Thursday, August 21, 2014
astable multivibrator circuit using two transistors (led flasher)
INTRODUCTION
Astable multivibrator circuit is a circuit whose output level is not stable.
the output of the circuit is high and low alternately. the circuit below is very
interesting and there are two leds which glows turn by turn. ie they blick turn by
turn.
CIRCUIT DIAGRAM
WORKING OF THE CIRCUIT
the above circuit work based on two properties of the two components.
1. capacitor stores charges when DC is applied across it.when charging a capacitor,
direct current flows through capacitor.when capacitor is charged two third,
then current stops flowing. when its discharged upto one third then current
again flows through it.
2. when current is supplied to the base region of the transistor, then current starts
to flow from collector to emitter of the transistor because transistor is current
controlled device. This condition of the transistor is called saturation. again
when base current is not supplied to the transistor, then current doesnot flow
through collector to emitter of the transistor which is called cut off ..
lets look at the following diagram
when capacitor 1 is charging
note that led2 is glowing since transistor 1 gets base current when capacitor 1 is
charging being transistor 1 on...
when capacitor 2 is charging
still if you have any confusion about making this circuit, you can comment here...
thanks for your visit in this blog.
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