ATT: Builders of a PID Temperature Controller

[beanflip]

In the near future I am wanting to build a PID temperature controller and have some questions.

1. Should I buy a PID with 1 alarm or 2 alarm.... and whats the need for the alarm?

2. Should I use heatsinks or a fan to keep the components cool?

3. Is the lenght of the type K thermocouple probe need to be 6"?

4 . What project enclosure box is better to use plastic,aluminum or maybe a clear box?

5. Need help with the wiring or diagrams ( 1 or 2 are really good in all the reading I have done)

6. Would any of you builders that built a single PID build a dual PID temperature controller instead and why?

7. Is there any thing that any of you builders of the PID temperature controllers would change what you have already built if so what?

I dont want to be one of those ..... would of --could of --should of -- kind of dummys.

If I missed any thing good or bad I m all ears.

You can pm me if you dont want post here.

Thanks Jim

[cheese1566]

I built my units out of scrap parts i had around and the PID's and Thermo's came from a benefit here a couple years ago.
The PIDs I have are a little different then the Auber Instruments, but the same in function. I have them set to activate a light when near the temp setting, but I seldom look at it as my eyes go right for the digital temp readout.

One box is in a plastic case, but is a low voltage unit for my lube heaters so no SSR relay is used.
The other one for my pot is in a metal box that was once a computer power supply box. That one has the SSR mounted on the inside of the metal housing for cooling.
The probe I use for each is removeable so i can move it from pot to pot and from luber to luber.

Wiring is easy and there are some pretty good guides and schematics in the threads.

Have fun!

[OuchHot!]

I do not use the alarm but if you wanted, you could set an under-temp to buzz. That would tell you the thermocouple fell out of the pot or broke. It would likely drive you nuts during warm-up. I just look at the digital. I have had no problem with overheating without fans. I would use a metal box as the inevitable lead splashes weld themselves to a plastic box and look poor. I would build a double pid because I want to control a hot-plate at the same time. Aluminum and brass molds can be warped if you use a hot-plate set too high. A six inch thermocouple should reach the bottom of any usual furnace but shorter can be used...it must be covered in alloy in use. I need to modify my pid with sort of a visor over the readout. This would keep most lead splashes away and make it a little easier to read in direct sun.

[Walter Laich]

I used the Auber PID and their small box. I had to mount the SSR on the outside on the back of the box--it's really small in there. I also modified the clamp around the PID so I could mount it 90* from how it fits normally.

Didn't use the alarm function

I didn't put a connector in my K thermocouple and still feel that's OK in my usage of it.

Here is a page I made about my build: http://home.comcast.net/~walterlaich/pid.htm

[ChuckS1]

I used the Auber components, but didn't use their project box (way too expensive for me). Here's what I would recommend. Either go to a local computer store (not Best Buy, but a local mom and pop store) and ask for a blown power supply. I got mine that I used for my prototype for $3. I took it apart and used the steel enclosure.

Alternatively, here's a link for the enclosure I used for the final enclosure. You don't need aluminum because we're not dealing with any real degree of heat output and aluminum boxes are just too expensive. Steel is perfect for this. Plastic is okay too, but personally I prefer metal. Jameco Electronics has lots of boxes to pick from that will work. I would suggest you not go smaller than the one in the link below.

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_208911_-1

Oh yeah, and don't waste the money on the heat sink. The SSR doesn't generate enough heat to worry about it. Like one poster said, mount the SSR on the metal box and the box will be your heatsink. I scraped the paint off the box to bare metal and the put a heat sink compound I had from my last computer build on it and then screwed the SSR to the box. The key here is bare metal (SSR) to bare metal (enclosure) contact. The heat sink compound was overkill and really not needed, but you should get good contact between the SSR and the enclosure.

Get the 6" probe.

I used the the thermocouple connector but unless you like messing with teeny screws and thin wire, I'd just go with the probe. It's much easier to connect to the PID.

I also added an AC receptacle so that I could plug in my pot to the back of the PID enclosure. This is what I used:

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2114095_-1

I also added a male receptacle to the back so the I could use an old computer power supply cable. Really not needed, but what the heck, I ha the Dremel and soldering iron out. Link:

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_16652_-1

Lastly, I added a simple on/off rocker switch like this one to turn the PID on and off when it was plugged in:

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_316022_-1

If you use an old computer power supply enclosure, the male receptacle and on/off switch will already be there.

[theperfessor]

My write up of my dual PID is a sticky on this page. I have had no problems with mine. I would include an on/off switch for each unit but other than that I don't think I'd do much else differently.