I was taught this when I was in the military, to ensure our cold-junction correction was working before using a meter to measure an external temperature. Over the past 40 years I had totally forgotten about it. Thanks for the reminder!
Yes, I should have mentioned that actually. If your meter isn't at ambient temperature internally before you take your thermocouple measurement then your reading will not be accurate. This is a way to double check that.
@@EEVblog are you sure about this? I always thought the thermocouple measures temperature difference between junctions, so whatever temperature is inside the meter shoud work as long as it's measured accurately internally.
@@kaziq Why would you need to measure ambient temperature in this case if the reading does not depend on it? As you said, thermocouples measure temperature difference between hot and cold junction and the cold junction is at ambient temperature so you have no way to know the absolute temperature without ambient reference.
@@maximgusanu5294 I didn't say you don't need to measure the ambient temperature. My point is that the temperature inside the meter does not have to be the same as the ambient temperature for the measurement to be accurate. Dave said it has to be the same, but I can't understand why. You say the cold junction is at ambient temperature, so where is the cold junction physically? If it's inside the meter, what does the ambient temperature have to do with it? You only need to know the temperature inside the meter (as close to the junction as possible) to know the cold junction temperature, no?
@@kaziq I think the cold junction is inside the thermocouple jack, not inside the meter, so the point is that the internal temperature of the meter has to be the same as the temperature of the jack.
5:01 The lag for ambient temperature issue is a good reminder that this works both ways: if you're using a thermocouple and just moved the meter to a different environment, you need to wait for the meter's temperature to equalize or the thermocouple reading will be off.
Yep, and these multiassumpters (not to be confused with multimeters) may not even have correct LUT/polynomial for temperature. Mine 838 shows over 1000C at 400C soldering fan, but it is totally accurate at 0C and 100C. That's probably because it is calibrated only by these two points
Agree. Video 5 minutes 59 seconds long. Opening with an ad about gut health and taking a big, healthy dump every morning by a Dr. Gundry. The ad was 47 minutes 55 seconds in length! At the end of the anticipated video is a very boring 11 minute 11 seconds ad scrolling the side effects of the latest immunosuppressive drug. That's a two minute 'quick tip' expanding into an unwieldy one hour, five minutes, and five seconds long video production. Yes, I checked the timer and let it run. Went through three soft fried eggs, two English Muffins with sweet butter and homemade lime marmalade. Full pot of Folgers. Guess that now I will have to watch the 'two minute tip', skipping the ads this time. Are all Australian tech tips long winded?
HVAC installer here and “retired” controls engineer. I check temps every install with a temp tool and didn’t even think to use this feature and keep the thermocouple around as either a backup or bring one less tool. Great stuff!
@@thecakeredux I kid you not, I've seen an actual product (Chinese weather station) that let's you log the temperature in radians. I guess the company was like "yeah more features, more sales".
The standard probes are a thermocouple junction whether you want them to be or not. Copper wires with plated probe tips. Fortunately the voltages produced are small.
Now for the most important question, Dave? Just how many multimeters DO you have??? A guy with one meter knows what the temperature is; a guy with 2 or 3 or 7 or 8 is never sure.....
I just tried it out on a UNI-T UT139C and it works! I also tried it out on a pocket multi meter ANENG AN 8009 and I didn't even have to short the leads out. I sprayed both of them with a can of compressed air and it actually picked it up. This is something I'll remember for life and a little trick I'll show people who didn't even know about it. I always wondered why I did that and I never clocked on n thought there was something weird or wrong going on with the meter. But now I know 👍🏻 Thanks once again Dave for all of your tips 🙂
Clever. I check the fuse in the meter by setting the buzzer and put the probe in the mA test socket. When the fuse is in working order it will go through the mA jack to COM.
A few month's back I shorted the leads while changing modes on your BM235 meter. Passed through the temperature mode and was shocked to see it reading the ambient temperature. At the time, I assumed it was just some internal zero reference that happened to coincide with the ambient temp. Cool to know it actually is reading a thermo couple! I shall remember this trick.
Thanks. For same reason after you charge you keysight accu using the stock charger you have to wait for the multimeter board to cool down before you can do accurate thermocouple measurents. When charging the accu and the board can easily go to 35-40*C and so does the reference sensor. Fortunately for this type, you can judge by temporarily incorrect ambient temp indication.
