DIY Temperature Control

After pricing a variable temperature control soldering iron ($99), I decided that there had to be a cheaper way. For less than $15, you can not only get a cheap Harbor Freight soldering iron but also the parts to make a temperature control that will also work for a wood burner.


  • 4″ square box – $1.29
  • 4″ square box cover (receptacle and switch opening) – $1.89
  • 15A receptacle – $0.79
  • 600W dimmer for incandescent lamp – $4.77
  • 1/2″ box connector – $1.29 (bag of ten)
  • Power cable – one for a PC works great and you probably already have one laying around

Warning, electricity is dangerous! Treat every wire as it is a live circuit and double check that power is disconnected from what you’re working on before using touching it. If you are uncomfortable working with electricity, do not do this project. Never leave a soldering iron, wood burner, or this temperature control unattended. Make and use this project at your own risk.

First knock out a 1/2″ opening in the box. The easiest way is to use needle nose pliers and “stab” inwards and then twist the blank out.



Insert the 1/2″ box connector into the opening and tighten.


Prepare the power cable by cutting it to the desired length and strip away some insulation.


Use a multi-meter to determine which wire belongs to which blade of the plug. (This is a great tutorial if you are unfamiliar with a multimeter)

When looking at a receptacle with the ground lug on the bottom, the hot blade is on the right (and is typically the smaller of the two). On the receptacle, this corresponds to the brass colored screw.


Insert the power cord into the box and secure the box connector with the provided screws.


Most dimmers will have a large aluminum plate that will not fit into the faceplate with out some trimming. A hack saw works great but sheet metal nippers are much faster.


Clean up any rough edges with a file.


Connect the wiring according to the diagram below:




Fasten the receptacle and dimmer to the faceplate using the provided hardware. You may need to snap the corners off the receptacle. Use pliers to bend at the score lines.



Finally plug in the unit and test using a multi-meter to verify wiring is correct. Mark voltage intervals to easily achieve repetitive results.