Instructions

234
Input 1 Input 2 Output LED
low low high dark
high low high dark
low high high dark
high high low illuminated
The states high and low at the inputs are achieved by toggling the respective switch. In digital electronics
such a circuit with the behaviour described above is known as NAND gate. A tablet or notebook PC con-
tains tens of thousands of those gates.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.208.
2.99 Active Zener diode
Circuit 209: Active Zener diode 4V
Setup information
Install the two transistors and the six resistors as shown in Fig. 2.209. The thirteen jumper wires come next.
Check the placement on the board again and only then connect the battery.
Components required:
1 x 2N3904 transistor,
1 x 2N3906 transistor,
2 x 1 kΩ resistors,
2 x 10 kΩ resistors, 2 x 100
kΩ resistors, 1 x breadboard,
1 x 9V battery with clip con-
nector
Fig. 2.209: Active Zener diode 4V