Experiment 2 - The General Multivibrator

What are "multivibrators are cross-coupled digital circuits." or "Multivibrator consist of two mutually coupled electronic switches"?

Here you ask yourself the question of how to "cross-couple" or "mutually couple" two circuits. Take a look at the circuits shown.

General circuit diagram of an electronic switch.

General circuit diagram of a multivibrator.

In the circuit diagram shown on the left, the electronic switch is shown schematically. The circuit has two states. The transistor T blocks or switches through.

In the circuit diagram shown on the right, the electronic switches are cross-coupled by the coupling elements CE1 and CE2. In this way, the transistors are no longer independent. As a general rule...

• If the transistor switches T1 through, the transistor T2 blocks.
• If the transistor switches T2 through, the transistor T1 blocks.

The circuit thus switches between two states back and forth. This is a multivibrator.

But which coupling elements are used...?

Multivibrators with different coupling elements (CE).

You are exploring these circuits in the following experiments...