Introduction
A monostable multivibrator is a synchronous or asynchronous sequential circuit that is widely used in electronic circuitry. Certainly, Multivibrators are from the family of oscillators that are often known as relaxation oscillators. They have two stable states which are the input high state and the output low state. But, 555 Timers as Monostable Multivibrators are those that have only one stable state and that’s the reason, they are known as Mono. When the negative pulse is applied at the input trigger pin of the IC, the positive rectangular pulse is generated at the output.
The monostable mode has another name which is ‘one-shot mode. It implies that after the IC gets triggered, it gives only one output pulse. When the time interval reached a certain stage, the output pulse stops until the other triggered pulse comes. During this, the triggered pulse generates a single output pulse. In short, we are going to design a monostable multivibrator using a 555 timer IC.
Hardware Required
| S.no | Components | Value | Qty |
|---|---|---|---|
| 1. | Breadboard | – | 1 |
| 2. | Timer IC | NE555 | 1 |
| 3. | Resistor | – | – |
| 4. | Capacitors | – | – |
Circuit Diagram
Working Explanation of 555 Timer as Monostable Multivibrator
When there is no triggering, the output is low at the output terminal of IC pin 3 and the circuit is in a stable state. If applies the negative pulse is to an IC, the trigger input goes below one-third of the applied Vcc, this resets the flip-flop of the IC and the transistor goes into the cut-off state, and the output pin 3 goes high, the capacitor starts charging through resistor RA. When the capacitor gets slightly greater than two-thirds of the applied voltage, the output of comparator 1 in the IC goes high and sets the flip flop, and the transistor goes into the saturation state so, the capacitor starts discharging and output goes low.
Application and Uses
- In delay and timing circuit
- To drive the pulse generator
- In regenerating old signal pulse
