DIY Thermocouple How-To


 

WBegg

TVWBB Pro
So I finally received some components to start making my own thermocouples, and I was quite surprised with the results.

A thermocouple (k-type) is simply two wires of differeing composition, when welded together, create a voltage. This voltage varies with temp, and it's this voltage that the HM converts to a temperature reading.

Here are the parts, and sources, I used

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K-type Thermocouple Wire (not extension wire!) - http://www.ebay.com.au/itm/391202639262?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Alligator Clips - http://www.ebay.com.au/itm/131595395417?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Connector - http://www.auberins.com/index.php?main_page=product_info&cPath=7_43&products_id=417

SS Sleeve - http://www.aliexpress.com/item/4-30mm-thermocouple-Tube-Stainless-Stell-one-End-Closed-thermowell/1127203684.html

Step 1 - Strip back the steel braiding, and strip the two wires back about 1/4"
Step 2 - Twist the wires together about 2 times.
Step 3 - Weld a bead on the end to connect the wires. I used a 12 v battery with a carbon electrode I stole from an old lantern battery. Simply touch the wires quickly to the electrode, and bob's your uncle!
Step 4 - untwist the wires so only the weld is touching
Step 5 - Cut to desired length
Step 6 - insert into Stainless Steel sleeve and affix with high temp adhesive. Insert sleeve into Alligator clip and crimp
Step 7 - Attach connector.

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Here's the finished product.

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And a "test Burn" next to Maverick and Thermoworks probes. (not sure which one is right, but spot on all 3 at smoking temp)

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WBegg, correct me if I am wrong but going back to my days in the lab, my adviser always told me that the probe end of the thermocouple had to be spot welded because introducing another transition element into the mix will throw off the reading? Yours seem to match the resistance probes pretty well so perhaps the twists of the ends is enough contact to keep the performance intact.
 
WBegg, correct me if I am wrong but going back to my days in the lab, my adviser always told me that the probe end of the thermocouple had to be spot welded because introducing another transition element into the mix will throw off the reading? Yours seem to match the resistance probes pretty well so perhaps the twists of the ends is enough contact to keep the performance intact.

Tom, maybe you mis-read. I did spot weld the ends (with a 12v battery and carbon electrode). The twisting was just to get the wires aligned, then untwisted after welded.
 
Tom, maybe you mis-read. I did spot weld the ends (with a 12v battery and carbon electrode). The twisting was just to get the wires aligned, then untwisted after welded.

Ah, when you wrote 'welded a bead' I thought you meant some sort of soldering.
 

 

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