This circuit is integrated electronic mailbox,A front door open.And when people open. Cabinet photo detector attached to the light, it will work.
The Simple circuit using SCR and transistors
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.
Electronic mailbox circuit front door with ic 555
Living in the current rush to waste time to even have little value. Electronic circuits, so one is important in everyday life.Which saves time and convenience.
For example, this circuit. It gives us no time to wait to check voice mailbox.We see the LED is just enough.
Operation of the circuit. While no letter LDR will receive light from the lamp. The LDR resistance is very low. Resulting in IC does not work.
There is no output from the 3 pin. It make the current flows through R2, LED2 into three legs of IC1.The light LED2.But when a letter in the mail box to shield the light from the lamp. The LDR is not light. LDR will be much resistance.Voltage drop across the LDR is high enough to make IC1 work.
IC1 to produce frequencies from 3 pin. The light LED1.
Up to $20 shipping discount on first order now: https://jlcpcb.com/quote