Making A Thermocouple
This document was uploaded by user and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Report DMCA
Overview
Download & View Making A Thermocouple as PDF for free.
More details
- Words: 2,901
- Pages: 5
Home Sign Up! Explore Community Submit
Making A Thermocouple by trebuchet03 on November 21, 2006
Table of Contents intro: Making A Thermocouple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
step 1: Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
step 2: Actually Making The Thermocouple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
Video . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
step 3: Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
step 4: Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
Related Instructables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
Advertisements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
Customized Instructable T-shirts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
http://www.instructables.com/id/Making-A-Thermocouple/
intro: Making A Thermocouple A thermocouple is a device used to measure temperature by utilizing the Seebeck effect. This instructable will show a very simple method of making a thermocouple so you can precisely measure the internal temperature of your thanksgiving turkey. I'm sorry that the one picture I have came out terrible. The picture with the flash off was even worse (low battery syndrome). I was debating weather or not to post - but considering I couldn't find instructions anywhere on the web on how to do this, I decided to go forth and conquer. At least the video in step 2 is somewhat amusing. If I can - I'll build my own bridge and make my own meat thermometer probe. Why? you ask. Why not? What's cooler than measuring the temperature of your turkey with your trusty multimeter. And in my case, my trusty cheapo multimeter and calculator :P
step 1: Materials 1. Thermocouple wire : we got ours from http://www.omega.com/prodinfo/ThermocoupleWire.html You can probably do it with your own wires - but the must be dissimilar materials and your results may vary. If the materials are not suitable, you will know as soon as you try to calibrate. 2. A capacitor bank or other method to spot weld a tiny wire.
step 2: Actually Making The Thermocouple 1. Strip back the outer insulation 2. Strip back each individual wire and expose about .24-.5 inches of wire. 3. Bend the wire to make a contact point** 4. Weld (see next step for a suggested setup). Now you can use your thermocouple (a whole other set of instructions). We used Labview 7 a DAQ board and a conditioner board (which provided a 1/4 Wheatstone bridge).
Video
**If you have more than one contact point, you're measurement will be the average temperature over all of the contact points rather than the temperature at the contact.
http://www.instructables.com/id/Making-A-Thermocouple/
step 3: Welding We had a fancy little device that provided a ground (pliers) and a hot "plate." We would grasp wire in contact with the pliers and touch the hot plate (closing the circuit). A high amperage discharge would occur and the wire would spot weld. I suspect it was a capacitor bank. All you'd need is a sufficiently large bank of charged caps. Take a pair of insulated pliers and attach the ground wire to an exposed bit of metal. Then grasp your thermocouple wire in the pliers and touch the positive end of the charged cap bank. I would personally start small and add caps as necessary ;)
step 4: Calibration Okay, so lets say you have the tools to use your Thermocouple (I don't, but the measurements lab did). As with any other measuring device, you must form a calibration curve to show your measurements are accurate/precise and credible. Given the tools/supplies available. We made an ice water bath and a boiling water bath. Ideally, we would have added salt to the water to help it get colder. We used a normal thermometer to measure an analog temperature. Then, we started recording the thermocouple data in Labview and went from the room to the ice water bath. We saved this data and repeated for the hot water bath. As thermocouples have a linear relationship to temperature, linear interpolation can be used to determine any temperature within the thermocouples range. You can also determine the response time of the thermocouple based on the data collected.
Related Instructables
Statistical Analysis of Turkey Cooking by trebuchet03
Temperature Control For Kitchen Appliances by timothy
Weekly Project: Hottie Hoodie-Be a Walking a Weather Station by PopSci
Be a Scientist: Make your own thermometer by Kiteman
Advertisements Customized Instructable T-shirts
http://www.instructables.com/id/Making-A-Thermocouple/
3D chocolate printer made from LEGO by saul
Illustrated Turducken Recipe by kachun
Toaster Oven Reflow Soldering (BGA) by colin
Multifunction Digital Thermometer by J_Hodgie
Comments 15 comments Add Comment
android_18 says:
Nov 28, 2008. 1:27 AM REPLY
is it possible to construct a thermocouple which could produce 3 volts or higher?
royalestel says:
Jun 5, 2007. 9:06 PM REPLY
Cool! Favorited!
