1 M
Ω
resistor,
2 x 22 k
Ω
resistors,
1 x 10 k
Ω
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
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.
Summary of Contents for ELECTRONICS EXPERIMENTS BOX
Page 4: ......
Page 265: ...267 Fig 3 56 Cir cuit 56 Audio limiter Fig 3 57 Circuit 57 Amplifier for a storm detector...
Page 269: ...271 Fig 3 64 Circuit 64 Stabilizer for 1 9 V Fig 3 65 Circuit 65 Stabilizer for 2 5 V...
Page 275: ...277 Fig 3 80 Circuit 80 Quiztimer 30 seconds Fig 3 81 Circuit 81 Handy diode tester...
Page 315: ...317 Fig 3 179 Circuit 179 HF generator 150 kHz Fig 3 180 Circuit 180 HF generator 420 kHz...
