Adding PID controller

Discussion in 'Smoker Builds' started by macbillybob, Apr 1, 2010.

  1. Here is the start of my PID controller. Only thing missing is the controller, thermocouple and relay (ordered from but not yet delivered) Saw where the relay can get hot so I ordered it with a heat sink and decided to put in a small fan.( I have tons of computer "junk" laying around.) Will use this to control a 1250 w element. Fun little project so far, assuming nothing burns down. I went with 12 ga wire except for the plug coming in, it is 14 ga. I realize this is probably the weak link but shouldn't come close to pulling 15 amps.

    Fan and little green light work. So far so good.

    Plan is for the green light to be power on (it works) and the red light to be when the element circuit is on.
  2. smokednarwhal

    smokednarwhal Meat Mopper

    Looking good, I enjoy seeing different implementations of these DIY boxes. Pretty clever use of the 12v converter and a receptacle inside the box to run the computer fan. I look forward to seeing the finished project.
  3. Thanks, I used your implementation and others I had seen as motivation, except I decided to build my own box from scraps and save the bucks. Gave me the extra room for the plug, fan etc.

    Wonder how I am going to make the top out of an LCD TV? Do I need a hard drive also?
    Sorry I got distracted.[​IMG]
  4. Got all the pieces parts today. Installed and it works! Got to get up to speed on the config. Are you folks who use this PID having any issues with it cycling too much?
    The element is pulling just below 10 amp.
    Will be experimenting this weekend.
  5. roksmith

    roksmith Meat Mopper OTBS Member how did it work?
    I just got my new PID controller in the mail yesterday and plan on using it to control my draft induction fan on a new vertical smoker I'm building. Shouldn't be so many components since I'm just running a 1A fan and should be able to power it right thru the relay output on the PID.
  6. morkdach

    morkdach Master of the Pit OTBS Member

    looks good i like the way you did the control box.
    they do work great. i have used mine about 25 times since the build.[​IMG]
  7. roklimo

    roklimo Smoke Blower

    Usually reducing the Gain, (or increasing Proportional band) will "slow down" the control, and cycle less. Each PID manufacturer chooses which units it uses for tuning the controller.
  8. I finally figured out how to set the controller up for on/off control only. (not that it is that hard but I am a little slow sometimes)

    I set At=0
    set Hy=3 (3 degrees either side of your set temp will activate/deactivate the relay)

    This is a 6 degree swing and that is ok with me. Keeps the cycling of the element down. I haven't tried lowering the Hy to 1 or 2. Just figured that would cycle more and I am not sure that is getting me anything.
  9. where inside your smokers are you placing the temp probe (the one that is connected to your PID) ? Any help on this would be appreciated as I'm in the fridge conversion build myself. Thanks!!!
  10. My probe is on the same level as the meat. In the back of the smoke house. My house is small so there is not much temp fluctuation, unless you are right over the heating element.
  11. Much appreciated for that answer and I like to looks of your smoker! Thanks again!

  12. mgnorcal

    mgnorcal Meat Mopper SMF Premier Member

    A general question:

    Does the PID work better for smoking meat than either an ordinary oven thermostat or even a range-burner infinite switch (where the operator occasionally checks the temp and adjusts the knob)?

    I see lots of people here talking about PID's and I'm curious about what advantages they offer.
  13. Don't have any experience with the thermostat etc., maybe someone else will give their 2 cents worth. The PID seems to give a very precise temperature control. I don't know if the others do.
  14. roksmith

    roksmith Meat Mopper OTBS Member

    Haven't got mine installed yet, but the reason I went with one was that they are supposed to be a little more "intelligent" than a normal temp switch. At least in my case, I am using the PID to control a draft fan to control heat. A typical temp switch will kick on the fan until the cooker comes up to temp and the kick off. Typically the heat will continue to rise above the selected temperature some amount then drop down to the preset temp then kick on again which will cause a thermal roller coaster. The PIDS are supposed to "learn" and actually become a bit predictive cutting off early knowing that temp will continue to rise thus being more accurate and although a thermal roller coaster is going to happen regardless to some extent, a PID is highly tunable and can provide much more stable control.

    At least that's the theory.. We'll see in a couple weeks :)
  15. dick foster

    dick foster Smoking Fanatic

    I picked up a nice little PID from a site in China for cheap, at about 35 bucks.

    I use mine to control a small draft fan, a 32 CFM, 110VAC muffin fan that I had in my junk box, so I used a small SSR that I already had in my junk box too but they sell SSRs for cheap too if you need one of those for your setup.

    The PID takes just about anything for power no matter where you are, either AC or DC as a matter of fact. It has an output for controlling a SSR (Solid State Relay), about 10 volts DC. The SSR which is used to control the temperature control device whether it's a fan or a heater element. I has a separate relay output for an alarm which can be programmed as either an over or under temp alarm. I use a red light bulb as an under temp alarm to warn me if my temp is getting too low and I need to add some fuel.

    It has a self tuning feature if you need to use the PID type control and don't feel up to PID programming. I've set mine up for simple on-off control as I am only using it to control a stoker fan to control the lump/chunk fire I use for smoking.

    The bottom line is that it's cheap, small and versatile.


    I got this temp sensor from the same outfit which is a platinum type instead of a regular K type thermocouple. It has a stainless steel housing. For 5 bucks, why not? It actually uses a thin film on ceramic substrate sensing element using platinum as the temp sensor. I drilled a hole in the smoke chamber and mounted it in the smoker so it sets just below the level of the grill. I usually cover is with a piece of aluminum foil to keep it from getting all greasy from drippings.

    Temp Sensor

    This SSR should do the job for just about anything, even the heating elements for you electric smoker fans out there. It will handle up to 40A at 220VAC which is more than any of you probably run in a smoker. That's 8.8KW or almost 9 thousand watts, folks. Another 5 bucks or so.

    If anyone needs help with how to wire one up, let me know. I'd be happy to give you some pointers. I'm a retired EE type. The instructions can be confusing to some because of the poorly written documentation but I can help out there too if need be. Not griping their English is much better than my Chinese.

    So far so good. It keeps the temp just where it needs to be and just right. I have it set for a 3 degree swing but can be either tighter or wider as you may want.
  16. smokinajs

    smokinajs Newbie

    Hello. I am considering purchasing the setup below to run a draft fan like what you have.. I am new to the PID stuf and it looks simple enough but I still have a few quesitons

    1. What kind of power hookups are you using to power up your PID. I need to see who you set that part up. Type, brand and picture would be great.

    2. How are you connecting the fan to the PID.

    3. As far as the themocoupler, are you having it wired directly into the PID and if so, how is that done.

    Thanks sorry for all of the questions but I really want to build one of these and need to know the above to complete project.

    Buster Davis

Share This Page