Circuit Simulator - Astable Multivibrator (Oscillator)

Why Astable Multivibrator (Oscillator)?

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How to design a Astable Multivibrator (Oscillator) (electronic circuit)?

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Circuit Description:

This circuit is an astable multivibrator, or oscillator. The two transistors are cross-coupled in such a way that the circuit switches back and forth between two states. In one state, the base of Q1 is about one diode drop above ground, allowing a base current to flow. This keeps Q1 switched on, in saturation mode, allowing a current to flow through the collector, keeping Q1's collector voltage low, and discharging C1. Q2 is switched off, because its base voltage is not high enough to switch it on.

As the collector current into Q1 charges C1, the base voltage for Q2 goes up, until it is high enough to switch on Q2, causing a current to flow through its collector, which drops the collector voltage (the current causes a voltage drop across the resistor above it). The right side of C2 has dropped, but the voltage across it hasn't changed, so this causes Q1's base voltage to drop below ground, switching it off.

Then we get the other half of the cycle, with current flowing through Q2. This continues until Q1 turns on, and then the cycle repeats. -- Credits: Mr. Paul Falstad.





Ighodaro Triumphant said: (Jan 27, 2012)  
Plz! I need the principle of operation for this ciruit.

Arushirai75@Gmail.Com said: (Jan 26, 2013)  
What do you mean circuit switches back and fourth between two stages?

Dilip said: (May 31, 2013)  
Where I set the output?

Bitrus Yunusa said: (Sep 3, 2013)  
What is the used of R3 and R4?

Dheeraj Rai said: (Feb 25, 2014)  
What are R1 and R2 ?

Pranav said: (May 6, 2014)  
R1 and R2 are the voltage dividers, which stabilize the network.

Walks said: (Jul 6, 2014)  
Need to know where this circuit is applicable.

Thaveshni said: (Aug 6, 2014)  
Just try building the circuit. But put an LED between each of the 330 ohm resistors and capacitor. You will see that the LEDS blink one at a time. I recommend using a 33uF capacitor in order to see each LED blink.

Niusha said: (Dec 28, 2014)  
In Which multivibrator we can use one transistor?

And Who we can simulate multivibrator with one transistor?

Gojunpyo said: (Apr 5, 2015)  
Does it not produces the complete square waves?

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