This Nicd charger circuit diagram is another simple NiCd battery charger, and I think its very interesting because uses LEDs to adjust the charging current.
As mentioned above, this Nicd charger circuit uses constant current LEDs to adjust charging current. It makes use of LEDs that pass a constant current of about 15 -mA for an applied voltage range of 2-18 V.They can be paralleled to give any multiple of 15 mA and they light up when current is flowing.
The circuit will charge a single cell at 15, 30 .or 45 mA or cells in series up to the rated supply voltage limit (about 14 V).
