Photocell or auto dark activated switch using for running garden or street lights in the night and turns them OFF at the day time automatically so it helps to power saving.
The traditional photocell has two problems:
1-Standby power loss (around 1.6W)
2-Has 3 wires which is difficult to install
I designed and make a new circuit that haven't those two problems.
Parts list:
IC 4093
SCR c106m
LDR
Bridge diode 4A
Resistor 1M
Resistor 30K
Zener diode 9.1V 1/4W
Circuit diagram:
Important notes:
1- For this circuit you can only use SCR with sensitive gates such as BT169 or C106M
2- The IC used in this circuit is 4093 because it is micro-power IC, you can't use other NAND or NOT gate ICs.
3- Max. Load this circuit can handle is depend on SCR and bridge diode. The circuit can handle about 4A if used SCR C106M and 4A Bridge diode.
4- This circuit deal with 110/220V AC so can be very dangerous if you touch any component in the circuit.
5-If your lamp flickering you can add a 100nF ceramic capacitor between pin 7 and pin 14 of the IC.
Video:
