Description of Multivibrators

Multivibrators are simple circuits that have two states and are often used in digital logic, but they work mostly in an analog way.

Monostable Multivibrators: Also called "one-shots," these have one stable state. When you give them a trigger signal, they switch away from this state for a certain period, which is usually set by a connected capacitor. They're great for things like de-bouncing switch contacts.

Astable Multivibrators: These don't have a stable state. They keep switching between two states continuously, with the speed of switching usually determined by a connected capacitor.

Frequently Asked Questions

What does a multivibrator do?

A multivibrator is an electronic circuit that creates square or rectangular waveforms. You might also hear it called a nonlinear oscillator or function generator. It usually consists of two amplifiers set up with feedback to keep it running.

What are the three types of multivibrators?

The three types are:

Bistable: This one has two stable states and can act like a basic memory element.

Monostable: It has one stable state and produces a single pulse when triggered.

Astable: This type continuously switches between two states, creating a square wave output.

Digital integrated circuits are commonly used for these, but you can also make simple versions with discrete transistors.

Why is the multivibrator called 555?

The 555 Timer is named for its internal design, which includes three 5kΩ resistors connected together. These resistors form a voltage divider network between the supply voltage (pin 8) and ground (pin 1).

What are the disadvantages of a multivibrator?

For an astable multivibrator:

• It absorbs more energy.
• The output signal has low energy.
• It can’t achieve a duty cycle greater than 50%.

Is a Flip-Flop a multivibrator?

Yes, a Flip-Flop is sometimes called a bistable multivibrator. It's a data storage element that changes its state on the rising or falling edge of a clock signal. It has two stable states.

What types of devices use a multivibrator?

Multivibrators can be implemented with various devices, such as transistors, neon lamps, and tunnel diodes. They are used in circuits where you need waveforms rich in harmonics.