Experiment 2 - The NOT-Transistor Logic (RTL)

The next logical operation is the NOT logic. The corresponding logical circuit has only one input and one output.

The truth table shows you the NOT-logic. The result at the output Q negates the input A...

A Q 0 1 1 0 Truth table of the NOT logic.

NOT symbol in circuit diagrams.

Transistor circuit of an NOT logic. (Enlarge)

Circuit diagram of the NOT logic with a transistor.

Use to the transistor circuit shown as the logic unit.

• When the push-button switch S1 is open, (A = 0), the transistor blocks and a current flows through the resistor R2a and Q. The LED lights up (Q = 1).
• When you close S1 (A = 1), the transistor switches through and short-circuits Q. The LED goes out (Q = 0).

This is the logical behavior of a NOT circuit. In the next experiments you look at logic units with two inputs.