HeaterMeter V4.3 kit with Thermocouple


 

Arlo Poa

New member
I will be building my own HeaterMeter V4.3 kit and would like to use thermocouples. I will be buying the V4.3 kit with thermocouple and will buy the blower, SD card, Raspberry pi, and power supply on my own. What does it mean when the Product Description says "Surface mount components needed for thermocouple support (AD8495) for pit probe already soldered and tested"?

Also, what is the physical difference between the "no thermocouple" kit and the "thermocouple" kit? And I believe the cases are slightly different?
 
The only difference between the thermocouple and non-thermocouple kits are that the thermocouple version has the amplifier circuit pre-installed on it. See the photo on the PCB page where it has the little components installed in the bottom right corner. It also includes the thermocouple minijack instead of a fourth thermistor jack.

Physically, that's the only difference. The thermistor version has 4 round thermistor jacks along the input edge, the thermocouple has 3 round thermistor jacks and one rectangular thermocouple jack to replace one of the round ones.
 
JKalchik, I'm new to Heatermeter so I thought 2 thermocouples and 2 thermisters would be a good setup. I intend to only run two probes at a time. It sounds like with the thermocouple version w/ V4.3 kit I can only run 1 thermocouple.
 
IIRC, the kits that Bryan sells are either 3 thermistors and 1 thermocouple, or all thermistors. I haven't looked at the 4.3 PCB layouts, but in older versions, I thought that he only had the layouts for a single thermocouple amplifier setup. I'm pretty sure the software will handle it, but you'd have to modify the layout as well as solder up the surface mount components (not for the faint of heart.) There's a few folks here who certainly should correct me where I'm wrong.
 
Thank you Steve_M. I'm thinking it may not be worth the extra cost and effort to incorporate thermocouples for now. Overall, it seems thermocouples are the better choice but I'll consider adding them in the future for V4.3. If I'm going to buy thermocouple probes I don't see the use of having just 1 thermocouple probe and the remaining probes thermistors.

Does anyone know if having 1 thermocouple out of 4 ports is useful versus using all thermocouples?
 
Thermistor probes are great, but they tend to fail under high heat (500+F). This is what drove the decision to make an optional TC probe for the pit, as TCs are able to withstand high heat and they're also rugged and affordable. The only downside is that each TC probe needs it's own TC amp circuit, whereas the Thermistor probes have a much simpler signal path into the micro controller.
 
Steve_M, your explanation was very helpful...now I understand the reason for 1 thermocouple. I've always used dome but didn't think about monitoring pit temperature (pit temperature is grate temperature for indirect heat, correct?). I think I will go with the TC for my HeaterMeter V4.3. Thanks again.
 
I've had no issues with 1 TC and 3 Thermistors. the 3 thermistors are for the food, so they never see the high heat of the pit (unless you like your food VERY WELL DONE). The TC stays on the grate, and the thermistors stay in the food.
 
I have a Delta 50mm fan which has a square air outlet. I'll be drilling a 1-1/2" hole to slide an electrical conduit pipe into the bottom of the pit for the fan to get air to bottom of pit. Does anyone have ideas on how to transition from square to a circle adapter?
 

 

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