🌡️ Thermocouple connectors and adaptors - any to be found?

Hello @electrotechs - I see that we have at least 2 devices in the space that one can use to read off the temperature from a thermocouple (pictured below)

1 ~ The RS Stk No. 610-067 Digital Thermometer

2 ~ The Keysight U1232A Multimeter

To connect a thermocouple to either device, one needs it to have the kind of connector shown below:
image
You need the additional adaptor, shown below, to then connect to the multimeter:
image

:thinking: Are we likely to have either of these components in the space?

They don’t ring a bell, but that doesn’t mean we don’t have them.

We do have crocodile clips, I’m not sure what added functionality these clips have.

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Good suggestion - I can try banana from the multimeter to crocodile, with the crocodile clips on the exposed thermocouple leads! No obvious reason it won’t work :thinking::thinking::thinking::thinking::thinking::thinking:

https://www.tc-inc.com/thermocouple-wire/thermocouple-connectors.htm

We have screw blocks too

Im not an expert, but I’ve always thought you shouldn’t extend thermocouples (unless its with specific wire). So you may get inaccurate results using crocodile clips (or I am misremembering something, who knows.)

Yeah - you’re right. It doesn’t work (I tried, though I had heard something like this before as well)

As in - we (SLMS) have the product you shared a link to, somewhere?
I’ve ordered some of Farnell for now.

Thermocouples need dedicated adapters and connectors, from what I know and have seen in various labs. Hence why I focused on the products in my original post.

I wanted to add to this thread as my efforts in thermocouple temperature measurement have advanced, in case useful for anyone else.

TL;DR I don’t think we can get the temperature function on the Keysight multimeter to work without a fancy Keysight adaptor.

The rest below is if you want to use thermocouples in SLMS and get a sense for where to begin, alongside a guide like this one: https://uk.rs-online.com/web/content/discovery/ideas-and-advice/thermocouples-guide


(1) What kit we have in the space:

(a) a somewhat aged but perfectly functional RS Digital (thermocouple) Thermometer. No manual for it online. It takes at the top the 2 pins of a Miniature Thermocouple Connector Plug as shown below.
An example of this connector type is here: https://www.labfacility.com/miniature-thermocouple-plug-type-k-iec.html

It explicitly says on the front of the device that it wants Type K thermocouples only. For some reason it stays on if the battery is plugged in, (even if the front switch is in the ‘Off’ state) so removing the 9V battery after use is necessary.

(b) a somewhat distressed but working thermocouple. Type K!

(For a guide on this categorisation of thermocouple types, do check this out, same guide as I linked at the top: https://uk.rs-online.com/web/content/discovery/ideas-and-advice/thermocouples-guide)

It works. It has that compatible plug connector that fits the RS reader. :white_check_mark:

(c ) The Keysight U1232A Multimeter. If you look closely, you can see a little orange thermometer symbol at about 4’o clock on the dial. This device should be able to give you a temperature reading from a thermocouple as well if you turn it to that setting and hit the orange ‘Esc Shift’ button

Here is the manual for it: https://www.keysight.com/gb/en/assets/9018-03489/user-manuals/9018-03489.pdf?success=true

UNFORTUNATELY it is not as simple as is implied by the picture below, where you just need any old adaptor that goes between the thermocouple plug and the banana sockets on the multimeter


Even though everything plugs together and is at least intuitively supposed to work, Keysight do not expect it to be so simple and the manual also tells you to get a more expensive adaptor:



Image above from: https://www.keysight.com/gb/en/product/U1586B/temperature-module.html

If you plug together the black adaptor and the thermocouple as shown in my photo above, the multimeter just reads ‘zero’. :disappointed_relieved:

(2) Thermocouple connectors
Given that the space only has the 1 thermocouple, it is worth knowing how to ‘make your own’
Picture below is how I combined the thermocouples I purchased with the right connector:

Thermocouples (without the plugs, as on the left): https://uk.rs-online.com/web/p/thermocouples/6212158?gb=a
:point_right: I wanted them with bare wire on the ends so I could use them in this product which allows you to measure temp via a Raspberry Pi: https://thepihut.com/products/eight-thermocouples-daq-8-layer-stackable-hat-for-raspberry-pi

Plugs: https://cpc.farnell.com/labfacility/im-k-m-iec/type-k-connector-plug/dp/SN35314

Of course, you could also order something like this where the thermocouples come WITH the plugs on the end! https://uk.rs-online.com/web/p/thermocouples/3630250?gb=a

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£70 / OBO?

Worth it? Pledge Drive?

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Let’s wait a bit and see if anyone else is into using thermocouples :slight_smile:

They are useful for monitoring temperatures of surfaces you can’t see !

When I needed a thermocouple, I got three of the complete units for under 10 quid. You can cross check them and do the classic boiling water/ice bath calibration.

Logging is via a camera though, unless you get fancy

What did you plug the thermocouples into to read / log their values?

Something like this: https://www.ebay.co.uk/itm/192074152667. Has a calibrated amplifier, lcd, K type thermocouple, and mine had a 9V battery included. You can probably do even better than £4.88 plus battery if that’s your thing.

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I have no idea why multimeter companies charge for these specialist adaptors so they can read out a thermocouple, when there’s tons of products out there that do it just as well - as evidenced by your eBay example!

That looks like it can be an interesting DIY project, Agilent does extend the signal dynamic range to increase the SNR of test results.

It seems like you can use an amplifier circuit with a voltage gain of around 25 to do the same thing. Or use an MCU with high resolution ADC and DAC for a better linear compensator.

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