Thanks for the tip mate. I knew how this all worked but I would never have thought to short the leads to get an ambient temperature reading. That's bloody brilliant! Honestly I feel a little dumb for not having thought of it myself. Live and learn right? Works on my Fluke 179.
Wow I've just gone to the radio shack to grab my multimeter to try this cool trick and it works. I've been using My multimeter for years and never knew that.
How much I love you and I love your channel. I wish you lasting success ... I am an Arab from Iraq and weak in the English language. I hope you will support the Arabic translation 
The global world of business and technology runs on english as a standard. It might be a good idea to start learning english so you can read the words on schematics and data sheets without the errors that computer translation makes, and freely communicate with other techies around the globe.
@@jenniferwhitewolf3784 Yes, I am struggling to learn the English language, either because I translate the Google translation from Arabic text into English, and vice versa
My automotive collage taught me "OL" Does not mean Overload, it stands for "out of limit" 25 years later I find my Fluke manual on line and it states "OL" stands for "Over-load" I'm glad I only remember incorrectly correcting one person...
No way! I never new you could do that. I have a Fluke 87-5 and tried it out and what do you know... it worked! 68.8F. How cool is that! Thanks for sharing this tip!
I've been doing this for years. I thought it was very common knowledge. That being said like you mentioned in the video it is never in the manuals so folks might not be in the know. However on the plus side.. Once you know you know.
4:25 You have been holding those leads for a while and transferred some heat to them, maybe conductivity of the metal changed slightly due the heat increase so it shows increased temp?
I become really interested in electronics in 2009. I came across Eev. I never knew Dave had just started channel. So 12 years or so I've been watching the "Crazy Austrian Guy"! 🤣🤣 Joke ?? I know he's from Austrailia. Anyway he's been in my top 3 ever since....love it
Never had a temp probe for my Fluke 179. Got it from my old job, and it's been one of the best meters I ever had, just never used the temp portion as I don't have the attachment. The more I know!
I use a cheap hakko clone soldering tester occasionally for the same purpose. It's just a thermocouple in a box with a readout you can put the tip of your iron on to check it's running the right temperatures.
Wow, this even works with my cheap-ass, no-brand multimeter! I don't even need to short the leads for it to work. And its reading really matches ambient!
Personally, I think a discussion about the deficiencies of a DVM/VOM as compared to an 11 Megohm or 100 Megohm VTVM or equivalent solid state design might me in order. The HP-410B was the Gold Standard in my day!
Might not but I see there are other techtronix stuff that do: uploads.tapatalk-cdn.com/20161113/ee1a2518e0fed6b99c2fb28a87875628.jpg Someone brought one that does on the Eevblog: www.eevblog.com/forum/blog/eevblog-712-uni-t-ut71e-multimeter-(why-uni-t-meters-suck)/msg604683/#msg604683
had to check the date this was released, while at the start of the video very interesting! I dont know how thermocouples work; I'll have to watch your video
Ok I read the title wrong, I thought you could use one without a temperature feature to do temperature, kind of like how you can use a multimeter with a light meter (e.g. Apogee) and using a conversion factor get the actual light output.
15 years in HVAC and I'm ashamed I didn't realize this. I knew there was an ambient sensor in them for the offset, had no idea I could make it display that temp with a simple short. I have stormed out of walk-ins because I didn't have my K-probe or it broke because there's no such thing as a good K-probe.
Doesn't work with mine for some reason. Dunno. But it's a cheapo one and it doesn't even work with the temperature reader setting anyway. I put it outside for 10 minutes, and it still showed 22-26 degrees, same as inside. Cool video though, I never knew this.
I always hated thermocouples because they are so inaccurate and drift with time and usage. My first assignment as an electronic engineer was to replace the 10 thermocouples in the instrument from thermocouples to RTDs (Resistance Temperature Detector). They use a platinum wire wound around a ceramic core. The resistance of the wire will change with temperature. The initial resistance is usually 138.5 ohms at 100°C. There are many types of RTDs but this is the most common. With advanced math, solving a 9 variable matrix and 3 simultaneous equations I was able to reduce the circuitry to 1 common op-amp and 4 precision resistors for an accuracy of 0.1% over a range from -200°C to +600°C and a voltage output of 5mv/°C from -1V to +3V. I was also able to correct for any length lead resistance to so only a 2 wire RTD is necessary. My boss was so shocked and excited he didn't wait for the lawyers in the patent department to do their jobs and immediately put my design into production. The patent lawyers came back and said they can't patent the design now because it is already in production and is now considered common knowledge! There went my patent stipend of $300 from my company. LOL
My BSIDE ADM66 multimeter gives me the temperature as soon as I set it to the temperature setting. I had never played with this setting before. I have another multimeter and I'm now curious to see if it also works in the same way. Thanks Dave.
