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.

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.