Are you planning to buy a multimeter and need help? Here are some timps
How to Buy a Multimeter covers what you need to know to select a meter for DIY electronics. It focuses on the needs for audio electronics, but it’s purposely kept general in nature.
Handheld Digital Multimeters are mainly used to measure resistance, as well as DC/AC voltage and current. Common multimeters can be divided into two types, desktop and handheld digital multimeters depending on their sizes. A handheld digital multimeter is basically composed of Analogue Front End (AFE), MCU, Human-machine interface and Power supply. The design of handheld multimeters should focus on the features of low power, high performance and compact size.
Look for these features when buying a multimeter article tells that multimeters can be handy for troubleshooting PC power problems (I would say it is a must have). But the range of features and prices can be confusing when you’re shopping for one. Before you waste time and money, find out which features are essential and which are merely nice to have.
EEVblog #75 – Digital Multimeter Buying Guide for Beginners
EEVblog #91 – $50 Multimeter Shootout – Extech EX330, Amprobe AM220, Elenco, Vichy VC99, GS Pro-50
$50 Multimeter Comparison and Teardown article tells about a very nice video series on multimeters. Here is maybe the most interesting video from it:
$50 Multimeter Shootout – Part 7 – 15 DMMs Compared! – Teardowns – #0074
121 Comments
Tomi Engdahl says:
Can a multimeter shock you?
Shock hazards can occur if the meter and test leads are not properly maintained. Arc flash can occur if the meter is not properly rated for the voltage, the meter is exposed to transient voltages outside of its operating conditions, or because of defective parts or components.
https://leafelectricalsafety.com/blog/digital-multimeter-danger
Tomi Engdahl says:
Best Safety Tips For Using a Multimeter
Tip 1: Choose the Right Meter.
Tip 2: Examine The Meter Before Using It.
Tip 3: Examine The Test Probes.
Tip 5: Understand The Dangers.
Tip 6: Know the CAT Ratings.
Tip 7: Know The Voltage Ratings.
https://medium.com/@multimeterpro/how-to-use-multimeter-safely-3fe4bd418ce9
Tomi Engdahl says:
Inside a cheap multi-voltage tester (with schematic)
https://www.youtube.com/watch?v=JSLHxKM-kpw
If I had to have a single test tool for electrical maintenance work it would be a voltage tester (test lamp) as they are the best way to check for the presence of voltage reliably by applying a load to the circuit being tested.
Normally I’d suggest a Fluke tester for professional work, but for home use by DIYers or trades that might not use them so much, I’d suggest a cheap and simple set like these.
The cheap sets actually have a big advantage over the higher profile brands in that they often power themselves directly from the circuit, and in doing so load it down enough to shunt stray capacitively coupled leakage current that can cause false readings on some more sophisticated and expensive testers. It also means you don’t have to worry about batteries going flat or leaking and destroying the tester.
That does also mean that these pass enough current to give a strong shock if you hold the end of a probe while sticking the other into a live connection. Use them with suitable caution.
The circuitry in this unit is quite sophisticated, but does lack the reassurance of a fuse. As such I’d only recommend its use on lower energy circuits like home circuits beyond the distribution board, and not in high current industrial equipment. Use a Fluke for the industrial stuff to “tick the box”.
If one of the four rectifier diodes failed in this tester it could cause a high current fault with nothing but the tracks as fuses, and that might not deal with the fault as well as a proper HRC fuse.
The diodes could also have been spaced a little further apart, as the DC side does have full mains potential across it.
The tester does come with tip covers (which you will lose) but does not have shrouds around the probes so only the tips are exposed. I’d suggest adding a bit of sleeving if using in areas where you could bridge onto adjacent grounded metal or other connections.
Tomi Engdahl says:
eevBLAB 87 – Flake Multimeter Watch!
https://www.youtube.com/watch?v=YxyW_mttnQ0
Shut up and take my money!
A look at the Flake Multimeter Watch concept art by Alexander Schmid
Fluke should hire this guy!