Instructions not clear enough. I've got my EEVBlog 121GW Multimeter stuck up my arse now. I'm off to A&E. Do you think my meter will still be in calibration after the nurses and doctors retrieve it?
I got one of the better Brymen multimeters since few years, but sadly it didn't have temperature reading... I had to buy a specialized temperature reader :/
Just note that some cheap-arse meters do not have cold junction compensation and just assume an average room temp of 25 degrees C. They'll just always measure 25 degrees C when shorted, no matter if ambient is cold or warm.
I think I've seen some very cheap DMM (9205A or 830 series DMM) with "temperature" measurement. I don't think they have proper internal temperature sensor, they're just fixed offset voltage coupled with onboard LM358 dual op-amp to amplify those 41uV/C into something temperature reading. I suppose they're just offset it to standard normal room temperature from factory. I'll try to heat it up one day to test it, the meter is super cheap though, less that $10 shipped. My Texio DL-2060 (IIRC) 6 1/2 digit bench DMM will do temperature measurement with proper temperature probe adapter, i suppose they provide that relative room temperature measurement inside those adapter then compare it to the readings from plugged thermocouple/sensor, the meter does allow you to set whatever temperature offset that you want though (probably similar to REL function if you don't have the proper adapter).
That's actually pretty freaky-deaky. Too bad only my multimeter doesn't have a temperature function but I'll keep this in mind for future upgrading. ;)
In my opinion, this feature is not useful, though mildly interesting for illustration purposes, I suppose. You demonstrated though your multiple example meters that this internal temperature measurement is only about +/-2degC at best. I can determine the ambient temperature (within a reasonable range, say 15-28degC) with that same uncertainty without any meter, and my estimates don't suffer from lag either.
I have a multimeter that came with a temp probe. I got it stuck out the window and I just turn the meter on when I want to know the temperature outside.
I’ve noticed this effect before however I always thought it had something to do with the contact between the two probes doing some magic, now that you mention the cold junction temperature compensation it all makes sense! However, I’ve just tried it on a Keithley DMM6500 bench DMM and it reports 22.80 °C (5 °C lower than ambient) right after power on, leaving it for a couple minutes to warm up shows no difference despite it clearly warming up on my thermal camera. I get the same results using either shorted probes or a proper ¾” shorting jumper? I pulled up the calibration report and it was calibrated at 22.2 °C, maybe the cold junction temperature is hardcoded or something but that wouldn't make sense? Edit: Just tried it with my old pile of garbage DIGITECH QM1323 and says 25.4 °C which is only 2 °C off but it does respond to temperature changes (very slowly).
Interesting, Will have to try my bench meters and maybe put them in the thermal chamber. There are different methods for doing the compensation, so could be something interesting happening here.
@@EEVblog I've just had a look through the manual for the DMM6500 as I don't use it for temperature measurements and it says the "Thermocouple Reference Junction" is 'simulated', I now see I can go into the UI and it's set to 23 °C! Changing it to anything else changes the shorted reading to that. It appears you can attach an external reference junction as part of the SCAN accessory cards.
@@WizardTim Wow, had no idea! But thinking about it, it makes sense, as rack mount gear can heat up, so an internal temp sensor isn't going to be at ambient temp for that absolute reference.
@@EEVblog This might make a good trap for young players video (or maybe as an addendum to this video?) as the K type thermocouples I have I always thought were bad because they measured way off on what I thought was the best tool I had for utilizing thermocouples! Turns out they’re all spot on!
My Voltcraft meter does not seem to do this. It does have a temp function on the dial. Not that I need it. I have oodles of DHT22 sensors kicking around.
Nice one Dave! My Aneng AN8009 mesures it even without shorting the leads, afer a second of 0000. And indeed if you cool the multimeter down in the fridge, the thermocouple leads don't show the real ambient temperature anymore, it is suddenly same as internal, or thereabouts. Nice trick!
