Better probes?


 
Good question. Thermoworks makes really awesome stuff, I didn't realize they had expanded their product line so much to include thermistor-based equipment. At least I think this is thermistor-based, all the thermocouple models explicitly say so. The real question is if we can get a datasheet for the thermistor used to get the Steinhart coefficients for it.

I'll put one of these on my "to buy" list next time they have a thermapen sale. I've wanted to pick a new one up ever since my original non-splash-proof model took a swim in a pot of hot sugar water and since has been difficult to use.
 
Thank you for posting this. I am hoping they work out and play nice with the HM, cause I have about had it with Maverick probes. The Maverick probes work but they are not very durable at all, a little water or too much heat and they are history. (although I actually had one hit 785 degrees last night during the warm-up for a pizza cook and not die, I've had others die from just a little water and had "high heat" units die at under 700 degrees)

Bottom line, I would like to use something better, having more resistance to moisture would be a real plus...
 
Kyle Christensen said:
Only downside, they don't look like they'd fit through my WSM grommets. :(

I do love my Thermapen though, I use it constantly.
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I hadn't thought of that, but you're right... I poke the probes through a smallish hole on the side of my smoker and I don't think their connector bump will fit through.... I guess I could make the hole bigger or find another way to get them inside the smoker, but that would be one negative aspect of this probe design....
 
What can brown do for me? Hopefully not get filled with sticky sugar! Thanks for passing this on, just ordered a thermapen and one of their temperature probes.
 
Bryan Mayland said:
What can brown do for me? Hopefully not get filled with sticky sugar! Thanks for passing this on, just ordered a thermapen and one of their temperature probes.
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Bryan,

I will be very anxious to find out if the Thermoworks probe works for you. I think yesterday was my 4th cook with the Maverick probes. I bought 2 of them to start with. In mid cook yesterday, the pit probe jumped from 225 to over 350 degrees. I guess it's toast. I'd rather invest in Thermoworks than buy a new Maverick probe every 4th cook.
 
Darren C. said:
Bryan,

I will be very anxious to find out if the Thermoworks probe works for you. I think yesterday was my 4th cook with the Maverick probes. I bought 2 of them to start with. In mid cook yesterday, the pit probe jumped from 225 to over 350 degrees. I guess it's toast. I'd rather invest in Thermoworks than buy a new Maverick probe every 4th cook.
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I'm with you on that, I have had too many maverick probes die on me. They are ok when they are working, but are not durable at all....
 
Good news. I originally purchased the Maverick probes using this link. I contacted them about the problem that I experienced. They sent me a new probe, no questions asked. They didn't even ask for the broken one back. The service was excellent.

I immediately plugged it in. I've had the HM running all day in the house. I noticed that the broken one, which had been off by 100-150* F had settled in at consistent 10* F above the good probe. Incidentally, you can also see where I plugged the new probe in. Do you think the broken probe can be salvaged?

9729289562_b1ded58729_c.jpg
 
I've been running some chepo's I bought off ebay for a couple of years now. Worst problem I've have is if it they get wet and I have to let them dry out for a few days. I think I bought for w/ shipping for under $25. Calculating the Steinhart was fun (way back before unknown probe detection.
 
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Brian Hilgert said:
I've been running some chepo's I bought off ebay for a couple of years now. Worst problem I've have is if it they get wet and I have to let them dry out for a few days. I think I bought for w/ shipping for under $25. Calculating the Steinhart was fun (way back before unknown probe detection.
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What kind of probes? I've been through quite a few Maverick probes already, getting pretty sick of buying new ones.....
 