FLAKE True RMS Multimeter Watch
https://www.youtube.com/watch?v=7zVlCvV662o
This is a demonstration of the quality and creativity of my work as a 3D artist. The combination of a measuring instrument with a comfortable to wear watch. Knowing the time while measuring some voltage may be essential in some situations…
Do you want to present your imaginary product? Contact me for more information.
Tomi Engdahl says:
Some cheap multimeters use bad old fashioned AC measurement circuits that does not measure just AC part, but also takes into account DC (with wrong scaling factor).
https://edadocs.software.keysight.com/kkbopen/digital-multimeter-ac-measurement-considerations-589742414.html
Tomi Engdahl says:
Digital Multimeter AC Measurement Considerations
https://edadocs.software.keysight.com/kkbopen/digital-multimeter-ac-measurement-considerations-589742414.html
Tomi Engdahl says:
Lopeta tämän yleismittarin käyttö heti: ”Voi johtaa vakavaan ruumiinvammaan tai jopa kuolemaan” https://www.is.fi/digitoday/art-2000009464280.html
SÄHKÖTEKNIIKAN laitteita valmistava Fluke Corporation vetää takaisin Amprobe-tuotemerkin yleismittareita. Yhtiö julkaisi tiedotteen (pdf) takaisinvedosta, ja asiasta uutisoi myös Turvallisuus- ja kemikaalivirasto Tukes.
Vika koskee seuraavia malleja:
AM-500-EUR
AM-500-EUR KIT
AM-510-EUR
AM-510-EUR KIT
HEX60-DTakaisinvedon piirissä ovat sarjanumerot välillä 535900001–587799999 ja mikä tahansa muu sarjanumero, joka alkaa muulla kuin numerolla 5. Jos sarjanumero puuttuu tai siitä ei saa selvää, laite kuuluu takaisinvedon piiriin.
Tomi Engdahl says:
Sähköiskun vaara: Onko sinulla tämä yleismittari? https://www.is.fi/digitoday/art-2000008617978.html
SÄHKÖTEKNIIKAN laitteita valmistava Fluke Corporation varoittaa Fluke 8X V -sarjan digitaalisista yleismittareistaan. Niissä on mahdollinen turvaongelma, joka voi pahimmillaan altistaa sähköiskulle.
Tomi Engdahl says:
How to use your trashy meter without blowing it up (much)
https://www.youtube.com/watch?v=-QDW0LRQVrY
Your first multimeter can initially seem a bit daunting with all the modes, but the only way to learn is to get one and play with it. I damaged my first meter when I was young by using it on the incorrect range. You can damage these cheap meters, but at the cost you don’t have to worry about it too much.
I probably made this video too long and complicated, but it’s useful to know how things work as well as how to use them.
The very cheap meters sold for around 5 $/£/€ are usually pretty accurate for their cost and very usable. Once you’ve mastered using one you can move up to something with more features or more suitable for industrial work. These cheap meters are NOT suitable for poking around in distribution boards or industrial equipment with high fault current.
Meters have a category rating as follows:-
Cat I – electronic use (these cheap meters)
Cat II – electrical appliance, but not fixed wiring or distribution boards
Cat III – general electrical maintenance in panels and machines
Cat IV – utility level work with very high fault currents
For industrial work I recommend Fluke as it appeases the clipboard warriors. There are many other brands suited to industrial use too. Beware cheap meters with fake category ratings.
The Fluke meter in the video is an original American made unit, and was my first ever real industrial meter. It cost a lot, but has lasted well.
I recommend getting these meters from a prominent supplier in your country to ensure they comply with local regulations. The one I demonstrated is from CPC/Farnell and definitely better quality than the eBay imports.
Tomi Engdahl says:
https://hackaday.com/2023/04/10/your-multimeter-might-be-lying-to-you/
Tomi Engdahl says:
https://lygte-info.dk/info/DMMReviews.html
Tomi Engdahl says:
How to Turn Off Ghost Voltages with Dual Impedance (LoZ) Meters
https://www.youtube.com/watch?v=JRXTFxsA_lA
Tomi Engdahl says:
In the Know: LoZ and Ghost Voltages
https://www.youtube.com/watch?v=jWc6LfJtbqw
What is Ghost Voltage?
https://www.youtube.com/watch?v=gVi9I7-KJfU
Tomi Engdahl says:
How To Determine If Voltage Is Real Or a Ghost Voltage Using your Fluke Digital Multimeter
https://www.youtube.com/watch?v=mRwsxmn2P-s
In this video, you’ll learn how to determine if voltage is real or a ghost voltage.