As a kid, I partnered with a guy who would solder mod chips into consoles. Two of us working meant we could mod twice the amount of consoles & we made a killing! Sometimes I'd watch him work, he was about 45 and would use an analogue multimeter, he said he'd bet his life on it being more accurate for everything and wouldn't let me touch the thing. I used a trusty UNI-T digital multimeter. Anybody prove/disprove his claim? Looked online & couldn't find an analogue meter today..
So, do the ones with the internal temp sensor that will display it, is that also a thermocouple type sensor, *or* is that some other type of sensor? Do the internal temp sensors need a sensor for the temp correction, or do they just assume it's room temp?
Most of them use a small thermistor to measure the internal temperature. It's basically a resistor whose resistance will change based on the temperature.
Well, now I know that if I ever buy a multi-meter with a Temp Setting, I can use this trick, but until then, I suppose I will just make my own thermometer. (hah..more fun that way anyhow)
"Just a quick, 2 minute tech tip!" _Looks at video length..._ Now that Dave figured out how to deal with a multimeter with no temp probe, he needs to figure out how to deal with a multimeter with no watch :)
For the difference between 2 and 6 minutes, measuring the voltage across a capacitor connected to a current source might work. More as a joke than a practical timer as for good accuracy over a significant time one would need maybe better than average components.
They can only measure temperature difference between two junctions. To know the absolute temperature at one junction, you need to know the absolute temperature of the other junction. By the way thermocouples output voltage instead of resistance.
@@chuanliu4685 Yes I must have been confused with the method of reading temperature with certain alloys based on how the resistance changes with temperatures. Also known as resistance thermometers.
I just noticed that my multimeter has this thermocouple temperature thingy. What is the purpose of it? Why would you need to measure temperature with a multimeter?
I was taught this when I was in the military, to ensure our cold-junction correction was working before using a meter to measure an external temperature. Over the past 40 years I had totally forgotten about it. Thanks for the reminder!
Yes, I should have mentioned that actually. If your meter isn't at ambient temperature internally before you take your thermocouple measurement then your reading will not be accurate. This is a way to double check that.
@@EEVblog are you sure about this? I always thought the thermocouple measures temperature difference between junctions, so whatever temperature is inside the meter shoud work as long as it's measured accurately internally.
@@kaziq Why would you need to measure ambient temperature in this case if the reading does not depend on it? As you said, thermocouples measure temperature difference between hot and cold junction and the cold junction is at ambient temperature so you have no way to know the absolute temperature without ambient reference.
@@maximgusanu5294 I didn't say you don't need to measure the ambient temperature. My point is that the temperature inside the meter does not have to be the same as the ambient temperature for the measurement to be accurate. Dave said it has to be the same, but I can't understand why.
You say the cold junction is at ambient temperature, so where is the cold junction physically? If it's inside the meter, what does the ambient temperature have to do with it? You only need to know the temperature inside the meter (as close to the junction as possible) to know the cold junction temperature, no?
@@kaziq I think the cold junction is inside the thermocouple jack, not inside the meter, so the point is that the internal temperature of the meter has to be the same as the temperature of the jack.
5:01 The lag for ambient temperature issue is a good reminder that this works both ways: if you're using a thermocouple and just moved the meter to a different environment, you need to wait for the meter's temperature to equalize or the thermocouple reading will be off.
Yes, mentioned in my pinned comment above.
It took me a while to realize that this wasn’t actually a late April fools video. Super cool and thanks for sharing!
Have met some ultra cheap ones which do not have that, and simply have a 25C offset for temperature measurement.
Yep, and these multiassumpters (not to be confused with multimeters) may not even have correct LUT/polynomial for temperature. Mine 838 shows over 1000C at 400C soldering fan, but it is totally accurate at 0C and 100C. That's probably because it is calibrated only by these two points
Australian time warp - two minute tech tip is almost 6 minutes long over here ! ha ha
Time dialation caused by the earths spin.
@@EEVblog Next video: No timer on your multimeter?
Agree. Video 5 minutes 59 seconds long. Opening with an ad about gut health and taking a big, healthy dump every morning by a Dr. Gundry. The ad was 47 minutes 55 seconds in length! At the end of the anticipated video is a very boring 11 minute 11 seconds ad scrolling the side effects of the latest immunosuppressive drug. That's a two minute 'quick tip' expanding into an unwieldy one hour, five minutes, and five seconds long video production. Yes, I checked the timer and let it run. Went through three soft fried eggs, two English Muffins with sweet butter and homemade lime marmalade. Full pot of Folgers. Guess that now I will have to watch the 'two minute tip', skipping the ads this time. Are all Australian tech tips long winded?
