212
2.88 Logic probe
Circuit 187:
Active TTL CMOS probe with LED display
Setup information
Install the two transistors, the four diodes and the four resistors as shown in
Fig. 2.187
The seven jumper
wires come next. Check the placement on the board again and only then connect the battery.
Components required:
2 x 2N3904 transis-
tors, 2 x 1N4148 silicon
diodes, 1 x green LED,
1 x red LED, 3 x 1 k
Ω
resistors, 1 x 10 k
Ω
resistor, 1 x breadboard,
1 x 9V battery with clip
connector
Fig. 2.187:
Active TTL CMOS
probe with LED display
Experiment
If the level is between 0V and +2V at the tip of the probe, the red LED is lit, at a level b4V and +5V,
the green LED is lit.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.187.
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...