Ghost voltages are caused when energized circuits and nonenergized wiring are located in close proximity to each other, such as in the same conduit or raceway. This condition forms a capacitor and allows capacitive coupling between the energized wiring and the adjacent unused wiring.
When you place your multimeter leads between the open circuit and the neutral conductor, you effectively complete the circuit through the input of the multimeter. The capacitance between the connected, hot conductor and the floating conductor forms a voltage divider in conjunction with the multimeter input impedance. The multimeter then measures and displays the resulting voltage value.
Most digital multimeters today have an input impedance that’s high enough to show this ghost voltage, giving a false impression of a live conductor. The meter is actually measuring voltage coupled into the disconnected conductor. But at times, these voltages can be 80-85 % of what the “hard” voltage should be. If not recognized as a ghost voltage, additional time, effort and money will be lost troubleshooting circuit problems.
Tomi Engdahl says:
How to Calibrate Inexpensive Multimeters
https://www.youtube.com/watch?v=-izNaaLWG1k
Here is how to calibrate low-cost multimeters. This is very simple and only takes about 10 minutes with the right equipment.
Tomi Engdahl says:
HOW TO FIX A MULTIMETER THAT DOES NOT WORK (MY TOP 3 PROBLEMS & REPAIRS)
https://www.youtube.com/watch?v=zBXfmXwBsww
In this video we look at common issues with multimeters.
Tomi Engdahl says:
https://www.eevblog.com/forum/testgear/are-uni-t-multimeters-any-good/
Uni-T is one of the two principal multimeter makers in China, the other one being Mastech.
The company is privately owned and based in Hong Kong, with manufacturing done in mainland China.
Since their main market is China itself and emerging economies, their equipment is built to a price, with varying levels of quality.
In general, the quality is acceptable, considering the low price.
Be aware that input protection on most of their devices has been minimal, without much respect for updated international norms.
I have tested my UNI-T multimeters on mains (240VAC), on all possible selections. UT71B/D and UT61E survived without a whimper of protest, even the pocket-size UT120. No life changing experience yet.
Having said that, input protection is minimal and staying away from the mains is a good idea.
There are no fuses in the 120C. Just a self recovery 250V 400mA overcurrent protector (WH250 400) (Polyswitch).
It is rated for 250V, so should be able to handle the mains on it, but I don’t want to damage the meter, in case it doesn’t.
I don’t expect anything drastic to happen though.
No, to all meters, of course, but the Uni-Ts are not build that well regarding safety.
Fluke has a nice document called “ABCs of multimeter safety” which explains this stuff quite well.
It is better to assume that any multimeter that is not a Fluke, Agilent, and possibly Brymen, is not safe until shown otherwise. I have not see one, not one Uni-T that actually has proper input protection. I will believe this meter owned by the OP is not safe for mains until I see the insides. This will be a belief based on the track record of the manufacturer.
Tomi Engdahl says:
The history of the multimeter
https://www.fluke.com/en-us/learn/blog/digital-multimeters/multimeter-history
When was the multimeter invented?
The first device that could be considered a predecessor to the multimeter showed up in 1820 It was a moving-pointer current-detecting device, called a galvanometer. Designed only to detect electrical current and could make a compass needle move, the galvanometer was useful in the lab, but very bulky and delicate, so impractical for fieldwork.
Who invented the first multimeter?
In 1920, a British Post Office engineer, Donald Macadie, is credited with inventing the very first multimeter. The story goes that he was frustrated that he needed to carry a bunch of different tools when working on telecom lines, so he created one tool that could measure amperes, volts, and ohms. Leading to the product being named the AVOmeter.
