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Electronic mailbox front door

2018-01-23 01:26  
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This circuit is integrated electronic mailbox,A front door open.And when people open. Cabinet photo detector attached to the light, it will work.
Operation of the circuit.While not open the mailbox PHOTO1 will not bias. The voltage at C2 is approximately 9 volts, it is charged through R3.
The BE voltage of Q1 is not enough leg to bias the Q1 does not work. When open mailbox PHOTO1 to work, the voltage at C2 is “0″. The C2 begin to charge new.Between the C2 begin to charge the pressure to bias the BE pin of Q1. It works to stimulate the G pin of SCR1.The C1 is noise signal protection.When SCR1 to work to work and hold a current flows through LED1.LED1 light makes it through until the switch S1.To start a new cycle.

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