Solar-cell NiCad Charger

Additional Notes
The MAX639, made by MAXIM, has its own current limitter build in, set for 200mA. Plenty! Make sure that the charging NiCads can handle the contineous current of 200mA, for example, NiCad battery packs of 1700+ mA used for R/C (Radio Control) cars and electric aircraft. The solar cells used were of an older type (Bt2) but these days almost anything will work. The 1N5117 diodes are the 3-Watt hermetically sealed zener diodes. I may have to redesign this circuit (which is not my own design) to work with more common available diodes.