AUTOMATIC LIGHT ACTIVATED LAMP

Automatic light activated lamp find use in many domestic and industrial areas instead of bothering one’s self about when to turn OFF or ON the light in an environment when the day is dark.
The system have its merit as to Low Energy Consumption ,Eradication Of Human Failure, Time Saving And Auto-switch From ON to OFF and vice visa.

Material required for its construction.

Resistor
Transistor
DIAC
Capacitors
Light emitting resistor
Lamp
Connecting wire
Soldering iron
Veroboard

Circuit diagram

Operation

When the mains input is switch on the AC voltage flows through R1 and C1 which helps to drop the voltage before getting to the bridge rectifier .the type of c1 capacitor is refer to as the x rated capacitor thus this type of Transformer less power supply is called Capacitor Power Supply.
The rectifier convert the ac voltage to DC which is then filter by capacitor C2,the voltage flow through R2 to meet R3D5C3C4 which are connected parallel the sink off spike thereby keeping the voltage supply at 10v as a result of the zener rating used.
This voltage is used to power RV1,LDR,R5 and Q1 all connected in a potential dividers mode, the output is couple to optoisolator U1 which have control over U2 to either switch off or ON via the sensitive of light from the LDR.
The TRIAC is connected in series with the lamp via the mains supply