Most soldering irons are either on or off; it would be much more useful if you were able to change the temperature of the iron. So I designed a simple control circuit that will let you adjust the output of a heating element.
Find more at the Maker Shed: https://makershed.com
Make: Electronics, 3rd Edition: https://www.makershed.com/products/make-electronics-3rd-edition-pdf
Get the full project instructions: http://makezine.com/projects/adjustable-temperature-controller-heating-elements
