Kind of cooktop

Hi,

So I planned to create an alloy(?) hotplate, with resistors heating the thing up and controlled by my arduino to adjust/stop it automatically to keep food warm how I like (35°C max).

My problem is that I don't know what parts I will need to heat the hotplate and the best way to connect them; and if there are off the shelf resistors I can buy to achieve that goal.

I could reuse an existing hotplate but I am interested in something I can make myself from the ground up. Pride and stuffs.

Please, do not hesitate to ask if I didn't make a point clear.

Thanks!

How are you going to power the hotplate?

If it uses mains electricity then I would use a standard product for safety reasons.

...R

One doesn't normally do this with "resistors". One does this with "resistance wire". It can be purchased made from various alloys, each with their own positive/negative properties. It can also be purchased in a myriad of different resistance values for a given length. I bought a whole role of it for a Project I had. Obviously, there are safety concerns because a good number of watts is involved. But, it can be done if one is willing to take the precautions and risks. You will Need something to measure the temp of the plate, a way of turning the power on/off or maybe even PWM it. You should also put in a safety device that cuts the power if a preset temperature is exceeded. Don't rely just on the Arduino turning the power off... what if the program stops running with the power on? That's why you Need a separate thermal safety device. Whatever the device costs, it's less than the value of the house.

Keeping food hot at 35°C for a considerable time is a health hazard.

You need to keep the food cold, so that bacteria don't breed quickly, or hot enough to kill them.

The temperature that you are suggesting is right in the danger zone.

@JaBa: thanks! resistance wire is the missing term. From then on, I can work out the rest

@JohnLincoln: you are right, but the project aims at keeping my bread at the temperature I love it to be for a short period of time (few minutes) just before breakfast. I don’t think I should worry about anything in that context. I hope!!

Run the enclosure at a temperature above the danger zone, for example 70 deg C, and use a timer to switch off the heater when you think the bread will be warm enough.

If you forget to set the timer, or if the timer fails to switch off the heater, the food will gently cook at a safe 70 deg C. It'll be a little dry but it wont kill you, or be hot enough to catch fire.