Af Switch - Maker Factory ELECTRONICS EXPERIMENTS BOX Manual

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.
Experiment
The circuit uses the flow of a low frequency signal to turn an AF signal on or off.
If the switch is open, the AF signal can pass without problems. If -9V is applied, the power of an AF signal
is reduced by about 80 dB. The output signal is at approximately one ten-thousandth and is thus virtually
impossible to hear.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.173.
198
Components required:
1 x J111 FET transistor,
1 x 1N4148 silicon diode,
2 x 10 kΩ resistors,
2 x 22 kΩ resistors,
1 x 1 MΩ resistor,
2 x 10 μF electro-
lytic capacitors,
1 x breadboard, 1 x 9V
battery with clip con-
nector
Fig. 2.173: Electronic AF
switch