NachoMahma says:
Jun 1, 2007. 1:13 AM REPLY Great job! A few comments. 1) TCs are not linear, especially at the extremes of their ranges. That said, for most DIY purposes (0-100 degC) "common" (J/T/K) TCs are close enough. 2) I like to do a third calibration check at a temperature close to what I expect to measure (usually ~50% full-scale), but I'm a bit compulsive (13 yrs as an Elect/Instr Tech). 3) Make sure you use actual TC wire and not extension wire if you are concerned about absolute accuracy. Extension wire is OK if you're only worried about repeatibility. 4) I haven't looked at one in a while, but the Omega Product Handbook for Temperature Omega() was my TC Bible back in the 80s-90s.
godot01 says:
Feb 24, 2007. 10:50 PM REPLY
I guess it depends on the application but welding a thermocouple seems like overkill. We always silver solder them. We read them out thru a fluke t/c reader or a micromite. Just twisting T/C wire is generally good enough for many applications although not very durable. If this is not accurate enough for your application then a T/C is probably a bad choice anyway. We use RTDs in some applications.
0.775volts says:
Nov 30, 2006. 8:52 PM REPLY OK, you did a good job making your thermocouple (I commented on making thermocouples in that instructable that was either about spot-welding, or playing with a big-ass capicitor bank, i can't remember which). ok, the best way to explain this is to highlight the process by which a friend and I have made these before. sorry if i'm a bit stylistic grammatically, i'm not on my first beer of the evening. ok, so take your length of thermocouple wire (I prefer type t) cut the jacket off the conductors, and strip both of them approx 1/2" on one end of the thermocouple wire, twist the conductors together. connect this end to the + side of your capacitor bank/welder/bigass current source on the other end of the thermocouplewire: take the conductors and cross them right where the insulation ends. twist them together as tightly as possible and cut them after one good, tight twist. then, take something conductive and flat and connect it with a big-ass wire to the - side of your current source. get a pair of needle nose pliers, clamp them on to the thermocouple wire about an inch away from the free end. wrap a rubber band/string/hairtie/whatever around the handles of the pliers so they stay clamped on the wire. put on welding guantlets and sunglasses and charge your current source once charged, pick up the needle nose pliers and get ready to spot weld the thermocouple to spot weld, just touch the thermocouple wires to the metal plate, creating short circuit and welding the metals together. pull it away after about 1/10 of a second, ie: get a good pop and move it away and you're done. if you stick it togeter for longer, you're likely to melt something and start a fire. we've done this many times, and it produces a good thermocouple. of course, you'll need to calibrate it when you use it, but you always did that with new thermocouples anyway, right?
trebuchet03 says:
Nov 30, 2006. 9:07 PM REPLY We're required to calibrate everything every time we use it ;) Even if Tcouple, transducer, scale etc. etc. came with a calibration chart - we are required to re-do it. These thermocouples were used for an exercise in calculating time constants and comparing to soldered connections. When a thermocouple has more than one contact point (such as wrapping onto itself) your measurement will change - instead of measuring at a point - you'll be measuring the average of the connection points. For the purpose of our lab, wrapping would give inaccurate results (higher time constants). Don't get me wrong, your method works too (just not so well for our application :P).
