Maker Factory ELECTRONICS EXPERIMENTS BOX Manual page 231

The high state of the inputs is caused by closing the respective switch at the high position. In digital elec-
tronics such a circuit with the behaviour described above is known as NOR 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. 3.207.
Circuit 208: NAND gate with LED
Setup information
Install the two transistors, the four diodes and the three resistors as shown in Fig. 2.208. The seventeen
jumper wires come next followed by the jumpers, which serve as switches (shown dashed). For your guid-
ance we have labelled the switches with high E1, low E1 and high E2, low E2. Check the placement on the
board again and only then connect the battery.
Experiment
If everything is wired correctly, both "switches" are in the low position. The potential at the output is high;
the red LED is lit. The following table, also called truth table, shows what will happen now at the different
switch states.
Components required:
1 x 2N3904 transistor,
1 x 2N3906 transis-
tor, 2 x 1N4148 silicon
diodes, 1 x BAT85
Schottky diode, 1 x red
LED, 2 x 1 kΩ resis-
tors, 1 x 10 kΩ resistor,
1 x breadboard, 1 x 9V
battery with clip con-
nector
Fig. 2.208: NAND gate with
LED
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