The first AVOmeter itself was quite clunky compared to the digital multimeters we are used to today. But over the first decade of the multimeter’s life, it shrunk considerably, creating a portable version with additional range and features by the 1930s.
The history of the voltmeter really picks up when Westinghouse introduced the first Universal meter. The original AVOmeters only measured direct current (DC), resistance, and voltage in 13 different ranges. When the “copper oxide instrument rectifier” was made, the meter featured the ability to measure alternating current (AC) and upped the ranges from 13 to 20.
The Fluke 8020A digital multimeter
The world’s first successful handheld digital multimeter, or a voltmeter with multimeter features — gave field technicians the troubleshooting capabilities once reserved for lab specialists. The Fluke 8020A digital multimeter made big news in 1977.
It changed Fluke’s focus from a maker of bench test instruments into the world leader in handheld electrical test tools.
Tomi Engdahl says:
#7 Best Cheap Multimeters (For Electronics & Cars, 2023)
https://www.yamanelectronics.com/best-cheap-multimeters-cars/
Tomi Engdahl says:
7 Best Multimeters in 2023
https://www.gadgetreview.com/best-multimeter
The best multimeter we tried was easily the Fluke 115 Compact True-RMS Digital Multimeter. This multimeter accurately measures true root mean square (RMS) voltage, resistance, continuity, frequency and capacitance, with a CAT III 600 V safety rating and a bright LED backlight for working in dimly lit areas. A multimeter is a top-rated tool that all electricians or DIY enthusiasts should have in their tool box.
Tomi Engdahl says:
5 Best Multimeters (2023 Guide)
https://www.thisoldhouse.com/tools/23276192/best-multimeter
Tomi Engdahl says:
Review of UNI-T UT61E digital multimeter
https://lygte-info.dk/review/Review%20UNI-T%20UT61E%20UK.html
The UT61E is a 4½ digit meter and can show reading up to 22000, in this article I will check it out. The meter is one of the meters in the UT61 series, that at the current time has 5 models with slightly different functions.
The meter is a true rms meter, this means that it can measure correctly on most AC voltages/currents, not only clean sinus waveforms.
The meter is rated as CATIII/CATIV, this makes it safe for use just about everywhere (If the ratings are correct).
The meter has four input terminals. The COM terminal that is used for all measurements and 3 terminals that is selected, depending on what has to be measured. There is one terminal for 10A current range, one for all the other current ranges and one for everything else. This is a good design for input terminals.
In the specifications it says that the V input terminal has overload protection to 750VAC/1000VDC, but the explanation of each range (Except volt) recommends to stay below 30VAC/60VDC for safety.
UNI-T UT161/UT61+ Series True RMS Digital Multimeters Overview
https://www.youtube.com/watch?v=Fqc5c-_x8LA
Tomi Engdahl says:
Analogue Multimeters
and the dB Scale
http://www.marcspages.co.uk/tech/5101.htm
Tomi Engdahl says:
What are the hazards of multimeter?
Momentary high-voltage transients or spikes can travel through a multimeter at any time and without warning. Motors, capacitors, lightning, and power conversion equipment, such as variable speed drives, are all possible sources of spikes.
https://www.ihsa.ca/pdfs/safety_bulletins/safety_bulletin_multimeters.pdf
Tomi Engdahl says:
What are multimeter safety precautions? Before you take a measurement with your multimeter, you should visually inspect it first. Check the meter, test probes and accessories over for signs of physical damage. Make sure all plugs fit securely and keep an eye out for exposed metal or any cracks in the casing.
https://www.fluke.com/en-us/learn/blog/safety/multimeter-guide
Tomi Engdahl says:
How to use digital multimeters (DMMs) properly and how to choose a safe multimeter
https://www.hioki.com/us-en/learning/usage/testers_1.html
Tomi Engdahl says:
Fluke 83, 85, 87 service manual
https://assets.fluke.com/manuals/83_85_87smeng0500.pdf
Tomi Engdahl says:
Glass vs Ceramic Fuses, What’s the Difference?
https://forum.digikey.com/t/glass-vs-ceramic-fuses-whats-the-difference/8475
Note the breaking capacity at rated voltage. The ceramic fuse is much higher at 100 amps compared to 35 amps for the glass fuse with the same AC voltage rating. The breaking capacity is the maximum current that can safely be interrupted by the fuse. A ceramic fuse offers better thermal and arc protection during a high current episode compared to a glass fuse with the same specifications.
