High Heat Cooking???


 
RalphTrimble said:
Well, I think its game over before it began....

As careful as I tried to be, I could barely hold the thing because it is so small. It slipped from my hand and I heard one bounce and my guess is I will never see that thing again. I will look, but I am not very hopeful....
Click to expand...

Doh! Maybe put a nylon stocking over the vacuum nozzle and see if you can suck it up into that?
 
IDK, damn thing was SMALL... I was trying to crimp on one lead and I could barely see the wires coming out of it and away it went.... the bounce is what scares me, I heard the "ting" then nothing, could be anywhere, including in a garbage can with lots of little scrap from 3D printing.... So it may just be GONE....
I will try to look some more after I cool down a bit...
 
Well, I tossed the room and as I expected I didnt come up with the thermistor. I pretty much knew it was gone when I heard the bounce, since I could hardly hold onto the thing because it was so small once it was out of my hand I knew it was history. I guess I should have stuck it to some tape first thing so I had something to hold onto and could see... Or perhaps it should have been delivered attached to tape like other small components. Longer leads would have been a real plus, since that was how I lost it, trying to spread apart the short (~3mm) leads so I could get the crimper in there. Reading the data sheet I understand why the leads are so short, I guess they are made of platinum so they can handle the heat.

I am still bummed out that I lost it, specially after waiting so long for it to be delivered. However, even if I had been able to get it connected, tested and working I think it is a bit small for the average guy to be working with (certainly too small for me! LOL), and the lack of leads length blew a lot of my mounting ideas out of the water, as I had planned to "fly" the thermistor by the leads about an inch before I connect the wire so the wire would be away from the heat a bit.

I may fill out the evaluation form and provide my feedback about the lead length and need for the unit to be delivered attached to something that can be seen with the naked eye and see what they say.... It looks like the approval for the part sample came locally but the thermistor actually shipped from Belgium, I guess that accounts for the delay and lack of availability in the USA....
 
Hey Ralph,

Whenever I drop something tiny on the floor and I can't find it, I will get on the floor and put my eye as close to the floor as possible. Then, I take a flashlight and aim it horizontally positioned near my eye and aiming toward the direction I am looking. Small things become large and easy to spot. You might give that a try.
 
Been there, done that..... and used the shop vac with some silk screen over the end... no dice....
The problem is it is VERY SMALL.... I have a suspicion that it jumped right into my garbage pail that is full of tiny scraps from 3D printing and TONS of small cat5 wire snips from a year of building cables, if it went in there its lost forever....
I will still keep my eye out for it, specially when moving things around, but I have officially stopped "looking" for it at this point...
 
Thinking about this some more, one could probably rig up something like a AD8495 analog thermocouple IC and have it pump into HeaterMeter. You wouldn't populate one of the pullup resistors on the HeaterMeter board, then run 3.3V/Signal/Ground to the chip and the source could easily be modified to read the 5mV/C reading put out. I'm not sure how good the quality of the output would be and it would disable using a thermistor as the pit probe though. Cost ~$5+thermocouple cost which is a whole lot better than $25 for that Vishay super-thermistor.
 
Bryan Mayland said:
Thinking about this some more, one could probably rig up something like a AD8495 analog thermocouple IC and have it pump into HeaterMeter. You wouldn't populate one of the pullup resistors on the HeaterMeter board, then run 3.3V/Signal/Ground to the chip and the source could easily be modified to read the 5mV/C reading put out. I'm not sure how good the quality of the output would be and it would disable using a thermistor as the pit probe though. Cost ~$5+thermocouple cost which is a whole lot better than $25 for that Vishay super-thermistor.
Click to expand...

IDK about making the change in a way that would eliminate the ability to use a standard probe for the pit probe, that might rock too many boats and force everyone to move in the thermocouple direction. Is there any way we could build an external thermocouple adapter that could have it's output converted to be able to plug into the standard probe jack? Or perhaps the spare pins on my CAT5 jack could be used to connect the external thermocouple adapter to the HM and then make the software so you could choose to use probe0 as the pit probe or the thermocouple? There is already 12V and 5V and 3 spare pins on the CAT5 jack, which could be used to power and connect the thermocouple circuit, perhaps the circuit could be wired to the CAT5 jack on the inside of the case so it wouldn't have to be external?
 
Not a way that I can think of with an AD8495. It outputs direct voltage so you can't have the pullup on the ADC line. That can't be changed by just plugging in something different into the jack. I'm not suggesting the overall HeaterMeter v4.1 be designed in this way, it would just be a way an individual could rig it up.

Even if you wired it into another jack (CAT5) you've still got the problem of having 2 inputs into 1 ADC. I don't want to use another ADC and say "a thermocouple would always be ADC n" because that requires specialized code and I don't feel like it is clean because the function of that one ADC would always be tied to a singled fixed probe. It is much better to support up to 4 thermocouples with the same generic code, but it requires you to build your hardware to the configuration (say probe 0 is always a thermocouple) and having to stick with it.
 
That was the specialization I spoke of. It would remove the "const"ness of the assignments of the probes to their ADC and then you'd need to specify which Probe in HeaterMeter would be the other ADC and the UI would have to enforce only letting you assign one probe as a thermocouple type. It just gets really messy and could be unintuitive.

