Four-Hour Timer

The following schematic diagram is four hour timer circuit. Feature : easy to build, 3 hours 53 minutes total time,9V supply voltage. Component : 555 timer IC, Resistor, capacitor, switch, transformer, LED, CD4040B, Relay, BC547 transistor, 1N418 diode, variable resistor. [wiredworld.tripod.com]

Smart Battery Charger Using A Single-Transistor Circuit

The following circit is a smart battery charger using a single transistor. Featre : Simple circuitry, 13.3 VDC supply voltage, single transistor. Component : Battery, resistor, C1061 transistor, 1N4001 diode, relay, capacitor, potentiometer. [electronicdesign.com]