0.775volts says:
Dec 1, 2006. 1:23 PM REPLY I'll have to send you pictures of our set up, we wrap and cut after the first wrap to have enough material to spot weld the wire, it makes a little blob that is solid, so there is only one (rather large) contact point. we had that issue with some of the first thermocouples we built, they were all over the place in terms of response. that's when we realized we needed to change our method (it took us 50' of type T wire to figure out where we were going wrong). when I'm back in my home town for the holidays, I'll duplicate the setup and take pictures so you can see what I'm talking about.
http://www.instructables.com/id/Making-A-Thermocouple/
ewilhelm says:
Nov 21, 2006. 6:14 PM REPLY
You are now required to post a time/temperature plot of your turkey!
trebuchet03 says:
Nov 23, 2006. 12:46 AM REPLY
"Just for fun" - I started writing an instructable titled: "A Statistical Analysis of Turkey Cooking." I've already come across some interesting little tidbits about turkey geometry and how they play a role in cooking time :P I think I've brought myself to a new dork low (or high?) :P
vatosupreme says:
Nov 21, 2006. 8:06 PM REPLY
Yeah, but we need the data in real time on instructables. So how about hooking it to a webserver :P
zachninme says:
Nov 23, 2006. 8:40 PM REPLY
That would be awesome! Stick in about 10 probes, and make a small AJAX site to display info, and allow us to yell at you when you should do something :-)
Oracle1729 says:
Nov 22, 2006. 2:05 AM REPLY You're putting 2 dis-similar metals into the meat. The meat will act as an electrolyte and you'll have a simple battery. The effect will be metal ions flowing from your thermocouple into the bird. Most metal ions are toxic except in tiny amounts.
trebuchet03 says:
Nov 22, 2006. 9:07 AM REPLY
It can be put in an inert carrier without changing its ability to measure temp (although it may increase response time).
Oracle1729 says:
Nov 22, 2006. 2:44 PM REPLY
Of course it can, and that's what a commercial unit does. However, this instructable shows using it directly without an inert carrier, so using it as shown here will posion the meat.
trebuchet03 says:
Nov 22, 2006. 9:36 PM REPLY
Fair Enough :) I also found out today that the wire insulation is not food service safe. Not sure why though -- maybe lead or something? So, for said time/temp plot - I got a cheap meat probe ($15) and I'll keep record :) I'll even calibrate it :P
http://www.instructables.com/id/Making-A-Thermocouple/
Making A Thermocouple by trebuchet03 on November 21, 2006
Table of Contents intro: Making A Thermocouple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
step 1: Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
step 2: Actually Making The Thermocouple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
Video . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
step 3: Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
step 4: Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
Related Instructables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
Advertisements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
Customized Instructable T-shirts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
http://www.instructables.com/id/Making-A-Thermocouple/
intro: Making A Thermocouple A thermocouple is a device used to measure temperature by utilizing the Seebeck effect. This instructable will show a very simple method of making a thermocouple so you can precisely measure the internal temperature of your thanksgiving turkey. I'm sorry that the one picture I have came out terrible. The picture with the flash off was even worse (low battery syndrome). I was debating weather or not to post - but considering I couldn't find instructions anywhere on the web on how to do this, I decided to go forth and conquer. At least the video in step 2 is somewhat amusing. If I can - I'll build my own bridge and make my own meat thermometer probe. Why? you ask. Why not? What's cooler than measuring the temperature of your turkey with your trusty multimeter. And in my case, my trusty cheapo multimeter and calculator :P
step 1: Materials 1. Thermocouple wire : we got ours from http://www.omega.com/prodinfo/ThermocoupleWire.html You can probably do it with your own wires - but the must be dissimilar materials and your results may vary. If the materials are not suitable, you will know as soon as you try to calibrate. 2. A capacitor bank or other method to spot weld a tiny wire.
step 2: Actually Making The Thermocouple 1. Strip back the outer insulation 2. Strip back each individual wire and expose about .24-.5 inches of wire. 3. Bend the wire to make a contact point** 4. Weld (see next step for a suggested setup). Now you can use your thermocouple (a whole other set of instructions). We used Labview 7 a DAQ board and a conditioner board (which provided a 1/4 Wheatstone bridge).