Important note: The fuses mentioned here are your standard glass and ceramic cylindrical fuses used in hundreds of household goods and electronic devices, these are not HRC (High Rupture Capacity) fuses used in high power equipment and multimeters even though some may look similar. Never replace an HRC fuse with one of these common glass or ceramic fuses.
Tomi Engdahl says:
https://elektroniikka.narkive.fi/6w9ALyBS/mitka-ovat-yleismittarin-diy-sulakkeen-vaarat
Tomi Engdahl says:
Multimeter explosion
https://youtu.be/i9jpwGTy66g
Tomi Engdahl says:
https://www.digikey.fi/en/blog/what-are-multimeter-cat-safety-ratings
Tomi Engdahl says:
https://www.skillcatapp.com/post/safety
Tomi Engdahl says:
https://www.cem-instruments.com/en/goods-id-826
Tomi Engdahl says:
SIBA Fuse 70 180 40 500mA 660V FF500mA FF Fuse DMI Fuse 5x20mm x2/5/10 JPSF467
https://www.ebay.com/itm/273926177072?hash=item3fc745c130:g:GdwAAOSwb2xdKG-J&amdata=enc%3AAQAIAAAA8HAjz%2FGSNKEwDfYnaLmXHthfbKBr5liWWXU4RPrNTveCFzmc9XFKckql%2FMnehUrdv2scZh53VDR5eyLguiW1FYsVx99O4X9XWSIVdFxahscoqH4h0tBTcC7DHjoIeu6a4MSxTTTpUHydxHuKAGBBamL%2Bu8qwK0c%2BrfO0Pfo8yUiWr4ELNQ%2F10SilDM3t16GFkooqmyDrcSRdDJoaV8lXg2TPHsLL%2FdC0fsTjgQ5U7AzZxJ%2BQPA2cJdt%2Bk1wEWC0aXIzv3wLMHHZiNcRT6uNDJpfxuqTPCWfeywlaOxLngHHCY3eeCsHO5KKowScOmMd76A%3D%3D%7Ctkp%3ABk9SR4yLzLiOYg
Genuine SIBA 70 180 40 500mA 660V DMI-Fuse Fast Acting
DMI Fuse, Ultra Rapid , FF500mA
Construction : Ceramic Tube
Dimensions 5 x 20mm
Rated Breaking Capacity 100 kA @ AC/DC 660V
Available in quantities of 2 5 or 10 fuses
Tomi Engdahl says:
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313&_nkw=ceramic+fuse+500+ma+660+v&_sacat=0&LH_TitleDesc=0&loc=1005576&mktype=&sitelnk=&poi=&cmpgn=18791967021&rlsatarget=dsa-1680301660446&geo_id=&network=g&mkscid=102&gclid=EAIaIQobChMIkrKHwrOg_wIVQuKyCh1LGA8sEAMYASAAEgJxpvD_BwE&mkcid=2&_odkw=ceramic+fuse+500+ma+600+v&norover=1&MT_ID=&adpos=&adgroupid=142641908346&matchtype=&abcId=&keyword=&mkrid=711-153677-346401-4&crlp=651204051578_&device=c
Tomi Engdahl says:
https://www.cem-instruments.com/en/product-id-996
Tomi Engdahl says:
http://www03.edu.fi/oppimateriaalit/kunnossapito/mekaniikka_y1_yleismittarit_ja_niiden_kaytto.html
Tomi Engdahl says:
In general, when evaluating a multimeter, consider the following aspects:
Accuracy and Precision: A good multimeter should provide accurate and precise measurements across various ranges.
Functionality: Check the range of measurement capabilities it offers, such as voltage, current, resistance, capacitance, frequency, temperature, etc. Ensure it meets your specific needs.
