Better probes?


 
That's the method I've suggested before, I just haven't done it. You can set the setpoint to "0R" which will display the resistance for the probes (all of them) which might make it easier.
 
I see that there is now a preset for "Thermoworks Pro-Series High Temp TX-1001X-OP" in the configuration page. Are these coefficients accurate?
 
Darn. Was hoping to buy one of those probes because they look like they'd have far less moisture problems than the mavericks. I saw one of your earlier posts that it was not possible to get the coefficients to match at both ends of the curves. Do you think that these probes just don't follow the normal equation? Or is it that it's just difficult to calculate the coefficients precisely? I have calibrated temperature forcing equipment and precision multimeters in the lab here so if it's just measurement difficulty that prevents obtaining the proper coefficients I should be able to work around that aspect of the problem. However, if the probes don't follow any known "normal" equation that I'm not sure that would help much.
 
And I got excited and ordered 2 Thermoworks after 1 of my Mavericks died this weekend........ Oh well, I can live with being a few degrees off on the low end.
 
T Hayes said:
Do you think that these probes just don't follow the normal equation? Or is it that it's just difficult to calculate the coefficients precisely?
Click to expand...
All NTC thermistors follow the same basic equation so the only thing holding it back is accurate data measuring resistance vs temperature over the desired range. I will do this (at least as accurate as I can) but haven't had time. I need to modify the linkmeterd to support logging that much data, then actually do the test run.
 
I know you don't yet have the proper coefficients, but have you made an initial quality assessment of the thermoworks probes? Do they seem much higher quality and less likely to break than the maverick probes?
 
What the heck, 3D printing can wait another day.

I went through the trouble of modifying all the linkmeter code and tossed two probes in my convection oven. Once the temperature settled at the max the oven will go, I turned it off and turned on the unknown probe calculation. When the oven cooled to about room temperature I recovered the data and pumped it into AN2395. RANGE CHECK ERROR. Great!

I created a new application to calculate the coefficients using some of the source code from the original app. It is rough but it works. The ThermoWorks probe does react faster than the Maverick probe does so the numbers aren't totally accurate. I can also only get the little oven up to 400F, so the numbers beyond that may not be great either. How much are they off? It is a mystery! I'm now waiting on a new set of data to run it against.
 
T Hayes said:
I know you don't yet have the proper coefficients, but have you made an initial quality assessment of the thermoworks probes? Do they seem much higher quality and less likely to break than the maverick probes?
Click to expand...
I don't have Maverick probes consistently fail on me. I use ET-72/73 high heat probes and I've never burned one out, but occasionally (once in 5-10 cooks) I will get a food probe that will get some wonky readings for an hour or so. Not sure if it is because of the fire heating the probe metal bit and transferring it to the thermistor or just bad wiring.

Because I can't get them to consistently fail, I have a hard time saying if the ThermoWorks are any better. They do react faster and I haven't seen one give bad data yet, but I haven't used them that much either so it could just be luck so far.
 
New, slightly better coefficients for the ThermoWorks probes: 7.7012373E-004,1.9712928E-004,2.3049218E-007

This gets them to track within a degree or two of my Maverick probe, from 80F to 425F. They react more quickly so expect them to lead any Maverick probe by at least 30 seconds when there's any appreciable temperature change (10F or more).
 
Wow that was quick! I ordered 2 of these probes, but they won't be here until next week. I'll run them through a temperature characterization to see if I get similar coefficients as you.

The fact that they react more quickly than the mavericks should be a good thing, right? However, that may require tweaking of the PID values.
 
New coefficients from a 550F->77F 2114 point correlation with the Maverick probe. A keen eye will note these are slightly different than I posted in the other thread because when I graphed the data, there was one point that was WAY outlier so I've adjusted it.

Thermoworks TX-1001X-OP: 6.6853001e-04,2.2231022e-04,9.9680632e-08
 
Brian Hilgert said:
Which is what led me to this:



This would have you add a jack to your thermocouple, and make the board modification i mentioned earlier. I am going to send these off to Dorkbot today or tomorrow. I don't know if it will work as I intend, but at .34 sq inches, I can certainly test my ideas with some unpopulated boards.

The idea is you would cut the current traces leading to the pit prob jack, and solder this mod chip onto your HM4 board at the pit probe junction. I've looked into using this kind of jack (i hate calling them phone jacks, i've always called them stereo jacks. Phone jacks are rj11's or rj12's, like on a phone cord :p) and the general consensus is it won't distort the cold junction calibration more that a couple of degrees. At 600c, i can handle a few degrees of error. Anyway it's just an idea, and it will be cheap to test.

Ralph, I though you were considering/ had already added a RJ45 female to your heatermeter, then running an Ethernet cable to an external fan/servo/probe box. If that is the case, you would be better off placing the ad8495 circuit in that extension box. You'll need ground, 3.3v (or 5v if you are already running 5v to the box)and the pit adc. Otherwise your cold junction calibration could be way off.
Click to expand...

Brian any update on this?
 
I checked your coefficients in boiling water. I compared to a maverick 732 probe, and a thermoworks instead read thermometer(not a thermapen). The calculated theoretical boiling point of my elevation is 211.9F

Results:
Thermoworks probe: 214F
Maverick 732 probe: 216F
Instant read: 211.5F

They're not identical, but seem close enough for any practical purpose. I should probably ohm out my 10k pullup resistors, to see if they may be the source of some of the error.
 
I just got those and just in the air and these settings it is reading in the low 100's. I haven't tested in hot water or anything yet but is this typical for these probes to register higher in the ambient temp?
 
No, they should read ambient temperature at ambient temperature :-D With these coefficients 6.6853001e-04,2.2231022e-04,9.9680632e-08 they're within a degree or two at 75F for me.
 
I am using the TX-1001x-OP and I was using the presets offered in the software - is that correct?

EDIT: I tried these three numbers: 6.6853001e-04,2.2231022e-04,9.9680632e-08 in A B C and it didn't change anything?

Thanks,

Neil
 
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It should change something, the defaults in the software are 0.00054037594,0.00023919103,4.6654582e-8 so there should be at least some slight difference between the preset and the numbers I posted. You did save the changes, right? Either that or the one probe I have is vastly different than the probe you got.
 
User root setting 18 values...
pidb to 4 = OK
al to -40,-200,-40,-200,-40,-200,-40,-200 = OK
pn0 to Probe 0 = OK
pidp to 3 = OK
pc2 to 0.00023067436,0.00023696599,1.2636415e-7,10000,1 = OK
sp to 225 = OK
pc1 to 0.00066852998,0.0002223102,9.9680614e-8,10000,1 = OK
pidd to 5 = OK
ld to 6,240 = OK
lb to 50,255 = OK
pidi to 0.005 = OK
po to 0,0,0,0 = OK
pc0 to 0.00023067436,0.00023696599,1.2636415e-7,10000,1 = OK
pn2 to Probe 2 = OK
pn3 to Probe 3 = OK
fn to 10,100,0 = OK
pc3 to 0.00023067436,0.00023696599,1.2636415e-7,10000,1 = OK
pn1 to Probe 1 = OK
Done!
 
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