Cdn ad-dtp392

They are CDN replacements, the specific model is AD-DTP392. I use them for both pit and food probes. I just found some on both e-bay and amazon. I have had one or two instances where one went off, but I could always attribute it to being left on the smoker in the rain after the previous cook. If I just leave them in for the next smoke, and give them a good place to dry after, they work fine. I usually just place my 'ambient' probe in the pit as a backup if I'm not going to be hanging out by the smoker, just to be safe ;-)

I'm actually running an old version of the web gui, so I hard coded the steinhart's into the atmega. I though I read somewhere that you can set those from the web:eek: I really need to update my HM, Life just kept me away from it for awhile, and now I'm playing with Thermocouple integraton :D
 
Brian Hilgert said:
They are CDN replacements, the specific model is AD-DTP392. I use them for both pit and food probes. I just found some on both e-bay and amazon. I have had one or two instances where one went off, but I could always attribute it to being left on the smoker in the rain after the previous cook. If I just leave them in for the next smoke, and give them a good place to dry after, they work fine. I usually just place my 'ambient' probe in the pit as a backup if I'm not going to be hanging out by the smoker, just to be safe ;-)

I'm actually running an old version of the web gui, so I hard coded the steinhart's into the atmega. I though I read somewhere that you can set those from the web:eek: I really need to update my HM, Life just kept me away from it for awhile, and now I'm playing with Thermocouple integraton :D
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Care to share the coefficients? Those are the exact ones I have - that I've been working on calculating... unsuccessful on round #1. I think I need to let temps stabilize before taking readings
 
I got the Thermoworks probe in the mail yesterday. First impressions. The wire is nice and sturdy. I've bought some "Original Maverick Probes!" off sites that came with some pretty thin cabling and failed pretty quickly but not these. The long list of usage information on the back of the package specifically warns against getting them pinched in a lid to prevent breaking the wires. The tip is really small and the resistance changes quickly with temperature. The junction between the wire and the probe also is fully enclosed which should provide better moisture resistance than the crimped Maverick-style junctions.

Good news is the probes fit snugly into the HeaterMeter probe jacks-- none of that ET-732 garbage. They're 100k thermistors rated -50C to 300C, so the only matching part I can find across all suppliers with the proper dimensions is Semitec 104GT-2. Not sure how easy it is going to be to calculate the steinhart values in an accurate way.

EDIT: Also forgot to mention that Analog Thermocouple software support is in git now.
 
It took me a while to dig them up, but here is what I used for the CDN probes, straight out of my hmcore.cpp:

{5.7079876e-4,2.1810467e-4,5.0643855e-8,2.17e+4}, // CDN Probes

Software side for themocouple is done? great! I just finished a rework (a minor one at that)of the HM 4.0 board to add the AD8495 circuit to the board. I opted to go with 603 size caps and resistors; I figure if I have to solder a MSOP8, 603s would be easy. Then I got to thinking it would be cool to make a 'mod chip' so that users could easily modify an existing HM4 to support K type thermocouples. I'm about to send that off to dorkbot today. I think cleaning up the silkscreen is/was harder than placing the components and routing the signals...
 
Has the hardware for the thermocouple interface been decided on then? Is there a diagram available somewhere? I have a spare HM board here and would like to experiment with a thermocouple as a pit probe... I assume it will have to be an off (HM) board circuit (at least for now), but I would be glad to participate in the thermocouple experiments to help develop this aspect/option...
 
I think the only thing that has been decided upon is the use of an analog chip, namely the AD8495, as Bryan suggested in the high heat thread. I just got boared one night and decided to see if I could squeze one with the required components onto the exiting HM4 design. It was a labor of love, but it can be done.

HM4-TC-1.png
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I only had to move one existing trace, as indicated by the pink arrow. In it's current design, the board is still set to use a standard thermistor probe. One need remove the pull-up resistor from pin 28 on the atmega, cut the ADC trace to pin 2 of the pit probe jack ( close to the jack, the trace to the probe header is used by the AD8495), and cut the ground plane connection to pin 1 of the probe jack. I did verify ( in Eagle) that cutting the ground trace around pin one of the probe jack will not interrupt continuity of the ground plane with other components.

I'll post the 'mod chip' style later, but it is an identical layout, it just utilizes airwires to connect to GND, +3.3v, and the atmega. I need to adjust a few things, namely the solder pads for the jump wires seem a little small.
 
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