Build Quality and Durability: The quality of the materials used and the overall build of the multimeter can affect its longevity and resistance to wear and tear.
Safety Features: Look for features like overload protection, fused inputs, and proper category ratings to ensure safe usage in different environments.
Display and User Interface: A clear and easy-to-read display, along with an intuitive user interface, can enhance usability and convenience.
Price and Value for Money: Consider the price of the multimeter in relation to its features and overall quality. It’s important to find a balance between affordability and performance.
Tomi Engdahl says:
How to make your own Leads, Probes, Lights, Attachments for an Oscilloscope or Multimeter (DIY)
https://www.youtube.com/watch?v=M2VRWNY_nfQ
Tomi Engdahl says:
“Range Confusion”? Which DMMs Have This Problem?
https://www.youtube.com/watch?v=x7rcUYT6h2k
Some multimeters give erroneous readings when the selected current range does not match the designated jacks the leads should be in. I went through some of the DMMs I have and let’s find out which ones have this problem.
00:00 Problem demonstration with Zotek ZT-702S
02:40 Kaiweets ST600Y and ANENG AN009
04:03 HoldPeak HP-770D, BK 2709B
05:59 HT118E, HT118A
07:40 ANENG AN870, UNI-T UT61E
08:40 ET829, Hantek 2D72
09:58 OWON HD200 series, conclusions
Tomi Engdahl says:
Multimeter measurements on adjustable speed drives utilizing the new Fluke 87V DMM
https://www.fluke.com/en/learn/blog/motors-drives-pumps-compressors/multimeter-measurements-on-adjustable-speed-drives-utilizing-the-new-fluke-87v-dmm
Tomi Engdahl says:
Measuring a 4-20mA analog signal with a basic $10 multimeter.
https://www.youtube.com/watch?v=S4-HB7knpLE
Measuring a 4-20mA signal can be one of the more difficult task. Many people think you need a Fluke 771 or 773 to read an analog signal but you can do it with your basic $10 meter. The trick is you must make your meter part of the 4 to 20 mA current loop. We are also going to show you some easy ways you can blow the fuse in your meter when troubleshooting a 4-20mA circuit and how to tell if the fuse is blown in your meter without opening it up.
Measuring a 4-20mA signal without blowing the fuse in your meter
https://www.youtube.com/watch?v=pDSUfqso_eA
A 4 to 20 mA loop will have a output device that produces or regulates a milliamp loop and an input that will read the value. When using a 4-20mA source the positive terminal of the output will go to the positive terminal of the input and the negative terminal of the input will go back to the negative terminal of the analog output.
Examples of outputs could be the position of a valve, a flow meter, temperature, pH, or ORP. Pretty much anything where you need to make a measurement that isn’t simply on/off or good/not good. Examples of inputs could be a PLC, display meter, data logger, or a speed control on a drive.
Where a 4-20 mA loop gets tricky is that you can have multiple input devices connected to an output as long as they are all in the loop. So say the input on the right is a PLC and someone wanted a local display. They would cut this wire then connect the plus of the milliamp output to the plus of the local display then connect the minus of the local display to the plus of the next input device.
When troubleshooting a milliamp circuit your first inclination will be to grab your amp meter. It makes sense but this is made to measure big amps, in this ones case, big amps. We need to measure milliamps which is a much smaller meter. If you google “4-20mA meter” then you are going to come up with some expensive solutions such as this Fluke 772. But don’t fret. You typical affordable meter such as this one https://amzn.to/3v4WCaI can measure a 4-20mA signal.
One thing you must pay close attention to when testing a mA signal is down near the terminal post where it says fused. Nearly all volt meters are fused and the post common way to blow a fuse in a volt meter is when checking milliamps.
I’ve heard of instructors that would give students a lower grade if they blew the fuse in their meters. Students, if this happened to you then sorry about your luck but trust me, you just got a valuable lesson that will help you in the real world. Instructors, if you are doing this will you please stop. If your budget doesn’t allow for you have replacement fuses then call us and we will donate some to you.