Looks like all of your meters are too long. Try Imperial.
HVAC installer here and “retired” controls engineer. I check temps every install with a temp tool and didn’t even think to use this feature and keep the thermocouple around as either a backup or bring one less tool. Great stuff!
I put my multimeter in the microwave to see if it really measures ambient temperature, something went wrong!
Probably left it on RAD when you wanted DEG - happens to me all the time!
@@thecakeredux I kid you not, I've seen an actual product (Chinese weather station) that let's you log the temperature in radians. I guess the company was like "yeah more features, more sales".
@@webkar I can only imagine that's a translation error, right? RIGHT?
Your multimeter melt
Did you try it using the Popcorn button???
I'm willing to bet that Dave has the biggest multimeter collection in Australia.
Now you got me thinking
Multi-multimeter
You may be right ...
And my wife thinks I'm crazy for having 4 😂
The standard probes are a thermocouple junction whether you want them to be or not. Copper wires with plated probe tips. Fortunately the voltages produced are small.
Yes, i explain this in my tutorial video.
Now for the most important question, Dave? Just how many multimeters DO you have??? A guy with one meter knows what the temperature is; a guy with 2 or 3 or 7 or 8 is never sure.....
The same logic can be applied to a clock maker. Never knows what time it is.
Nice one Dave, cool tip
Or should I say "ambient tip" ??
Just the tip please.
Or that's what she said.
@@EEVblog Blighmey Dave good thing the wifey isn't reading the comments or she'd be waiting for you like a dropbear in a tree out in the parking lot!
Immediately reaches for a meter. Oooh yeah, it only bloody works. Thanks Dave 👍
wow! you blowed my mind, used multimeters for 15 years and didn't know this trick
I just tried it out on a UNI-T UT139C and it works! I also tried it out on a pocket multi meter ANENG AN 8009 and I didn't even have to short the leads out. I sprayed both of them with a can of compressed air and it actually picked it up.
This is something I'll remember for life and a little trick I'll show people who didn't even know about it.
I always wondered why I did that and I never clocked on n thought there was something weird or wrong going on with the meter. But now I know 👍🏻
Thanks once again Dave for all of your tips 🙂
When can we expect the opening of your multimeter museum?
Just tried it on my BM235, boom it works! Fascinating.
Clever. I check the fuse in the meter by setting the buzzer and put the probe in the mA test socket. When the fuse is in working order it will go through the mA jack to COM.
A few month's back I shorted the leads while changing modes on your BM235 meter. Passed through the temperature mode and was shocked to see it reading the ambient temperature. At the time, I assumed it was just some internal zero reference that happened to coincide with the ambient temp. Cool to know it actually is reading a thermo couple! I shall remember this trick.
this is a real nice trick for those that have multimeters that use that dinky little insert module.
appreciate the tip!
Thanks. For same reason after you charge you keysight accu using the stock charger you have to wait for the multimeter board to cool down before you can do accurate thermocouple measurents. When charging the accu and the board can easily go to 35-40*C and so does the reference sensor. Fortunately for this type, you can judge by temporarily incorrect ambient temp indication.
Thanks for the tip mate. I knew how this all worked but I would never have thought to short the leads to get an ambient temperature reading. That's bloody brilliant! Honestly I feel a little dumb for not having thought of it myself. Live and learn right? Works on my Fluke 179.
I've known this trick, but I didn't know why it works. Thanks!
Wow I've just gone to the radio shack to grab my multimeter to try this cool trick and it works. I've been using My multimeter for years and never knew that.
How much I love you and I love your channel. I wish you lasting success ... I am an Arab from Iraq and weak in the English language. I hope you will support the Arabic translation

The global world of business and technology runs on english as a standard. It might be a good idea to start learning english so you can read the words on schematics and data sheets without the errors that computer translation makes, and freely communicate with other techies around the globe.
@@jenniferwhitewolf3784
Yes, I am struggling to learn the English language, either because I translate the Google translation from Arabic text into English, and vice versa
Wow, I never knew this. Brilliant.
thank you this is really handy, just tried it and it works, now I can at least measure ambient, since I dont have a probe for my meter
My automotive collage taught me "OL" Does not mean Overload, it stands for "out of limit"
25 years later I find my Fluke manual on line and it states "OL" stands for "Over-load"
I'm glad I only remember incorrectly correcting one person...
