this is an instructable how to make a timer circuit.
what you need:
220 uf cap
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once you have all the parts you can solder everything together and make the circuit.
it's verry handi to have a soldering iron with the proper equipment :p
BE CAREFUL WITH THE TRANSISTORS THEY CAN GET DAMAGED BY THE HEAT OF YOUR SOLDEREING IRON!!
once everithing is soldered together you can test the circuit bij puching the switch and watch what happends. you can change the time with the potentiometer(variable resistor). have fun and be safe.