Instructables
Picture of Astable Multivibrator
The Astable Multivibrator is a really important circuit in electronics. This circuit deploys a signal back and forth between transistors. This circuit can be used for example in emergency lights. The circuitry presented in this instructable shows the symmetric characteristics of this circuit. 

You will need two 10KΩ, two 1KΩ resistors, two LEDs, two 47µF, two 2N2222 transistors, 9V battery, breadboard and jumper wire. 
 
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Step 1: Connecting power

Picture of Connecting power
Configure your breadboard to have the power from battery.  Connect positive with positive lines and if you want you can connect a LED and resistor to the main input just to make sure there is power as seen in the photo.

Step 2: Connecting transistors

Picture of Connecting transistors
Connect the transistors as seen in the image. Please connect them vertically, remember horizontal lines are connected. 

Step 3: Connecting transistor

Picture of Connecting transistor
Connect bottom N type end of the transistor to negative as shown in the photo.

Step 4: Connect Resistors

Picture of Connect Resistors
Connect resistors to the other N type end and to positive, also connect resistor to P type to positive. 

Step 5:

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Put everything together. 

The video of the circuit  working :) 

http://www.youtube.com/watch?v=n7gZGF5UxtE




Source Link:

http://en.wikipedia.org/wiki/File:Transistor_Multivibrator.svg
pfred21 year ago
One of my favorites. I wrote an article about it for here a couple of years ago. But I gave my article a funny title. It is the same circuit though.

http://www.instructables.com/id/Blink-LEDs-with-Discrete-Parts/