Video
**If you have more than one contact point, you're measurement will be the average temperature over all of the contact points rather than the temperature at the contact.
http://www.instructables.com/id/Making-A-Thermocouple/
step 3: Welding We had a fancy little device that provided a ground (pliers) and a hot "plate." We would grasp wire in contact with the pliers and touch the hot plate (closing the circuit). A high amperage discharge would occur and the wire would spot weld. I suspect it was a capacitor bank. All you'd need is a sufficiently large bank of charged caps. Take a pair of insulated pliers and attach the ground wire to an exposed bit of metal. Then grasp your thermocouple wire in the pliers and touch the positive end of the charged cap bank. I would personally start small and add caps as necessary ;)
step 4: Calibration Okay, so lets say you have the tools to use your Thermocouple (I don't, but the measurements lab did). As with any other measuring device, you must form a calibration curve to show your measurements are accurate/precise and credible. Given the tools/supplies available. We made an ice water bath and a boiling water bath. Ideally, we would have added salt to the water to help it get colder. We used a normal thermometer to measure an analog temperature. Then, we started recording the thermocouple data in Labview and went from the room to the ice water bath. We saved this data and repeated for the hot water bath. As thermocouples have a linear relationship to temperature, linear interpolation can be used to determine any temperature within the thermocouples range. You can also determine the response time of the thermocouple based on the data collected.
Related Instructables
Statistical Analysis of Turkey Cooking by trebuchet03
Temperature Control For Kitchen Appliances by timothy
Weekly Project: Hottie Hoodie-Be a Walking a Weather Station by PopSci
Be a Scientist: Make your own thermometer by Kiteman
Advertisements Customized Instructable T-shirts
http://www.instructables.com/id/Making-A-Thermocouple/
3D chocolate printer made from LEGO by saul
Illustrated Turducken Recipe by kachun
Toaster Oven Reflow Soldering (BGA) by colin
Multifunction Digital Thermometer by J_Hodgie
Comments 15 comments Add Comment
android_18 says:
Nov 28, 2008. 1:27 AM REPLY
is it possible to construct a thermocouple which could produce 3 volts or higher?
royalestel says:
Jun 5, 2007. 9:06 PM REPLY
Cool! Favorited!
NachoMahma says:
Jun 1, 2007. 1:13 AM REPLY Great job! A few comments. 1) TCs are not linear, especially at the extremes of their ranges. That said, for most DIY purposes (0-100 degC) "common" (J/T/K) TCs are close enough. 2) I like to do a third calibration check at a temperature close to what I expect to measure (usually ~50% full-scale), but I'm a bit compulsive (13 yrs as an Elect/Instr Tech). 3) Make sure you use actual TC wire and not extension wire if you are concerned about absolute accuracy. Extension wire is OK if you're only worried about repeatibility. 4) I haven't looked at one in a while, but the Omega Product Handbook for Temperature Omega() was my TC Bible back in the 80s-90s.
godot01 says:
Feb 24, 2007. 10:50 PM REPLY
I guess it depends on the application but welding a thermocouple seems like overkill. We always silver solder them. We read them out thru a fluke t/c reader or a micromite. Just twisting T/C wire is generally good enough for many applications although not very durable. If this is not accurate enough for your application then a T/C is probably a bad choice anyway. We use RTDs in some applications.
0.775volts says:
Nov 30, 2006. 8:52 PM REPLY OK, you did a good job making your thermocouple (I commented on making thermocouples in that instructable that was either about spot-welding, or playing with a big-ass capicitor bank, i can't remember which). ok, the best way to explain this is to highlight the process by which a friend and I have made these before. sorry if i'm a bit stylistic grammatically, i'm not on my first beer of the evening. ok, so take your length of thermocouple wire (I prefer type t) cut the jacket off the conductors, and strip both of them approx 1/2" on one end of the thermocouple wire, twist the conductors together. connect this end to the + side of your capacitor bank/welder/bigass current source on the other end of the thermocouplewire: take the conductors and cross them right where the insulation ends. twist them together as tightly as possible and cut them after one good, tight twist. then, take something conductive and flat and connect it with a big-ass wire to the - side of your current source. get a pair of needle nose pliers, clamp them on to the thermocouple wire about an inch away from the free end. wrap a rubber band/string/hairtie/whatever around the handles of the pliers so they stay clamped on the wire. put on welding guantlets and sunglasses and charge your current source once charged, pick up the needle nose pliers and get ready to spot weld the thermocouple to spot weld, just touch the thermocouple wires to the metal plate, creating short circuit and welding the metals together. pull it away after about 1/10 of a second, ie: get a good pop and move it away and you're done. if you stick it togeter for longer, you're likely to melt something and start a fire. we've done this many times, and it produces a good thermocouple. of course, you'll need to calibrate it when you use it, but you always did that with new thermocouples anyway, right?
