# Automatic Battery Charger Circuit Schematic Diagram

This circuit is used to fill up the accumulator. When the accumulator is already depleted, the current flows through D3 is low, therefore make the T1 off. IC1 output will be low, therefore T2 and T3 basis current will be determined only by P1 position.

If the accumulator voltage is between 10 and 14 volts, D3 will gain forward current and T1 will be ON. IC1 output stays low thus the filling process determined by P1 and P2. If P3 voltage exceed zener D1 voltage, with positive feedback through R4, the output of IC1 will go to the value determined by the voltage of Zener D1 and D2. As a result, T1 will be off and the filling process depends on the position of P1.Here is the schematic :

Estimated price : $7

Component list :

R1 : 12k ohm

R2 : 10k ohm

R3 : 82k ohm

R5=R6=8k2 ohm

R7 : 100 ohm

R8 : 3k9 ohm

R9 : 4k7 ohm

P1 : 100k ohm, trimpot

P2 : 220k ohm-250k ohm, trimpot

C1a=C1b=4700 uF/40V

T1 = TUN

T2 : 8D138, BD140

T3 : TIP2955

D1 : 6V8, 400mW zener diode

D2 : DUS

D3 : 5V6, 400mW zener diode

IC1 : 741

Power transformator 16V/8 A

B : Bridge diode B80C 1.000

Slow fuse 1/2 A

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