12 Volt Dryfit Battery Charger with Automatic Shutoff

Circuit Diagram of Automatic shutoff battery charger.

Notes:     The circuit was built on Vero board and tested using a large value electrolytic capacitor instead of a battery.   The 500 ohm preset resistor sets the actual output voltage.   The 47k preset controls the hysteresis and sets the voltage at which the charger switches on again.   The circuit will cycle on and off and if correctly set will keep the battery charged without overcharging it.

Raymond Libreri 15/6/01