This is the diagram of 6V Gel Cell charger. The circuit is using NE555 timer as oscillator and TPI31T switching transistor. The schematic diagram designed by Tony Van Roon.
Parts List:
R1 = 22 ohm, 1W
R2 = 270 ohm R3 = 220 ohm *R4 = 715 ohm, 1% *R5 = 3.57K, 1% *R6 = 1.40K, 1% *R7 = 1.47K, 1% | C1 = 100nF
C2 = 100nF D1 = 1N4001 T1 = TIP31A, B, C (or equivalent) U1 = Timer IC NE555V (or equivalent) S1 = Toggle switch, ON-OFF |
6V Gel Cell Charger circuit source page