This is the Simple Over Voltage Protector Circuit Diagram. The whole circuit of over voltage protector is build and fabricated around operational amplifier used as comparator. The inverting input is given to pin 2 of op-amp IC (IC1) with reference voltage of 5.1V from zener diode. Similarly, non-inverting input is given to pin no 3 of IC1 use as sensor for over voltage protector for sensing voltage fluctuation in the mains. The two transistors T1 and T2 conduct alternating (i.e. one at a time) according to the voltage of mains.
Simple Over Voltage Protector Circuit Diagram
When voltage is around or below 240V AC transistor T1 is in off-state where T2 energized relay RL1. Similarly, when voltage becomes beyond 240V (i.e. above 240V) T1 is in conducting-stage and T2 is in off-stage which de-energized the relay RL1 and switch-off the appliance.
PARTS LIST
Resistors (all ¼-watt, ~+mn~ 5% Carbon)
R1 = 147 Ω/2W
R2 = 100 Ω/1W
R3 = 330 Ω
R4 = 100 KΩ
R5 = 1.8 KΩ
R6, R7 = 1 KΩ
VR1 = 10 KΩ
VR2 = 22 KΩ
Capacitors
C1, C4, C5 = 0.01 µF
C2 = 1000 µF/25V
C3 = 100 µF/25V
Semiconductors
IC1 = µA741 (Operational Amplifier)
IC2 = 7812
T1= BC547
T2 = SL100
D1, D2, D3, D4, D5 = 1N4007
D6 = 1N4148
ZD1 = 5.1V zener diode
Miscellaneous
X1 = 230V AC primary to 7.5V-0-7.5V, 1A secondary transformer
RL1 = 12V, 200Ω 1 C/O Relay
LED1 = RED
