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Cheap Thermocouple Thermometer

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truckmann

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Here is what I recently got to replace all the cheap crappy digital thermometers I have been using. Found a good deal on it so I hope it lasts and works good. It look like the MTC that thermoworks is selling only it is a different color and has a different logo on it. The initial tests look good it's right on at freezing but it was only reading 209-210 in boiling water. Not sure what to think of that. It was very consistent in the boiling water unlike the taylor digital that was supposed to be water resistant. Obviously it isn't even close since I can see moisture fog up the inside of the display and as soon as it gets too much moisture in it, it starts giving all kinds of bad readings.

Details are I found it on ebay under JMS Type K thermocouple, but I bought it directly from the seller NOT using ebay. The guy was very nice, answered my questions and got it to me very quickly. I paid $30.50 shipped with a wire thermocouple that will need some modification to be useful in liquids. I also found a good deal on a 12" type K probe from ebay for $10 shipped. So my total cost in it is $40.50 with the probe.

Anyway here are pictures of my initial tests.

With wire thermocouple


With Probe


In Ice
 
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truckmann

truckmann

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No splitting hairs for me as long as it stays consistent. :)
I am just so sick of digitals that read right one day and off 10 degrees the next so I hope this is the answer without spending a bunch of $$$:D
 

Lil' Sparky

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Can you use that probe in a weldless fitting in a MLT just like you can a regular probe thermo? How sturdy is it? I'd hate to damage it with my mash paddle. It also looks very long. How long is it? Or is this just a sanity check device for digital thermos?
 
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truckmann

truckmann

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Can you use that probe in a weldless fitting in a MLT just like you can a regular probe thermo? How sturdy is it? I'd hate to damage it with my mash paddle. It also looks very long. How long is it? Or is this just a sanity check device for digital thermos?
The probe I got is 12 inches long and it is a little flimsy. Not ideal but it was only $10 brand new. The place I got it from is an overstock/discontinued item liquidator. I looked it up on the place it originally came from and they sold it for a lot more, but that particular one was discontinued. I might buy a piece of larger stainless tubing to reinforce it. I'm still just poking the probe in on top the mash for my temps.

You can get any type K probe with a mini connector an it will work with the thermometer so I'm sure you can find one or have one made how you want it. I plan on using this little guy as a primary thermometer along with my fermentap bi-metal just to have a secondary check when brewing. It's really annoying when you think you are mashing in at 154 and find out it was probably only 148 due to a crappy thermo. I need to check the calibration on the dial thermo in my HLT too.
 
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truckmann

truckmann

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Your location is about 700 feet above sea level. Water boils at 210 in your area.
That's what I was thinking. The calculator that I used was telling me around 211 using the barometric pressure reading at the Airport which is a good 30 minute drive away. So depending on the actual Baro pressure at my location at the time that little thermometer is probably right on.
:mug:
 

JVD_X

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I think you will find that RTD's and Thermocouples are very accurate but they are not necessarily fast.

I just viewed your video... you should give a thermocouple at least 30 seconds before taking note of the temp. In fact, you should apply that to all digital thermometers.
 

tipicreeper

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If you would like to use a cheap thermocouple, you could by a spool of Thermocouple wire and connect the wires at one end.(Twist and put a drop of solder) Instant temp probe.
I happen to find a left over spool of J that I had around. It happens to have a teflon jacket so its good to 500 deg. I was thinking of embedding it an a little piece of tubing.
 
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truckmann

truckmann

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I think you will find that RTD's and Thermocouples are very accurate but they are not necessarily fast.

I just viewed your video... you should give a thermocouple at least 30 seconds before taking note of the temp. In fact, you should apply that to all digital thermometers.
I watched it in the ice and boiling for a few minutes and at those temps once it got the temp in 4-5 seconds it stayed within a degree for the duration I had it in there so I'm pretty confident that after 10 seconds I will know very close what the temp is. Definitely a lot faster than the cheap Taylor that I had which took 10-15 seconds to even get to temp let alone stabilize.


If you would like to use a cheap thermocouple, you could by a spool of Thermocouple wire and connect the wires at one end.(Twist and put a drop of solder) Instant temp probe.
I happen to find a left over spool of J that I had around. It happens to have a teflon jacket so its good to 500 deg. I was thinking of embedding it an a little piece of tubing.
So is there any kind of calibration that needs to be done to make using wire accurate or does getting the right kind of wire take care of that?

Do you need to make sure that the actual wires stay dry? Like getting a piece of stainless tubing to put them in for a probe or can you put the wires directly in liquid?
 

Evan!

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Cool...mine got delivered yesterday too. I spent about twice that much from thermoworks, but as I said in the other thread, after all my thermometer problems in the past (and given that my refund for the previous two was $80 so I'm still back where I started anyway), I'm willing to pay more in order to have a company stand behind their product with a warranty...rather than some dude on eBay. Anyway, mine looks pretty much like yours....gonna try it on on a brew very soon. Thanks again for your and JVD_X's help finding this thing...
 

Evan!

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So is there any kind of calibration that needs to be done to make using wire accurate or does getting the right kind of wire take care of that?
I don't see anywhere on this indicator unit where adjustment for calibration would even be possible, so I'm guessing no.

Do you need to make sure that the actual wires stay dry? Like getting a piece of stainless tubing to put them in for a probe or can you put the wires directly in liquid?
It's my understanding that type K wires don't need to be kept dry---I've seen people just make their own probe by tying the wires together at the end and leaving them bare.
 

flyangler18

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Just picked up one myself, and was wondering about the exposed wire at the end of the probe. Should this be jacketed in a metal probe?
 

tipicreeper

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Yea, a K T/C is chromel–alume both resistant to corrosion so I would say they can be wetted.
A J T/C is (iron–constantan) so I would protect the iron from rusting.
 
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truckmann

truckmann

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Good info here guys! Keep it coming.

So it sounds like I don't really NEED to make a probe in order to use the wire thermocouple that comes with it.
 

tipicreeper

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So it sounds like I don't really NEED to make a probe in order to use the wire thermocouple that comes with it.
That's all that's inside a thermocouple probe. Just connect one end and your good to go. Just as an FYI, if you make multiple connections with the same wire the final reading with be an average of those points.
 
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truckmann

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Good to know. I knew there are wires in the probes. I just wasn't sure if direct contact with the wires in liquid would cause a problem or not. Thanks for the info!
 

mrburnsbud

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for more information about the physics of a ThermoCouple wiki "seebeck effect". Relates temperature to emf (voltage). V = (S1-S2) (T1-T2) where S1, S2 are the seebeck coefficients.
 
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