Solar NiCad Charger


Parts List:
   R1 = 820K, 1%
R2,R3 = 75K, 1%
   R4 = 1M, 5%
D1,D2 = 1N5817, Schottky diode, or NTE585
   L1 = 100uH, coil
   U1 = MAX639, integrated circuit
   C1 = 100uF/40V, Electrolytic capacitor
   C2 = 47uF/40V, Electrolytic capacitor
Additional Notes:
The MAX639 has its own current limiter build in, set for 200mA. Plenty! Make sure that the charging NiCads can handle the continuous current of 200mA, for example, NiCad battery packs of 1700+ mA used for R/C (Radio Control) cars and electric aircraft.

The schematic is copyright © by Maxim and used with permission. However, the diagram as shown on the Maxim website, has a problem. It shows incorrect values for D1/D2 diodes (1N5117). I updated this value to 1N5817. -Tony

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