Automatic Emergency Light
The circuit below is an automatic switch-on emergency light. With IC as automatic controller, and and over charger protector. This circuit will drive the light on when the main power from AC source dismissed.
IC1 (LM308) protect the batteries from overcharged. The inverter section comprises IC2 (NE555) that is applied in stable mode to generate sharp pulses / wave with frequency of 50 Hz to drive the power MOSFETs (IRF840).
Circuit Parts
R1,R4,R6,R8_______________________1K
R2_______________________________10/1W
R3_______________________________820
R5_______________________________10K
R7_______________________________100
C1_______________________________1000u/25V
C2_______________________________10u/16V
C3_______________________________0.01u
D1-D4,D7_________________________1N4007
D5,D8____________________________1N4148
D6_______________________________6.2V ZENER
T1_______________________________SL100
T2_______________________________2N2222
T3, T4____________________________IRF840
IC1______________________________LM380
IC2______________________________NE555
RL1______________________________6V,100Ohm
RL2______________________________6V,200Ohm
X1_______________________________200mA
[source:CircuitDiagram]