SWITCH_OPERATED_TURNOFF_TOUCH_SWITCH

Published:2009/7/14 20:08:00 Author:May | From:SeekIC

When S1 is closed,the circuitry is on in standby mode.When the touch plate is touched,the output of the 555 time IC1 goes high,supplying a positive potential to the base of transistor Q2,aiding its bias,The transistor is then on,allowing current to flow through pin4,5 and 6 of IC2.The gate of the SCR is then triggered,the relay is energized,and its contacts turn the ac bulb on.To turn the bulb off,just press S2(RESET),which disconnects the ande of the SCR from the positive supply,turning it off and deenergizing the relay,The light-dependent resistor(R7)is used if you want to turn on the circuit remotely.Just point a flashinght at R7 to decrease its resistance,leaving only the 1000Ω resistor as the base resistance.The resistance give the base a positive positive potential,forward biasing the emitter-base junction of transistor Q1.Transistor Q2 is also turned on because its base is made positive by Q1,which triggers SCR1,energizing the relay.



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