A multivibrator is a circuit that has two stable states. Each stable state is represented by a voltage e.g 0Volts and 5 volts. The astable variety is when the output. Astable and Monostable Multivibrator Using Timer IC modes: Astable, Monostable and Bistable IC as an astable multivibrator is a. The name mutivibrator designates a group of the circuits widely applied for switching as shift registers or temporary memories and as square.

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In the charging capacitor equation above, substituting:. In the monostable multivibrator, one resistive-capacitive network C 2 -R 3 in Figure 1 is replaced by a resistive network just a resistor. The capacitor discharges multivibrtaor resistor R and charges again to 0. The forward-biased Q2 base-emitter junction fixes the voltage of C1 right-hand plate at 0.

Leave a Reply Cancel reply Multtivibrator email address will not be published. Hence, when the circuit is switched on, if Q1 is on, its collector is at 0 V.

In the end, only R3 provides the needed input base current. At the same time, the other empty capacitor quickly charges thus restoring its charge the first capacitor acts as a time-setting capacitor and the second prepares to play this role in the next state.

During State 2Q2 base-emitter junction is forward-biased and capacitor C1 is “hooked” to ground. In this circuit none of the two transistors reach at stable state. In this circuit, a triggering signal is required to induce transition from stable to quasi stable state. The pulse width T of a monostable multivibrator is calculated as follows: In this configuration, one coupling network provides AC coupling while the other provides DC coupling. From Wikipedia, the free encyclopedia.

The diode D1 clamps the capacitor to 0. The first trigger causes conducting transistor to cut-off mode and second trigger causes it back to conducting mode. It is also called free running relaxation oscillator. The resistance R3 is chosen small enough to keep Q1 not deeply saturated after C2 is fully charged. It is implemented by the coupling capacitors that instantly transfer voltage changes because the voltage across a capacitor cannot suddenly change.


As Q2 base-emitter junction is reverse-biased, it does not conduct, so all the current from R2 goes into C1. For example, before the advent of low-cost integrated circuits, chains of multivibrators found use as frequency dividers.


The circuit is useful for generating single output pulse of adjustable time duration in response to a triggering signal. A division ratio of 10, for example, is easy to obtain but monostalbe dependable. The name mutivibrator designates a group of the circuits widely applied for switching as shift registers or temporary memories and as square were timing oscillator or clocks.

It can remain in either of these two states unless an external trigger pulse switches it form one state to the other. It has only one stable state. The duration of state 1 low output will be related to the time constant R 2 C 1 as it depends on the charging of C1, and the duration of state 2 high output will be related to the time constant R 3 C 2 as it depends on the charging of C2.

multivibrators:astable,monostable and bistable with applications

As a result, the circuit goes in State 1 described above. Unsourced material may be challenged and removed. Difference between astable monostable and bistable multivibrator Posted by: This is a comparator circuit and hence, the output becomes -V sat.

This latch circuit is similar to an astable multivibrator, except that there is no charge or discharge time, due to the absence of capacitors. Mechanics and its different branches in physics. For example, if Q2 is on and Set is grounded momentarily, this switches Q2 off, and makes Q1 on. It can be switched to quasi stable state by an external bbistable but it returns to the stable condition after multivibrstor time which is determined by the components of circuit.


Applications astable multivibrator applications of multivibrator astable multivibrator bistable multivibrator monostable multivibrator multivibrator types of multivibrator uses of multivibrators. Learn how your comment data is processed. Its collector voltage begins rising; this change transfers back through the almost empty C1 to Q2 base and makes Q2 conduct more thus sustaining the initial input impact on Q2 base. Other names of monostable multivibrator are delay multivibrator and unimultivibrator.

The circuit has one stable state and one quasi stable state. Q2 is on and connects the right-hand positive plate of C2 to ground.

For the circuit in Figure 2, in the stable state Q1 is turned off and Q2 is turned on. Operational Amplifiers, 2nd Ed.

Multivibrator – Wikipedia

This results into positive feedback due to overall phase shift of degree or 0 degree. It is a predecessor of the Eccles-Jordan trigger [7] which was derived from the circuit a multifibrator later. The diode will now get reverse biased and the capacitor starts charging exponentially to -Vsat through R.

A multivibrator is an electronic circuit used to implement a variety of simple two-state [1] [2] [3] devices such as relaxation oscillatorstimers and flip-flops. The output voltage of the switched-off transistor Q1 changes exponentially from low to high since this relatively high resistive output is loaded by a low impedance load capacitor C1. These circuits are basically closed loop feedback circuits operating with the feedback.

Pulse And Digital Circuits.