Nickel cadmium charger circuit diagram

This circuit uses a constant current LED to regulate the charging current . Use a constant current LED of greater than 15mA when the external voltage is 2-18V . These light-emitting diodes can be connected in parallel to provide multiples of 15mA current, and these light-emitting diodes will light up when the current passes through. This circuit will charge a single battery at 15, 30 or 45mA, or batteries connected in series to reach the rated supply voltage limit (approximately 14V).