AUTOMATIC TRAFFIC CONTROL LDR SCHEMATIC DIAGRAM
When the light is dark (high resistance value of LDR), electric current is small. Since the electric current is small and it value less than the transistor’s active voltage, the electric current will be blocked, AC lamp circuit closes, and the light turns on. When the light is bright (low resistance LDR value), electric current is high. Since the electric current is high and its value is larger than the transistor’s active voltage, the electric current passes, relay turn ON position, AC lamp open, and the light turns off.
Components list :
R1 : LDR
Resistor Variable R : 10k ohm
R3, R4 : 1k ohm
Q1, Q2 resistor : 2N2222
Relay K1 : 9V relay type SPDT
L1 : Bulb lamp 220V AC
Fuse F1 1 Ampere
9V power supply
