162
Components required:
1 x 2N3904 transis-
tor, 2 x 1N4148 silicon
diodes, 1 x BAT85
Schottky diode,
1 x 4.7 k
Ω
resistor,
1 x 10 k
Ω
resistor,
2 x 22 k
Ω
resistors,
1 x moving-coil instru-
ment, 1 x breadboard,
1 x 9V battery with clip
connector
Fig. 2.136:
NAND gate with
moving-coil instrument
Experiment
If everything is wired correctly, both “switches” are in the
low
position. The potential at the output is
high
;
the moving-coil instrument needle is not moving. The following table, also called truth table, shows what
will happen now at the different switch states.
Input 1
Input 2
Output
Moving-coil instrument
low
low
high
no motion
high
low
high
no motion
low
high
high
no motion
high
high
low
full-scale swing
The states
high
and
low
at the inputs are achieved by toggling the respective switch. Unlike the previous
experiment, the states must be wired manually. In digital electronics, such a circuit with the behaviour
described above is known as
NAND gate
. A tablet or notebook PC contains tens of thousands of those
gates.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.136.
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...
