Experiment 1 - ID-Transistor Logic (RTL)

The simplest logical operation is the identity-, or ID-logic. For this you can make use of a transistor circuit.

The truth table shows you the ID logic. The result Q follows the input A...

A	Q
0	0
1	1

Truth table of the ID logic.

ID-symbol in circuit diagrams.

Transistor circuit an ID logic. (Enlarge)

Circuit diagram of the ID 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 the LED remains dark (Q = 0).
When you close S1 (A = 1), the transistor switches through. The LED lights up (Q = 1).

You could replace the circuit simply by a wire. The ID logic is actually so simple that it is often not even discussed.

However, this circuit is helpful in the understanding of transistor logic. Therefore pay attention to what is changing in the next circuit.

Resistor-Transistor Logic

The illustrated logic circuit uses only resistors and transistors. This group of logical circuits is therefore called resistor-transistor logic and commonly abbreviated with RTL.

Experiment 2 - NOT Logic (RTL)