That was just a fluke, the real answer is "Out of Limits"
@@Bob_Adkins
Fluke website: User Manuals
79/29 Series II | Users manual
02/2018 | Users manual
Page 15 of 47 "OL" = OVERLOAD
After you explained what do you want to achieve, I immediately said "just short the sockets". Nice trick!
Same here. Known about this for years.
No way! I never new you could do that. I have a Fluke 87-5 and tried it out and what do you know... it worked! 68.8F. How cool is that! Thanks for sharing this tip!
Cool tip Dave, thank you
That's an "ambient tip" not cool.
@@SAHILKHAN-lu8oq lol, I seem to be warming up to that comment
And that works ! Incredible
Nice - works perfect on my UNI-T UT61B. Thanks for the hint and greetings from Germany :-)
great trick! never thought of it before even though i use thermocouples often
Nice tip, I wondered why I saw that happen on my meter.
I've been doing this for years. I thought it was very common knowledge. That being said like you mentioned in the video it is never in the manuals so folks might not be in the know. However on the plus side.. Once you know you know.
0:38 I work in biochemistry and we use Agilent instruments for our scientific work. Pretty good products.
Excited for this new series.
4:25 You have been holding those leads for a while and transferred some heat to them, maybe conductivity of the metal changed slightly due the heat increase so it shows increased temp?
I become really interested in electronics in 2009.
I came across Eev. I never knew Dave had just started channel.
So 12 years or so I've been watching the "Crazy Austrian Guy"! 🤣🤣
Joke ?? I know he's from Austrailia.
Anyway he's been in my top 3 ever since....love it
Never had a temp probe for my Fluke 179. Got it from my old job, and it's been one of the best meters I ever had, just never used the temp portion as I don't have the attachment. The more I know!
I use a cheap hakko clone soldering tester occasionally for the same purpose. It's just a thermocouple in a box with a readout you can put the tip of your iron on to check it's running the right temperatures.
Wow, this even works with my cheap-ass, no-brand multimeter! I don't even need to short the leads for it to work.
And its reading really matches ambient!
Personally, I think a discussion about the deficiencies of a DVM/VOM as compared to an 11 Megohm or 100 Megohm VTVM or equivalent solid state design might me in order. The HP-410B was the Gold Standard in my day!
4:08 Does that read under the sticker of the Tektronix DMM916 Australian Defence Force?
Noticed the same thing lol
Maybe that's military surplus.
The text "Australia" won't fit there
Might not but I see there are other techtronix stuff that do: uploads.tapatalk-cdn.com/20161113/ee1a2518e0fed6b99c2fb28a87875628.jpg Someone brought one that does on the Eevblog: www.eevblog.com/forum/blog/eevblog-712-uni-t-ut71e-multimeter-(why-uni-t-meters-suck)/msg604683/#msg604683
my mind has been blown
had to check the date this was released, while at the start of the video
very interesting! I dont know how thermocouples work; I'll have to watch your video
Ok I read the title wrong, I thought you could use one without a temperature feature to do temperature, kind of like how you can use a multimeter with a light meter (e.g. Apogee) and using a conversion factor get the actual light output.
15 years in HVAC and I'm ashamed I didn't realize this. I knew there was an ambient sensor in them for the offset, had no idea I could make it display that temp with a simple short. I have stormed out of walk-ins because I didn't have my K-probe or it broke because there's no such thing as a good K-probe.
Doesn't work with mine for some reason. Dunno. But it's a cheapo one and it doesn't even work with the temperature reader setting anyway. I put it outside for 10 minutes, and it still showed 22-26 degrees, same as inside. Cool video though, I never knew this.
I can’t wait to get to work next and ask the instrument technicians if they can quickly tell me how warm the inside of their multimeter is.
Wow, learn something new everyday! Thanks!
I have victor vc97.it changed a little bit when i light fire under my prop.not show corecly.but that was nice info tnx
"2 minute tech tipp video"
~ looks down at video length.
~ Starts questioning the own perception of time.
