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You are here: Home / Replies / this circuit is simply a

this circuit is simply a

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Electronics › Electronics › Explanation of this Electronic circuit › this circuit is simply a

May 13, 2012 at 1:39 am #7777
Mehtab Ali
Participant

this circuit is simply a switch. when the sensor senses the ir radiations it sends a current to the base of microcontroller, thus turning the transistor on and hence 

their is zero volts at the ‘o/p to 8051’ pin. similarly when their is no current coming from the sensor then the transistor is off and the o/p is high at 5v.

  The 10k resistor is choosen in such a way to keep the transistor in the saturation region if a current is applied at the base i-e Vce<0.7v.

because for transistor to be operated as a switch, it should be operated in cutoff and saturation region.

The other resistor is used for proper biasing of transistor.

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