Hotplate

DIY Hotplate

WARNING!!! This project uses high-voltage mains electricity. Excercise extreme caution if you plan to carry out this project on your own. Mains voltage can kill

A hotplate is a useful device to have in any workshop, it can be used to solder and de-solder SMD boards quickly, heat liquids, solder over large areas that a hand-held iron just wont cope with, or simply to keep your coffee warm on those late-night projects.

My primary concern about this project was whether the iron could reach sufficient temperature to be of any use (particularly melting solder), however a proof-of-concept test revealed that it could both exceed the required temperature, but also maintained this temperature for quite a while after power-off.

Parts

The main component of this project is an old clothes iron. The best type to get is a non-steam iron, as these have a completely flat base without holes (where the steam would come out). I acquired one of these from my mum, who had one laying around in the back of her cupboard underneath some sex-toys, but you could probably pick one up from a car-boot sale or yard sale for a few pence).

Next you need a base to mount the plate on. since a clothes iron is designed to be hot-plate down, you will need to mount it upside-down on some heat-resistant material. For this particular iron I was able to use a part of the iron itself.

Control circuit. I'll be coming to this a bit later, but the idea is to maintain the hotplate within a narrow range of a pre-set temperature.

Proof of concept

The initial proof of concept model was quickly thrown together with little safe-guard for safety or control. The 1000w heating element it wired directly to a plug, the only control is the switch at the plug socket. Initial testing of the plate was carried out by placing a piece of solder on the plate, and the plate was switched on. The solder melted after about 30 seconds, and the power was switched off. At this point I placed a spare SMD board on top of the hotplate, and within a few seconds was able to remove all the components neatly.

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