This project will give a step by step instruction on constructing a cheap soldering iron with variable temperature control. Caution should be taken since you will be working with live house hold AC current.

The tools you will use a screw driver, wire stripper or diagonal cutter and tin snips. The materials are 4” X 4” box outlet, connectors, switch covers, 600W light dimmer rotary type and incandescent bulb used for testing.

Knock out one of the holes of the outlet box. Use the center hole to give you maximum room to place the components. Connect thru the punched hole the connector and thread the lock nut as much as possible using your fingers, not the wire clamp. Separate the wires and peel each cord with the diagonal cutter or wire stripper, the copper should show about half inch. Cut the aluminum excess of the lamp dimmer. Connect the components, isolate the “hot” wire, usually labeled and screw it to the brass screw of the outlet. Get the other wire and attach it to the dimmer using the wire nut. Now the last one is white or neutral wire screw it on the silver screw of the outlet. Get the ground wire from the pig tail and the dimmers ground and attach the terminal of the outlet.

If you got confused, don’t be alarmed, the light dimmer comes with a wiring diagram, just replace the bulb in the diagram with the outlet and the wiring is the same. Be sure that all the wires and components are nicely placed and there are no short circuits inside the box. Put a little loop on the pigtail inside the box before tightening the screws down to hold the pigtail firmly. Start testing, get a lamp shade using incandescent bulb and plug it in. When you rotate the knob it should go from bright to dim and vise versa. If it operated as it should then it is finished.

http://www.instructables.com/id/10ish_DIY_Variable_Temp_Soldering_Iron_C...