PID Controller

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ajwillsnet
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Post by ajwillsnet » Thu Jan 05, 2012 23:28

When I poach things in my waterbath, I first of all place the items (sausage) in a vacuum sealed contained. I use an old turkey roaster that I pickup up for $ 20.00. I fill the roaster half full with weater and controll the water temperature with a PID controller. Very accurate controll to within .1 degrees . Also when I use my water bath, I put a small acquarium circulating pump into the water. This helps stabilize the temp.
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Post by ssorllih » Thu Jan 05, 2012 23:46

What is a "PID controller"?
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Post by ajwillsnet » Thu Jan 05, 2012 23:56

Here is the definition of a PID controller: A proportional-integral-derivative controller (PID controller) is a generic control loop feedback mechanism (controller) widely used in industrial control systems - a PID is the most commonly used feedback controller. A PID controller calculates an "error" value as the difference between a measured process variable and a desired setpoint. The controller attempts to minimize the error by adjusting the process control inputs.
You can pick them up on EBAY for about $ 40.00 c/w solid state relay and a temp. probe. These are used in place of a mechanical thermostat which has a relatively poor control of what you are heating, be it a smoke house or a water bath. You do need to do some wiring and put the controller and SSR into a project box but its worth the effort.
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Post by ssorllih » Fri Jan 06, 2012 00:01

Good . Now your diagram doesn't shown how you establish a set point.
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ajwillsnet
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Post by ajwillsnet » Fri Jan 06, 2012 00:42

In the picture below, you will see a picture of the front of my controller. It is marked SESTOS.
There is a keypad on the front of this to allow the user to establish a setpoint: https://lh4.googleusercontent.com/-Hg0u ... 280171.JPG
You momentarily press the button on the lower right side. When it flashes, you run the display in the set value window to the temp. you want to maintain. Then press set. You start up your smoker or water bath and insert the temp. probe and let the PID do its job.
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sketch of pid controller

Post by ajwillsnet » Fri Jan 06, 2012 01:02

Here is a pencil sketch of the controller I have built: https://picasaweb.google.com/lh/photo/8 ... directlink
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Post by ssorllih » Fri Jan 06, 2012 01:36

I would love to see a circuit diagram. I am an electronics technician with an understanding of circuit and systems. I could show the timer and temperature controls on my kitchen range but it wouldn't give anyone the circuits to duplicate it.
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Post by ajwillsnet » Fri Jan 06, 2012 01:46

I posted a circuit diagram/sketch at 16:02.
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Post by ssorllih » Fri Jan 06, 2012 01:58

That was worthless.
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Post by ajwillsnet » Fri Jan 06, 2012 03:43

I guess that you are not as technically inclined as you say you are! That sketch would provide all the information to turn a PID module into a very accurate smoke house temperature control.
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Post by ssorllih » Fri Jan 06, 2012 04:08

If your smoke house was electrically heated and if you choose the right thermocouple and your heaters were sized to the controller. None of which you offered detail concerning.
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Post by ssorllih » Sat Jan 07, 2012 21:08

I understand how they work now and assembly would be simple but I can't figure out how to apply them to a LPG heated smokehouse except to have a pilot light and a solenoid to turn the gas burner on and off.
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Post by Maz » Sun Jan 08, 2012 05:02

I can't figure out how to apply them to a LPG heated smokehouse except to have a pilot light and a solenoid to turn the gas burner on and off.
That is exactly what I have a pilot flame with a solinoid to turn the LPG on and off. If you are using an electric plate or element it is a good idea to switch an external relay instead of putting the load on the contacts of the controller. :grin:
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Post by ssorllih » Sun Jan 08, 2012 05:14

perhaps I will try it. I just canablized my old kitchen range, took all of the valves and burners and the oven control with the thermostat. I just have to adjust the orifices to work with LPG. I have a solar panel and a small 12 volt battery and some 12 volt relays. Now to find some 12 volt solenoid valves.
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Post by Gringo Loco » Sun Jan 08, 2012 06:02

I just got my PID put together today, thanks to a lot of help and advice from ajwillsnet, and I hooked it up to a hot plate with a large pan of water and the tempature stayed with in .01 of a degree. My current temp controler on my smoker will fluctuate about 8 to 10 degrees from the time the electric burner turns on then turns off. I can't wait to put my PID controller on my smoker.
This is going to be a great investment, less than $100.00, and a good addition to my smoker.
Thanks again Bert,
GL :grin:
Ponsa llena, Corazon Muy Contento!!
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