Bistable Multivibrator using IC 555 timer

A bistable multivibrator has 2 stable states. It changes its state with respect to the trigger input applied to its trigger pin. Two stable states are high and low. There are many ways to make a bistable multivibrator using passive components but using 555 is a very easy task.

IC555

Pin configuration and some other useful data can be obtained from the Datasheet of lm555..click here to download datasheet of lm555. (courtesy: Texas Instruments).

Circuit Diagram:

Bistable Multivibrator circuit diagram

The above circuit is implemented on proteus software one needs to have the application installed in your pc if you want some real time simulation or directly implement circuit on the breadboard.

Note: There are 2 push-buttons. The left one is for SET and the right one is for RESET.

Components Required:

  1.  IC 555 Timer
  2. 10kΩ resistor (2pcs)
  3. 470Ω resistor
  4. 10nf capacitor
  5. 2 push-buttons
  6. led
  7. 10v power supply
  8. and brain….:):).

 Connections

  1. Supply Voltage: 10v supply is provided at the vcc pin ie. 8th pin of 555.
  2. 10k resistor connected to 8th pin and to a push button and the same push button connected to 4th pin and other teminal of push button connected to ground.
  3. 10k resistor connected to 8th pin and to a push button and the same push button connected to 2nd pin and other teminal of push button connected to ground.
  4. 1nf capacitor connected between ground and 5th pin.
  5. Led connected at the output.
  6. 470 ohm reststor is just used for current limiting.

10k resistors are used for pull up that means to provide both the pins high voltage when switches are not used. You can even use other resistor.

Output:

Turn ON the simulation and press the left push button. You will see that led glows. That means that your output is high. The push-button is released and still you can see that led glows which can be said that it is a stable state and output remains stable at high. Now when you press a right push button the output goes low and the led turns off. This is the second stable state and it remains in this state till you set the output high.

Read Here [555 as square wave generator or astable multivibrator].

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