~ Panic
I always hated thermocouples because they are so inaccurate and drift with time and usage. My first assignment as an electronic engineer was to replace the 10 thermocouples in the instrument from thermocouples to RTDs (Resistance Temperature Detector). They use a platinum wire wound around a ceramic core. The resistance of the wire will change with temperature. The initial resistance is usually 138.5 ohms at 100°C. There are many types of RTDs but this is the most common. With advanced math, solving a 9 variable matrix and 3 simultaneous equations I was able to reduce the circuitry to 1 common op-amp and 4 precision resistors for an accuracy of 0.1% over a range from -200°C to +600°C and a voltage output of 5mv/°C from -1V to +3V. I was also able to correct for any length lead resistance to so only a 2 wire RTD is necessary. My boss was so shocked and excited he didn't wait for the lawyers in the patent department to do their jobs and immediately put my design into production. The patent lawyers came back and said they can't patent the design now because it is already in production and is now considered common knowledge! There went my patent stipend of $300 from my company. LOL
Some DMMs you don't need even probes, they show the temperature directly.
“This one is reading a bit high don’t why” lol seriously!!!!! 😂
This is so cool, I didn't know that :-) Tried it on my multimeter and it also works
Yeahp, I do it everytime so that I don't have to always be connecting and disconecting those TCs just to measure the ambient temp.
My BSIDE ADM66 multimeter gives me the temperature as soon as I set it to the temperature setting. I had never played with this setting before. I have another multimeter and I'm now curious to see if it also works in the same way. Thanks Dave.
Instructions not clear enough.
I've got my EEVBlog 121GW Multimeter stuck up my arse now.
I'm off to A&E. Do you think my meter will still be in calibration after the nurses and doctors retrieve it?
I got one of the better Brymen multimeters since few years, but sadly it didn't have temperature reading... I had to buy a specialized temperature reader :/
Internal temperature plus zero. Excellent!
Just note that some cheap-arse meters do not have cold junction compensation and just assume an average room temp of 25 degrees C. They'll just always measure 25 degrees C when shorted, no matter if ambient is cold or warm.
I think I've seen some very cheap DMM (9205A or 830 series DMM) with "temperature" measurement.
I don't think they have proper internal temperature sensor, they're just fixed offset voltage coupled with onboard LM358 dual op-amp to amplify those 41uV/C into something temperature reading.
I suppose they're just offset it to standard normal room temperature from factory.
I'll try to heat it up one day to test it, the meter is super cheap though, less that $10 shipped.
My Texio DL-2060 (IIRC) 6 1/2 digit bench DMM will do temperature measurement with proper temperature probe adapter, i suppose they provide that relative room temperature measurement inside those adapter then compare it to the readings from plugged thermocouple/sensor, the meter does allow you to set whatever temperature offset that you want though (probably similar to REL function if you don't have the proper adapter).
tried it on my keysight u1251b. it told me it's time for a beer.
Dave: Quick two minute video
RUclips: 5 min 59 secs
I'm gonna use this
That's actually pretty freaky-deaky.
Too bad only my multimeter doesn't have a temperature function but I'll keep this in mind for future upgrading. ;)
In my opinion, this feature is not useful, though mildly interesting for illustration purposes, I suppose. You demonstrated though your multiple example meters that this internal temperature measurement is only about +/-2degC at best. I can determine the ambient temperature (within a reasonable range, say 15-28degC) with that same uncertainty without any meter, and my estimates don't suffer from lag either.
In the next video Dave is going to show us how to use a baby thermometer to measure voltage
Too cool thank you Dave!
Damn I definitely need a new multimeter, still rocking my old cheap-ass Maplin one I bought nearly a decade ago with pocket money.
Update, I got one! A brand new EEVblog BM235, barely taken it out of the box and already super happy with it.
Mine has a totally separate plug for the temp probe but I am still gonna try it. :-)
Nice follow-up from the other channel ;)
Doesn't work on my Fluke 25.
I have a multimeter that came with a temp probe. I got it stuck out the window and I just turn the meter on when I want to know the temperature outside.
I’ve noticed this effect before however I always thought it had something to do with the contact between the two probes doing some magic, now that you mention the cold junction temperature compensation it all makes sense!
However, I’ve just tried it on a Keithley DMM6500 bench DMM and it reports 22.80 °C (5 °C lower than ambient) right after power on, leaving it for a couple minutes to warm up shows no difference despite it clearly warming up on my thermal camera. I get the same results using either shorted probes or a proper ¾” shorting jumper?
I pulled up the calibration report and it was calibrated at 22.2 °C, maybe the cold junction temperature is hardcoded or something but that wouldn't make sense?
