Since this is mains wiring, we should be very careful: make sure everything is unplugged when working on it!įirst of all, we should ground the hotplate to prevent electrocution if anything goes wrong. It is a good idea to test the system at this point before going any further. The Arduino is powered via the mini USB port, so we connect it via a USB cable to the power brick. The MAX6675 was taped to the back with some double sided tape. I mounted everything to a small piece of perfboard, soldered to the back of the LCD screen. Since they don't draw a lot of power, we can simply connect everything to the Arduino pins and configuring the required pins for power and ground.ĭue to some space limitations, it didn't turn out as neatly as I had hoped. It then displays the temperature on an LCD and switches a Solid State Relay (SSR) if needed. ![]() The Arduino gets the temperature from a thermocouple, whose signal is amplified by the MAX6675. The electronics part of this project is quite straightforward, we only need to connect some modules together. Just keep the warning above in mind when tuning the design for your own hotplate. I added the Fusion 360 file so that you can adjust it to your needs. Furthermore, the temperature is only high during a few minutes, so the legs can never reach the same temperature as the top (steady-state is never reached). Since air is a very good insulator, the MDF doesn't heat up at all, let alone catch fire. Everywhere else, the MDF and hotplate are separated by a small air gap. The MDF parts only touch the feet of the hotplate, which are significantly cooler (max 60☌) than the top of the hotplate. In general it isn't, but I have made the case such that this is not a danger. Something to be aware of: you might be wondering if using MDF in combination with a 250☌ cooking plate is a good idea. I used a small tin strip, but you could also use tape or a zip tie (drill 2 holes next to the thermocouple hole and feed the zip tie though them). Next, it should be pressed against the MDF. Drill a hole and feed the thermocouple through. ![]() The thermocouple should be firmly pressed against the hot plate. The LCD can then be screwed in place, together with the button. ![]() you have laying around can be made to fit. Some additional holes need to be drilled: one for the power cord, one for the button and two for the LCD. Add the hot plate and secure it in place (mine is secured with screws in the bottom). The pieces can be glued together as a puzzle, just use enough clamps. Due to the living hinge, this design can only be made on a lasercutter: small slits in the MDF make it able to bend. In my case however, there was not enough room, so I had to design a new one. A first option is to modify the existing enclosure, this is viable if it is big enough to accommodate a SSR, LCD etc. For the case we have two options, depending on your hotplate.
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