I think the limitation that "you build your X probe hardware to be a thermocouple and it has to stay that way unless you modify hardware" isn't asking too much. I mean are you going to build a thermocouple pit probe then want to swap it for a thermistor sometimes? I don't see the advantage to being able to do that.
 
Bryan Mayland said:
I think the limitation that "you build your X probe hardware to be a thermocouple and it has to stay that way unless you modify hardware" isn't asking too much. I mean are you going to build a thermocouple pit probe then want to swap it for a thermistor sometimes? I don't see the advantage to being able to do that.
Click to expand...

The only reason I could think you might want that is if you build a thermocouple into one pit, but have several other smokers/grills that you use the HM on which don't have thermocouples built in. I haven't really looked into the cost of a thermocouple vs the cost of the standard maverick probes, if cost isnt a factor then I guess you could just put a thermocouple in each pit. However, it's really only the high heat grills where you would need the thermocouple, for smokers the maverick probes are fine (although not very durable).

Is there any way the HM could be coded to allow you to select which probe is the pit probe instead of having it be probe 0 by default? This way you could build the thermocouple hardware into probe 0, if you want to use a maverick probe as a pit probe on another smoker you would just select a probe with the standard hardware as the pit probe?
 
Getting a quality pre-built thermocouple from auber is roughly the same cost as a Maverick probe, $12 for a K type good up to 900F with a thermowell and screwmount and stainless over fiberglass braid. I'm sure you can get cheap ones from eBay for even cheaper.

It's just a waste of code space and web UI screen area. Sure, one or two people might use it but HeaterMeter is confusing enough without adding more configuration items to support such an obscure configuration.
 
OK, that sounds reasonable. If the price point is similar and they can live in the grill and survive moisture and high heat I am ready to move on it. I wouldn't have a problem buying a thermocouple for every pit I run if that's the only option after installing the thermocouple hardware at probe 0 on my HM.... If and when this becomes available I am ready to be a beta tester....
 
DOH! So i was laying out an AD8495 breakout board in Eagle, and was planing on using a 1/8th inch audio jack, then using a stereo patch cable to connect back to the heatermeter; trying for a design everybody can use even though I have a custom HM build. I though "Oh, I can just remove the pullup resistor from the PIT ADC, then run an air wire from +5v to the unused pin on the probe jack. Then I discovered it was 3 pin, 2 conductor. Face and palm collide! I'm still looking to see if I can find a stereo plug that has roughly the same mechanical footprint.

Bryan, would you ever consider placing the AD8495 circuit directly on the HM board? IIRC recall you wanted to avoid SMD in the past.
 
Last edited:
mmmmmaybe? There's not any space not nowhere on the v4.0 board. The v4.1 board will be larger so if I can fit it in...

No promises, and it will almost certainly require you to have the hardware built one way or the other (as opposed to software selectable or even hardware selectable).

EDIT: Thinking about it, it can't be run to the existing jacks at all. The problem being they have one of their two connectors shorted to ground. I considered making a trace that could be cut to isolate the pit jack's ground, but it sits on a ground plane that's connected to everything. The routing is tough enough to do already without this restriction, so I'm not sure I'll be able to do it at all.
 
Last edited:
Ralph,

Did you have a chance to look at the quality pre-built thermocouple from auber? How will this work for you, and what temp limitations do you still have?

Dave
 
Dave Casazza said:
Ralph,

Did you have a chance to look at the quality pre-built thermocouple from auber? How will this work for you, and what temp limitations do you still have?

Dave
Click to expand...

Although Bryan has built into the software the ability to use a thermocouple the hardware isn't there on the board yet. I haven't gone through the process of rigging up a circuit to connect a thermocouple yet so I haven't really looked very close at any thermocouples. (yet) I doubt that I will be doing this any time soon, because it's winter and I have resigned myself to using the HM over a CAT5 cable so I can keep it inside, and I am not eager to do any experiments running a thermocouple over the CAT5 cable, perhaps in the spring when the weather is pleasant again I might dig into that....

For now I am using Maverick High Heat probes as pit probes when I cook pizza and set my pit temp at 650 max, the high heat probe is good up to a little more than 700 degrees so it works out fine, I just have to make sure I don't leave the pit open too much and let the fire rage so there is overshoot (that peaks above 700 degrees). Pizza's cook fine (GREAT!) at 550-650 degree so I am getting the job done well enough with what I have, for now....
 
Last edited:
I've designed a little board to sit on top of the HeaterMeter v4.1 board that allows you to do surface mount (0805) application of a AD8495. The idea is you cut the two special traces I've put on the pit probe, then put this board down right on top of it where it will mate with the jack pins. Then you run 3V3, GND, and the output to the 3 holes on the HeaterMeter. Then you plug your thermocouple in using a mono headphone male.


For size reference that is 4x size. It fits between the pins of the probe jack which is 0.55"x0.45"


I didn't put the cutway traces on all the probes because it was hard to route them. If it all fits, maybe future versions will be be a daughterboard that goes across all 4 jacks and interfaces directly to the probe pinheader.
 
You must log in or register to reply here.

 

Back
Top