The circuit in Fig 1 fast-charges 500-mAhr AA NiCd cells. Depending on the setting of SW1 and SW2, the circuit handles two to eight cells, providing the circuit’s input voltage is at least 15V; at higher voltages, power IC3 from IC2′s pin 15. Charging starts when you plug in the battery. When the battery is fully charged, LED1 extinguishes, and the charger switches to trickle-charge mode.
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