trebuchet03 says:
Nov 30, 2006. 9:07 PM REPLY We're required to calibrate everything every time we use it ;) Even if Tcouple, transducer, scale etc. etc. came with a calibration chart - we are required to re-do it. These thermocouples were used for an exercise in calculating time constants and comparing to soldered connections. When a thermocouple has more than one contact point (such as wrapping onto itself) your measurement will change - instead of measuring at a point - you'll be measuring the average of the connection points. For the purpose of our lab, wrapping would give inaccurate results (higher time constants). Don't get me wrong, your method works too (just not so well for our application :P).
0.775volts says:
Dec 1, 2006. 1:23 PM REPLY I'll have to send you pictures of our set up, we wrap and cut after the first wrap to have enough material to spot weld the wire, it makes a little blob that is solid, so there is only one (rather large) contact point. we had that issue with some of the first thermocouples we built, they were all over the place in terms of response. that's when we realized we needed to change our method (it took us 50' of type T wire to figure out where we were going wrong). when I'm back in my home town for the holidays, I'll duplicate the setup and take pictures so you can see what I'm talking about.
http://www.instructables.com/id/Making-A-Thermocouple/
ewilhelm says:
Nov 21, 2006. 6:14 PM REPLY
You are now required to post a time/temperature plot of your turkey!
trebuchet03 says:
Nov 23, 2006. 12:46 AM REPLY
"Just for fun" - I started writing an instructable titled: "A Statistical Analysis of Turkey Cooking." I've already come across some interesting little tidbits about turkey geometry and how they play a role in cooking time :P I think I've brought myself to a new dork low (or high?) :P
vatosupreme says:
Nov 21, 2006. 8:06 PM REPLY
Yeah, but we need the data in real time on instructables. So how about hooking it to a webserver :P
zachninme says:
Nov 23, 2006. 8:40 PM REPLY
That would be awesome! Stick in about 10 probes, and make a small AJAX site to display info, and allow us to yell at you when you should do something :-)
Oracle1729 says:
Nov 22, 2006. 2:05 AM REPLY You're putting 2 dis-similar metals into the meat. The meat will act as an electrolyte and you'll have a simple battery. The effect will be metal ions flowing from your thermocouple into the bird. Most metal ions are toxic except in tiny amounts.
trebuchet03 says:
Nov 22, 2006. 9:07 AM REPLY
It can be put in an inert carrier without changing its ability to measure temp (although it may increase response time).
Oracle1729 says:
Nov 22, 2006. 2:44 PM REPLY
Of course it can, and that's what a commercial unit does. However, this instructable shows using it directly without an inert carrier, so using it as shown here will posion the meat.
trebuchet03 says:
Nov 22, 2006. 9:36 PM REPLY
Fair Enough :) I also found out today that the wire insulation is not food service safe. Not sure why though -- maybe lead or something? So, for said time/temp plot - I got a cheap meat probe ($15) and I'll keep record :) I'll even calibrate it :P
http://www.instructables.com/id/Making-A-Thermocouple/
Related Documents
Making A Thermocouple
May 2020 2
Thermocouple
June 2020 7
Thermocouple[1]
November 2019 6
Thermocouple Thermometry 2006
June 2020 2
Thermocouple Tutorial V2b
May 2020 3