Webcontrol temperature sensors for a Smoker

[potts.mike]

Does anyone know of any temperature sensors, analog or 1-wire, that can withstand the temperatures of a smoker? The hottest that I can imagine things getting is maybe 350 F. Even better would be if they were food safe. I have thought about a thermocouple but i think these might need an amplifier and thats something I am not interested in.

 

[fwd03]

Oven sensor, which is heat senstive resistor, probably could stand smoker temperature. I have a GE oven, which allows to attach a food temp sensor to it inside the oven, to measure food temperature. Searching on eBay you will see a lot of them. You will probably need to have a resistor bridge, having this sensor as one part of the bridge, measure the bridge differences. This article may help you understand oven sensor:
http://www.appliance...en-sensor.shtml

 

[potts.mike]

I also found a person using detachable sensors from digital food thermometers.
Can anyone confirm that there is not a 1-wire sensor that is rated for these temps?

 

[CAI_Support]

One wire sensor inside must have microcontroller. Most microcontroller will not work well beyond 70C, Even military grade IC can not work beyond 125C or about 250F. They are blow your 350F requirement.

 

[potts.mike]

I think I'll attempt this with the meat thermometer probes.

 

[fwd03]

Please share with us your meat thermometer probe result. Do you need to connect that through Ross' terminal board with op amp?

 

[potts.mike]

I plan on getting some terminal boards but have never done anything with an op amp. I ordered some thermometers and dc-dc voltage converters to get things started. I'll need a relay to trigger the fan and a 12v power supply for everything.

 

[rossw]

I plan on getting some terminal boards but have never done anything with an op amp.

My terminal board has a quad opamp already layed out and connected. Since the WC board only has 3 A/D input channels available, only 3 of the opamps are connected, leaving one "spare" for other uses. I already published the circuit for one channel (all 4 are the same):

Depending on the sensor you use, it will probably have fairly small changes, the above circuit may be useful to amplify it to something more useful.
The "spare" opamp may assist you with some offset to give you a better span. Once you have the details for your sensor, if you post it here we may be able to make some suggestions as to what should work best.

 

[68sting]

Could you get data from an igrill? They work with apple stuff. It's over my head but you might be able to sniff data from a maverick some how also.

 

[JimS]

There is quite a lot of information on the web about DIY BBQ controllers that should help. A quick search didn't turn up any forums but I know they exist. Here is one link:

http://www.ice8420.com/blog/2012/01/diy-pid-control-for-bbq-sous-vide-mash-tun-whatever/

Some (like this one) use more off the shelf parts while others build more of the electronics from scratch.

Wondering why you say you don't want an amplifier. It sounds like you are willing to put together other circuitry...

 

[potts.mike]

It's not that I don't want an amp. I'm just not familiar with their operation. I ordered temp. Probes for an oven. I believe they are themisistors so I'll need to do some calibration to figure out the resistance for a given temp.

 

[rossw]

It's not that I don't want an amp. I'm just not familiar with their operation. I ordered temp. Probes for an oven. I believe they are themisistors so I'll need to do some calibration to figure out the resistance for a given temp.

Most "thermisters" will require a 3rd order polynomial to get reasonably good accuracy from them. I did some tricky code many years back for an atmel 90S8535 using only integer math that could probably be converted to something the WC could manage. You will need some specific information on the sensor itself though, and its characteristics, in order to calibrate it.

 

[potts.mike]

The plan is to use the oven for calibration. Once I have the correct curve fit I'll use the logic server in CQC to calculate a temp.