142
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,
1 x red LED, 1 x 1 M
Ω
resis-
tor, 2 x 220 k
Ω
resistors,
1 x 100
Ω
resistor,
1 x 10 k
Ω
resistor,
1 x 4.7 k
Ω
resistor,
1 x 2.2 k
Ω
resistor,
3 x 1 k
Ω
resistors,
1 x breadboard, 1 x 9V bat-
tery with clip connector
Fig. 2.117:
Off button with sensor
Experiment
If everything is wired correctly, the red LED will turn on once the battery is connected. This circuit is respon-
sive to a DC voltage amplifier with a high-resistance input. We use the bare end of the inserted wire jumper
as a sensor. When you touch the sensor surface with grease-free fingers, the red LED will turn off. If you use
a relay instead of the LED, you could turn off your lights or the audio system with just a tap of your finger.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.117.
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...
