Affordable hot plate with PID regulator

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MicroBob
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Affordable hot plate with PID regulator

#1 Post by MicroBob » Thu Sep 26, 2019 6:57 pm

Hi together,
I recently bought this hot plate:https://www.ebay.de/itm/LCD-Bildschirm- ... 1913055912
I had it running for some days to cure Euparal on top of some blood smears we made on our meeting on saturday and so far it works very well.
The heater is just switched on and off, but the interval is regulated finely so that the temperatur is very constant. It is a real PID regulator and if I could understand the chinese manual I could even dive into the menu and change settings. fortunately this is not necessary at all.
These things are sold for smartphone repair which makes them affordable due to the numbers made. I paid 28,90€ incl. shipping for it.
It is said to go up to 350 or 400°C but I wouldn't trust it so far. I case you buy one: I would suggest to keep an eye on it for the first hours and put it on a temperatur resistant surface.

The clamps don't have to be mounted to the plate, they come in a separate bag.

Bob

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Crater Eddie
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Re: Affordable hot plate with PID regulator

#2 Post by Crater Eddie » Fri Sep 27, 2019 1:02 pm

Looks like a good purchase. Those PID devices are great. I used a cheap PID from Amazon (about $40 USD) to replace the trashed controls on an industrial oven we bought at scrap value at work, it works great, after warm-up it holds the oven temp to within 1°F. Used another one to build another oven, same great results. I have only had to tweak the settings on one just a tiny bit, the other not at all. I'm thinking about buying one for myself to upgrade my electric meat smoker at home.
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mrsonchus
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Re: Affordable hot plate with PID regulator

#3 Post by mrsonchus » Fri Sep 27, 2019 1:31 pm

Aha! I just looked-up 'PID device controller' and it seems I have used one to control my wax-ifiltration oven (actually a mini-oven for apartment use I believe)....

Here is one used to control temperature of my 'wax oven', it's sensor simply sits inside the oven next to the wax-pots....

ws_700x525_into_oven_1.jpg
ws_700x525_into_oven_1.jpg (92.48 KiB) Viewed 299 times
As said, it's very good indeed and gives a nice flat max-min response about the set temperature.
John B

MicroBob
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Re: Affordable hot plate with PID regulator

#4 Post by MicroBob » Fri Sep 27, 2019 2:33 pm

Hi John,
it is not a difficult task to regulate a hot plate so a PID reulator is a bit overkill for this application. But: I have a similar looking regulator like yours for a small hot plate I built myself. My one has a very simple regulation scheme and the temperature varies +/- 2°C. Not unusable but not as convincing as the big hot plate I showed here.
The big hot plate could also carry a hood to be used as an oven or drying cabinet. What I don't like about it is the 800W heating element. If something goes wrong this hot plate will become really hot! :shock: It would be a good idea to inclue a safety circuit that cuts of a a certain temperature like 150°C.

Bob

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mrsonchus
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Re: Affordable hot plate with PID regulator

#5 Post by mrsonchus » Fri Sep 27, 2019 2:46 pm

Hi Bob - yes I agree, the controller of the oven is my safety-net. Set above the temperature of the PID, it will 'catch' an out-of-control PID and turn-off the oven in it's own way. Very handy to know that the second control is there.
This set-up really works well as the sensor has a robust metal cylindrical 'bar' (only about the size of half a matchstick) at it's end and is able to be leaft actually in liquid wax during operation.
John B

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