Pid temperature control

[Dano41]

Hello I am working on a project were I need to heat a small stainless cup up to 185c and keep it at that temperature, as far as I kown I need a Pid to do this.Once set I don't have to adjust it again,any pids Ive seen on line have digital read outs which I don't need.Could anyone on hear please help or tell me were I could buy one?Attached is a pic of the unit in the origional.

[David]

Temperature controllers is a very wide subject, and your post does not really give enough information for the replies to be particularly specific. As a general rule, Google is your first port of call if you want to buy one ready made.

[Dano41]

Hi David,thank you very much for taking the time to reply.I have tried Google but can't get exactly what I am looking for.What I need is a setup similar to the one in the pictures but which is as small as possible.The pid heat controller will run from 240 volts the brass band heater is 250 watt and surrounds a stainless steel cup which I want to keep at a temperature of 185c.This is a device for sublimating oxalic acid for the control of varroa mites in honey bees.Any help would be greatly appreciated.

[piratepaul]

Maybe just some sort of thermostat, a bimetal and a thermometer... How accurate does it need to be?

Tar&stuff.

[Dano41]

Hi piratepaul thank you for reply.It needs to be kept at the 185c very accurately.In the pics it is a pid controller I'm told.Do you know were I could buy this type of unit ready made?I have bought a digital pid and a ssr but they are too bulky to fit in the handle plus the fact that once I set the temperature I don't have to change it again so the digital display isn't needed.What I need is the smallest pid controller which the mains can be attached too which I can set the temperature once and it will keep it at that constantly.

[piratepaul]

I don't know where to buy one.
Maybe you could repair the old one.

If you look at the board you see a PCB track burned out, it appears to be on the power supply side, not the micro controller side. I suspect the blue relay is stuck on, maybe you need to replace the relay and repair the track.

If you can photo the PCB on both sides and keep them straight, put the two photos up side by side so I can get an idea of alignment, I/we can perhaps tell you how to repair it.

Can you use a multi meter, do you understand Ohms law?

I don't have much time just now, I have this weekend off work but am working nights and doing a lot of overtime until mid January, but will be back at some point.

Tar&stuff.

[Dano41]

Unfortunately that is not my unit I got a friend to take the pics of the inside of his.

[piratepaul]

If you look at the top pic there is an L shaped hole in the board, there is orange wire behind the hole, the wire is a similar colour to burned copper, I thought it was a burned PCB track in the area of the relay, on second inspection it is obviously a hole... My mistake.

Still may be I/we can repair the old one.

What is wrong with it, does it get too hot/not hot enough/not come on/not switch off etc...what?

Tar&stuff.

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[Dano41]

That board which is in the pictures is inside a friends unit which is fully working I was hoping to make a similar one if I could get the ready made circuit board.He is a pic of the device fully assembled.

[piratepaul]

Right so you don't have an old one which is broken, I have the complete wrong end of the stick here...

As far as I can see the PID is a device which switches the heater on and off according to a programme, it senses past history to tell it how often to switch the heater on, giving a smoother heat than a simple thermostat ( googled it ) errrrr.
What's wrong with a baly thermostat.

Are there any numbers on your friends device?

I don't know really, I think I will just but out of this thread, don't know...pass.

Tar&stuff.