Now before we can understand how to prevent blowing fuses in our volt meter we need to understand how they get blown. So we take our positive terminal of our volt meter and connect it to the positive terminal of our mA output just like we typically would when checking voltage. Then we take the minus of our voltmeter and connect it to the minus terminal of our volt meter. When reading mA on our voltmeter there is a small fuse in the circuit and for our purposes there is no other resistance in the circuit so we are dealing with a short circuit. So the moment touch these two leads to the circuit we blow the fuse in the meter.
In order to properly test a 4 to 20 mA loop you must be part of the loop. So instead of connecting it across the circuit you must remove one of the wires. It could the positive or the negative wire. Then connect your meter through the loop. Then your meter will only see between 4 and 20 milliamps preventing the fuse from blowing.
Tomi Engdahl says:
https://www.fluke.com/en/learn/blog/electrical/how-to-measure-a-4-20ma-loop-signal
Tomi Engdahl says:
https://www.fluke.com/en/learn/blog/digital-multimeters/multimeter-dial-button-jacks-display
Tomi Engdahl says:
https://kaiweets.com/blogs/news/how-to-test-audio-signal-with-multimeter
Tomi Engdahl says:
https://toolsweek.com/how-to-test-audio-signal-with-multimeter/
Tomi Engdahl says:
https://www.familyhandyman.com/article/multimeter-symbol-guide/
Tomi Engdahl says:
https://www.eevblog.com/forum/beginners/measuring-audio-interface-outputs-with-multimeter-need-some-guidance/
Tomi Engdahl says:
Topic: Uni-T UT20B multimeter square wave output test — what is this ? (Read 11527 times)
https://www.eevblog.com/forum/testgear/uni-t-ut20b-multimeter-square-wave-output-test-what-is-this/
As I recall, that particular meter can output a square wave that you can use to fault find the stages of a circuit (usually audio amplifier stages).
My guess is that it is outputting a square wave and the amplitude is what shows on the display and is variable depending on the load. Seems a dangerous test since the amplitude cannot be controlled. Even the instructions say do not let it get over 10 volts with a 12 v battery?
Try ‘measuring’ across some resistors with your meter set to square wave mode, see what you get. If you measure across a 1M resistor does it read 3 Vp-p?
BTW the manual does give further info on the square wave source: “Output approx. at 50Hz square wave. As a simple signal source with 47k? resistance output.”
Tomi Engdahl says:
Topic: Uses for the Square wave fixed frequency output on DMMs? (Read 3424 times)
https://www.eevblog.com/forum/testgear/uses-for-the-square-wave-fixed-frequency-output-on-dmms/
This time, I would like to ask about the fixed frequency output “square wave” function of multimeters. Usually it’s a fixed 50 Hz with 0.5 duty cycle. At least a few meters offer it, starting from the famous DT series.
What could this function be used for? In case it’s only available on cheap multimeters, I would assume it’s not designed especially as a kind of test signal for a scope, plus it likely wouldn’t make a good/accurate one anyway.
I’m not sure if there’s enough power to test with any LEDs or beepers. Maybe for testing simple transistor amplification circuits? If you only have a transistor, an LED and no other source for the gate signal, perhaps it makes sense. Maybe there’s no specific intention, but I imagine this could have more uses than the manual hold button.
Given that it is only found on cheap meters, unlike the hold button, I am not so sure about the more useful part
I heard once that it function being used for checking the segments on the liquid crystal displays or something.
Maybe it is for testing some kind of audio device. :-// I tried using it to test some audio amp and it outputs something like the 50Hz mains hum (like when you plug in a guitar cable for example.)
Whatever priced meter it’s on, it would be handy as a go / no-go speaker tester, or certain mf types of capacitors ?
Keysight U1252B User’s and Service Guide: Square Wave Output
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The square wave output function can be used to generate a PWM (pulse width modulation) output or provide a synchronous clock source (baud rate generator). You can also use this function to check and calibrate flow-meter displays, counters, tachometers, oscilloscopes, frequency converters, frequency transmitters, and other frequency input devices.
On this specific meter you can adjust the frequency, duty cycle and pulse width.