Bistable Multivibrator using 555 Timer

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In this tutorial, we will show you how to make a Bistable Multivibrator circuit using 555 Timer IC. A bistable multivibrator has two stable states and it remains in the same state until and unless we apply an external trigger to the circuit. We also call these circuits flip-flops and latches. There is no RC timing network in a bistable circuit, so in order to control pulse width, we use an external trigger.

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Hardware Required

The following components are required to make Bistable Multivibrator Circuit

S. NO	Component	Value	Qty
1.	Breadboard	–	1
2.	Battery	9v	1
3.	Connecting Wires	–	1
4.	IC	NE555 Timer	1
5.	Resistors	10k, 220 ohm	2, 1
6.	Ceramic Capacitor	0.01uF	1
7.	Push Button	–	2
8.	LED	5mm	1

***Hardware for Bistable Multivibrator Circuit***

555 IC Pinout

For a detailed description of pinout, dimension features, and specifications download the datasheet of 555 Timer

Circuit Diagram

Connection

Make power connections by connecting Pin 8 to VCC & Pin 1 to GND.
Connect 0.01uF Capacitor at Pin 5.
Use a jumper wire to connect Pin 6 to GND.
Add a Push-button with a 10K Ω Resistor at Pin 4.
Add another Push-button with a 10K Ω Resistor at Pin 2.
Connect LED with 220 Ω Resistor at the output Pin 3.

Working Explanation

In this circuit, we have connected two switches at Pin numbers 2 & 4 in order to SET and RESET the output of the 555 timer. Resistors R1 & R2 are the pull-up resistors for these switches. When the switches are open Pin 2 & 4 will be in the High state and when the switches are closed, these Pins will go to a Low state. If we want to output at Pin 3 to be High, we will only close the switch connected to Pin 2 while the switch connected with Pin 4 will remain open.

Resistor R3 is connected in series with the LED at the output Pin 3. It acts as a current limiting resistor for the LED. Capacitor C1 is connected to Pin 5 of the 555 timer in order to avoid high-frequency noises.