Forum - Recent Threads

RE: Thermistors Tutorial by Adafruit

robogary — Fri, 02 Dec 2022 17:15:55 GMT

Wow, thanks Nico ! I was using an excel spreadsheet to plot the thermistor resistances VS temperature, to create an equation to fit the curve. This is so much easier.

Thermistors Tutorial by Adafruit

ntewinkel — Sat, 30 Jul 2022 19:37:29 GMT

Hi All,

I thought I'd share with you this excellent tutorial by Adafruit.

https://learn.adafruit.com/thermistor/using-a-thermistor

I found it very helpful in terms of better understanding all the basics of using a thermistor, but more importantly (for me anyway) they do a really good job of explaining and simplifying the equations both in terms of calculating the resistance, but also in terms of converting the resistance to a temperature using the Steinhart-hart equation. Plus I like the clear examples and explanations that go with it.

They make their code available with MIT license, and simply ask that you give them credit and consider buying their hardware once in a while (you can buy Adafruit hardware via the element14 / Newark / Farnell stores).

I hope everyone is enjoying the experimenting!

All the best,
-Nico

Finisher's Prize - Duratool 129 PCS tool set

rsjawale24 — Sat, 29 Oct 2022 15:45:39 GMT

Today I received a package from element14. The box contained finisher's prize for the Experimenting with Thermistors challenge - A duratool 129 PCS tool set.

I'm thankful to Molex and e14 for organizing the contest and providing prizes.

One can never have enough tools. The tool set consists of useful tools as shown in pictures below

RE: Finisher's Prize - Duratool 129 PCS tool set

rsjawale24 — Mon, 31 Oct 2022 07:58:16 GMT

Yes and it's easy to carry around too!

RE: Finisher's Prize - Duratool 129 PCS tool set

colporteur — Sun, 30 Oct 2022 16:53:27 GMT

Nice selection of tools in the kit. A kit to keep in the car for those times when a quick fix with a tool is what you need.

RE: Thermistor Fixed Point Math

shabaz — Mon, 19 Sep 2022 15:42:48 GMT

Interesting results!

Python on the Pico has issues too. It got to the point with Pico MicroPython (and CircuitPython) were so restrictive with their single-precision that I just built my own double-precision version for MicroPython, and just use that now, to reduce such unexpectedness when working in that language. CircuitPython has all sorts of maths anomalies (and not just in maths either).

I'm storing the MicroPython builds here: https://github.com/shabaz123/PiPicoMicroPythonDoublePrecision/tree/main

However, even double-precision isn't always precise, I wish a quadruple-precision build was available! There are libraries for that but they are for Python, not MicroPython.

Thermistor Fixed Point Math

scottiebabe — Sun, 18 Sep 2022 23:34:06 GMT

Soft 404

Is Ice water a constant temperature?

scottiebabe — Fri, 12 Aug 2022 16:07:57 GMT

Soft 404

RE: Is Ice water a constant temperature?

Jan Cumps — Fri, 16 Sep 2022 12:54:34 GMT

[quote userid="395267" url="~/challenges-projects/design-challenges/experimenting-with-thermistors/f/forum/51507/is-ice-water-a-constant-temperature/200559#200559"]Perhaps it was just bad timing,[/quote]

Story of my life

RE: Is Ice water a constant temperature?

scottiebabe — Fri, 16 Sep 2022 12:20:10 GMT

RE: Is Ice water a constant temperature?

Jan Cumps — Fri, 16 Sep 2022 07:27:37 GMT

It also shows in the main article now 🤔

RE: Is Ice water a constant temperature?

bryanlowder — Fri, 16 Sep 2022 05:25:03 GMT

Thanks.

RE: Is Ice water a constant temperature?

Jan Cumps — Thu, 15 Sep 2022 19:38:02 GMT

Yes

RE: Is Ice water a constant temperature?

scottiebabe — Thu, 15 Sep 2022 18:48:03 GMT

RE: Is Ice water a constant temperature?

Jan Cumps — Thu, 15 Sep 2022 18:31:36 GMT

[quote userid="395267" url="~/challenges-projects/design-challenges/experimenting-with-thermistors/f/forum/51507/is-ice-water-a-constant-temperature"]During my 5 minute stirring marathon[/quote]

The image below that line doesn't show

RE: Is Ice water a constant temperature?

wolfgangfriedrich — Thu, 15 Sep 2022 11:39:58 GMT

This experiment is part of a design challenge, where the contestants got handed a kit of components.

Here is a link to the kit including the part number to the elusive 10k thermistor.

RE: Is Ice water a constant temperature?

bryanlowder — Thu, 15 Sep 2022 06:09:03 GMT

I've seen a few articles blithely mentioning the Molex 10k thermistor, but, erm, what's the actual part number? Is it just too obvious to mention?

Compensating for Leakage Current in Thermistor Measurements

scottiebabe — Thu, 08 Sep 2022 16:53:27 GMT

Soft 404

Are Molex thermistors water resistant?

scottiebabe — Tue, 19 Jul 2022 14:53:09 GMT

Soft 404

RE: Are Molex thermistors water resistant?

misaz — Wed, 07 Sep 2022 18:56:41 GMT

Yes, I did. I received it approx 3 days after I was posting coment above. I already posted some blogs. You can see one of my thermistors from the kit for example here: Blog #2: Thermistors Minitutorial Part 1 - Measuring temperature using thermistor and multimeter.

RE: Are Molex thermistors water resistant?

rscasny — Wed, 07 Sep 2022 16:05:06 GMT

Did you receive your kit?

Randall

RE: What's better than one thermistor?

shabaz — Mon, 29 Aug 2022 23:01:49 GMT

I really hope you get it to work! It would be an awesomely low-cost way to get excellent measurements for (say) ambient temperature, since thermistors can cost just pennies, and lots of room thermostats perhaps uses cheap silicon sensors (not the good ones) - at least the one I have at home is really bad.

The main problems I was getting in the limited time I was testing the dual thermistors, was that despite the environment getting warmer, I'd see the measurement sometimes drop, i.e. it was not monotonic, presumably because one thermistor was warming up before the other one, even just 5 mm apart, and for me the error was quite high too, although perhaps a better computer simulation could have picked an improved combination that could handle such differences better until both thermistors reach equilibrium. Bonding two thermistors could be neat too. One thing I wanted to experiment with was to bond a thermistor to a 50 ohm resistor, to make a cheap RF power meter. I bought some 0402 thermistors and 0402 50 ohm resistors to attempt that, but it's so fiddly : )

Have You Ever Tried Creating a Synthetic Resistor with Thermistors?

scottiebabe — Mon, 29 Aug 2022 17:05:02 GMT

Soft 404

RE: What's better than one thermistor?

scottiebabe — Mon, 29 Aug 2022 22:45:03 GMT

RE: What's better than one thermistor?

shabaz — Mon, 29 Aug 2022 22:11:14 GMT

Just wondering if you've tried it for real : ) I attempted to linearized with two thermistors, but didn't get great results : (

I didn't spend long enough to figure out why, but I suspected it could be because they were not thermally coupled, they were separated by about 5 mm. It may work better if they are thermally glued together maybe! I had tested with SMD thermistors (I think they were 0603), to measure air temperature, and maybe the low thermal mass was exacerbating the problem.

There are ready-made dual thermistors that are in a single package, and they provide great results, so that was the reason why I thought maybe the separated ones were not functioning well.