Edit: Just tried it with my old pile of garbage DIGITECH QM1323 and says 25.4 °C which is only 2 °C off but it does respond to temperature changes (very slowly).
Interesting, Will have to try my bench meters and maybe put them in the thermal chamber.
There are different methods for doing the compensation, so could be something interesting happening here.
@@EEVblog I've just had a look through the manual for the DMM6500 as I don't use it for temperature measurements and it says the "Thermocouple Reference Junction" is 'simulated', I now see I can go into the UI and it's set to 23 °C! Changing it to anything else changes the shorted reading to that. It appears you can attach an external reference junction as part of the SCAN accessory cards.
@@WizardTim Wow, had no idea! But thinking about it, it makes sense, as rack mount gear can heat up, so an internal temp sensor isn't going to be at ambient temp for that absolute reference.
@@EEVblog This might make a good trap for young players video (or maybe as an addendum to this video?) as the K type thermocouples I have I always thought were bad because they measured way off on what I thought was the best tool I had for utilizing thermocouples! Turns out they’re all spot on!
This doesn't work on mine, It always gives the same reading range, always between 24c and 25c, regardless of the ambient temperature.
My Voltcraft meter does not seem to do this. It does have a temp function on the dial. Not that I need it. I have oodles of DHT22 sensors kicking around.
Great, it's really working 😁👍
2:52 but it have to be two dissimilar metals to work but both probs are similar so how it can works ?
Use an RTD.
A PT 100 sensor will read 100ohms at Zero degrees
good to know thank you 👍
Nice one Dave!
My Aneng AN8009 mesures it even without shorting the leads, afer a second of 0000.
And indeed if you cool the multimeter down in the fridge, the thermocouple leads don't show the real ambient temperature anymore, it is suddenly same as internal, or thereabouts. Nice trick!
With handheld Infrared Thermometers selling around $10US (including batteries), multimeter temp measure is sadly obsolete. Nice tip though.
I use that in a pitch once.
How he he’ll are you getting 24.5 in autumn?
Hmm my brymen bm867 doed not seem to have this.
Pretty neat, thanks!
As a kid, I partnered with a guy who would solder mod chips into consoles. Two of us working meant we could mod twice the amount of consoles & we made a killing! Sometimes I'd watch him work, he was about 45 and would use an analogue multimeter, he said he'd bet his life on it being more accurate for everything and wouldn't let me touch the thing. I used a trusty UNI-T digital multimeter. Anybody prove/disprove his claim? Looked online & couldn't find an analogue meter today..
May keysight 1232A model not work temperature when i short the testprobe
It's there any way of calibrating the internal temperature sensor?
So, do the ones with the internal temp sensor that will display it, is that also a thermocouple type sensor, *or* is that some other type of sensor? Do the internal temp sensors need a sensor for the temp correction, or do they just assume it's room temp?
Most of them use a small thermistor to measure the internal temperature. It's basically a resistor whose resistance will change based on the temperature.
Well, now I know that if I ever buy a multi-meter with a Temp Setting, I can use this trick, but until then, I suppose I will just make my own thermometer. (hah..more fun that way anyhow)
"Just a quick, 2 minute tech tip!"
_Looks at video length..._
Now that Dave figured out how to deal with a multimeter with no temp probe, he needs to figure out how to deal with a multimeter with no watch :)
For the difference between 2 and 6 minutes, measuring the voltage across a capacitor connected to a current source might work. More as a joke than a practical timer as for good accuracy over a significant time one would need maybe better than average components.
If the resistance of the thermocouple was a -exact- known value how couldn't a temperature reading be given and how accurate could it be?
They can only measure temperature difference between two junctions. To know the absolute temperature at one junction, you need to know the absolute temperature of the other junction. By the way thermocouples output voltage instead of resistance.
@@chuanliu4685 Yes I must have been confused with the method of reading temperature with certain alloys based on how the resistance changes with temperatures. Also known as resistance thermometers.
Doesn't work on my extech dmm since it has a dedicated k thermocouple connector
I just noticed that my multimeter has this thermocouple temperature thingy. What is the purpose of it? Why would you need to measure temperature with a multimeter?
Typical for Dave: 2 minute video which lasts for 6 minutes
Cool. Thoug im bumed the Tek meter was a little off. Thats my meter had it like forever now.