Automatic Split-Damper temperature control

[packplantpath]

Doc: I'm almost positive a flux capacitor would greatly aid in this endeavor.

Marty: But Doc, this is the 21st century, they don't have flux capacitors yet. Even if we could find a flux capacitor, where we gonna get 1.21 Jigawats of electricity.

Doc: My boy, we smoke in thunderstorms.

Looks good man.

What are the odds that the fan melts? I'm not sure where you are mounting it so that may be a non-issue.

 

[geek with fire]

That's the $58.38 question at this point. But the odds are high that something gets crispy. I just hope it's not my $25 servo controllers or my servos. I'm going to put one of the temperature probes in the fan box when I'm testing, to monitor for this.

Made progress on the box last night. I got the servo and the damper mounted in the box. I just need to cut the holes in the box for the damper to breath and make a mount on the tube to connect to the firebox, and I will be ready for a test. Getting closer.

 

[virgo53]

regarding the pix above, what model number and make of controlller, and where do you get those kinds of toys?

That level of control is highly interesting to me
Virgo53

 

[geek with fire]

It's all custom built stuff using hardware intended for robotics projects. I'm doing the programming using VisualBasic.NET

 

[ajthepoolman]

"Did you ever know that your my heeeeerrrooooooo!!!!"

Now slap a SQL2005 database on the backend that will insert the various temperatures and the outside weather conditions so that in a couple years time, the program can compare the current weather and temps to what was recorded in the database and make it's own corrections!

Who would of thunk that Artificial Intellegence would emerge from the SMF!

 

[richtee]

Heh.. I consider mine artificial sometimes ;{)

 

[fatback joe]

The way this thread has turned reminded me of an email I got a few years ago and saved because it always made me laugh.

Here it is.


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Please do not reply directly back to this email as it will only be bounced back to you.

 

[packplantpath]

Geez, I just relinquished my patent on one of those because I thought no one was interested.

 

[geek with fire]

OK, it's late so this might be choppy. I have the protype rig with the fan mostly built and gave a test run on the computer, so I thought I'd take some pictures.

Here's the basic unit: a sealed enclosure will hold the fan, the damper, and the servo that controls the damper. The electronics will be mounted outside the box incase it gets hot in there (won't know until I test on the smoker).....yes, the tube is a paint can....it's a protoype, not the floor model.

Here are 2 shots inside the box. I chose a plastic box only because it's easier to work with and cheaper than a metal enclosure. I have a bad feeling that it's going to melt, but we'll have to see.

The open end of the paint can will mount over the stock opening of the firebox. Most likely will add some fireplace gasket to keep contact heat from getting the can hot. It will also help seal the unit to the firebox.

We'll see this weekend how it runs!

 

[wavector]

http://cgi.ebay.com/P-N-TYP8105G-80X...QQcmdZViewItem

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Or, something along these lines. I'm concerned about the NEMA 3R box melting. I would consider, with this prototype, not mounting it directly to the firebox. Maybe go with flexible aluminum dryer venting material that is found at Lowes or Home Depot. I wish I was there to help you.

 

[smokebuzz]

I think it will be fine, kinda self cooling.

How are sensing position,? i think i only seen 3 wires.
Does that acuator have internal limits?

I like it

 

[bubba t]

...I would have to agree with Buzz on the self-cooling-- the fan intake air will keep things under control...if you did find the 'guts' were getting too hot from the nearby firebox you could install a simple metal shield on the back of the fan housing facing the firebox leaving a small air gap ...say 1" +/-... to help insulate.
What safety do you have in mind to protect/shut off fan when actuator closes dampner completely?..
I think your project is sweet!!...

 

[geek with fire]

Not sure I understand your question, Buzz, but the temperature measurement is done with a Type-K thermocouple mounted in the pit. The current temperature is bounced off of a PID loop which calculates what percentage of the damper and fan need to be open at any given time to maintain the desired the temperature.


I'm going to mount an oven probe in the box while running just to keep an eye on things. I think I will be able to catch a problem before it causes any damage.

As far as safety for the fan, check the program interface from the first of this thread. The program will maintain the positions of both the fan and the damper. If the program sends a signal for 0% airflow, the damper will close and the fan will shut off.

 

[smokebuzz]

How does the controler know where the damper/vent is positioned?

 

[geek with fire]

Servos are closed loop systems, meaning, you send them a signal of where they are supposed to be, and they move until they hit that point; and they maintain it. In the setup of my program, I simply state the position of fully open and fully closed. From there, I send the servo a percentage that I want it set to, and it goes there.

Same concept on the fan. I tell it what percentage of usage to run at and it tries to maintain that. The difference is that the fan is not a servo, so the program has no idea if the fan is doing what is told. Now, I can fix that by mounting an encoder on the fan that tells the program what RPMs it is running at, and make corrections if needed. However, and this is hard for me to admid, I think that would be overkill at this point.

 

[smokebuzz]

Would'nt a TACH be more appropiate for the fan?
My experiance with servo motors is, i always needed a encoder/resolveror some type of position feed back, otherwise i was always have to recalibrate and take into consideration of drag on my moveing components.
With no position feed back, would you be positioning on time of movement fwd/rev?

 

[geek with fire]

Well, I'm trying to recover from pneumonia, so I haven't been allowed to go outside to smoke anything. I tried to explain to my wife that the smoke would be good for my lungs.....yea, she didn't buy it either.

Anyhow, I've been spending time down in the "bat cave" and got the prototype completely wired up. Today, I got it mounted to the smoker. Anyhow, I snapped some shots just in case I melt the crap out of it tomorrow.

The black box below the fan box houses all of the electronics: I/O Card, 2 servo controllers, and speed controller. It looks a little bulky, mounts pretty solid.

Here's the inside of the firebox. The rig mounts to the hole in the stock pivot.

 

[bubba t]

..I was wondering how progress was coming on this sweet project!!... Hate to hear you been ill...Get better man....

 

[geek with fire]

Well, I'm still coughin' up large chunks of lung (yea, that was a bit too much information on a cooking forum!). And, the wind chill today would cause snot-cicles, so I gave up on testing the new temperature control setup this weekend. As soon as I feel better and/or the temperature gets a bit more reasonable, I'll give it a shot, take some pictures, and post some data.

Peace out (that would cause my wife to roll her eyes.....I never could pull off the whole "peace out" thing)