In Praise Of The DT830, The Phenomenal Instrument You Probably Don’t Recognise For What It Is

If we had to make a guess at the single piece of electronic bench equipment owned by the highest proportion of Hackaday readers, it would not be a budget oscilloscope from Rigol, nor would it be a popular portable soldering iron like the TS100. Instead we’re guessing that it’s a multimeter, and not even the most accomplished one.

The DT830 is a genericised Chinese-manufactured 3.5 digit digital multimeter that can be had for an astonishingly low price. Less than a decent hamburger gets you an instantly recognisable plastic case with a chunky rotary range selector switch, and maybe a socket for some kind of transistor or component tester. Make sure that there is a 9 volt battery installed, plug in the pair of test leads, and you’re in business for almost any day-to-day electrical or electronic measurement. They’ve been available in one form or another for decades and have been the subject of innumerable give-aways and loss-leader offers, so it’s a reasonsble guess that you’ll have one somewhere. I have three as far as I know, they make great on-the-go instruments and have proved themselves surprisingly reliable for what they are.

Persuading You Is Going To Be A Tough Sell

An undervalued instrument, by my estimation.
An undervalued instrument, by my estimation.

If you talk about the DT830 in polite company, you might be greeted with snorts of derision. It’s not difficult to find reviews that tear one down and compare it to a more expensive meter, and not surprisingly find the pricey meter to be of higher quality.

And it’s certainly true that for a couple of dollars, you get a switch that won’t last forever and high voltage isolation that maybe isn’t quite up to spec. But I’m going to advance a different take on the DT830 that may surprise some of you: to me it’s a modern classic, an instrument that provides performance for its price that is nothing short of phenomenal. Because that pocket-money meter not only measures voltage, current, and resistance, it does so accurately and repeatably, and to compare that with what might have gone before is to show just much better a device it is.

Thirty years ago, a digital multimeter was an expensive item, and most multimeters were still analogue. A cheap multimeter was therefore invariably a small pocket analogue device, and the very cheap ones could be astoundingly awful. Accuracy and repeatability in reading wasn’t their strong point, and while I am a great fan of analogue multimeters when it comes to spotting dips and trends in tweaking analogue circuitry, even I can’t find reason to praise the inexpensive ones. By comparison the DT830 delivers reliable and accurate readings with a high-impedance input, something I would have given a lot for in 1985.

That Performance Is No Fluke

An ICM7106 epoxy blob on a 40-pin DIP-shaped PCB
An ICM7106 epoxy blob on a 40-pin DIP-shaped PCB in this roughly 18-year-old DT830

So given that it costs considerably less than a pint of beer in a British pub, how does such a cheap instrument do it? The answer is, by standing on the shoulders of giants. My colleague Anool Mahidharia supplied the answer here back in 2017 when he took a look at the Intersil 71XX series of integrated circuits; the archetypal DT830 contains an ICM 7106 3.5 digit digital panel meter chip, whose roots lie in a much more exclusive stratum of the industry.

(Despite there being a load of newer and more accomplished multimeter chips on the market I was surprised to find that none of them had found their way into the meters I’d opened.)

The ICM 7106 was based on work Intersil did in 1977 to produce the part in Fluke’s first portable DMM, the model 8020A.

Google hasn't found any ICM7106 conterfeiters!
Google hasn’t found any ICM7106 conterfeiters!

So you’re not getting anywhere near the physical design or component quality of that expensive meter, but you are benefiting from the tech that made its ancestor a very good instrument for the 1970s. The dual-slope integrating ADC and precision reference are the same as the ones in many far more expensive meters, which is what makes the reading from your few-dollar DT830 one you can trust. Not bad for something you might dismiss as a piece of junk!

If there is something to be gleaned from this story, it is a very real demonstration of the power of semiconductor manufacturing. Assuming it has passed acceptable factory QA, every 7106 is as good as any other 7016, from the first one made by Intersil in the 1970s through to the unknown-origin chip hiding under an epoxy blob in my cheap meter. The manufacturer can skimp on every other component in the meter, but assuming that there’s no money in counterfeiting a 43-year-old chip that long ago left its premium product phase behind and has been manufactured by many sources over the years, they can’t skimp on the chip that powers it. To be an ICM7106, it must have the same features as the original from the 1970s, thus my bargain-basement meter still shares something that matters with one of far higher quality.

The DT830 multimeter, then. It may be a heap of junk, but it’s an astonishingly good heap of junk. I for one, salute it.

130 thoughts on “In Praise Of The DT830, The Phenomenal Instrument You Probably Don’t Recognise For What It Is

  1. I am a proud owner of one. It’s an Elro M630. But inside, the PCB is marked M830B-16B. Mine is stamped 2398, so I presume it’s week 23 of 1998, which should make it 22 years old. :)

    And yes, it still works great. It has never let me down.

    I feel so proud now!

    ;)

  2. I’ve compared some against voltage standards and they’re all right on. Only had one die on me, probably the epoxy blob passivation over the chip.

    The only complaint I have is that the leads are crappy. I sure wouldn’t trust them with higher voltages, and they frequently break.

    The most useful meters are the ones with a continuity buzzer. I’ve only used the transistor beta function a few times, and the temperature function (which requires a thermistor probe) never.

    1. The leads are actually a safety part – they saved my friend’s DT830 by fusing faster than anything else inside the DMM when he tried to measure mains voltage while forgetting the leads in the current measurement position :D :D :D
      There were no visible external signs of the leads being bad, it did took me sometime to find out what was wrong with the DMM (my friend only told me “it’s now only giving me random readings…”).

    2. I’ve got some older and newer ones and the old ones have pretty decent leads (I broke one sadly). The new ones are nearly devoid of copper :P I’m not sure how the “10A” mode is supposed to work like that. “Unfused” it says, well in this case the lead is the fuse and it will blow at much less than 10A I’m sure.

      But the old ones are actually quite decent so if you have one of those with a leaky battery, don’t throw out the leads!

  3. Oh boy. I wonder how many comments this article is going to get.

    The ICM7106 IC may be perfectly good and destined for the hall of fame, but what about the rest of those cheap multimeters? Inexpensive leads, inexpensive jacks, and inexpensive safety measures (if any) means at best an annoyance to use after a while when they start deteriorating and at worst an electrical (or even blow-up-in-your-hand) hazard when used for anything more than 5V electronics (OK, maybe 12V.) Just don’t use a $10 multimeter. A few dollars more will get you something much more reliable and safe.

    1. Use something better for the bench. But if you frequent ham radio and electronics flea markets, or if you do field radio operations, a cheap multimeter is an essential tool. You don’t want to risk your more costly instrument there; it’s the perfect place to take your freebie from Harbor Freight or something you bought for $5 from wherever. In those settings you’ll either be using measuring resistance or DC voltages that top out at 12V or so (AC power isn’t available) so safety of the instrument is not an issue.

      1. I agree but Not one of those.
        Spend a bit of money and buy something in the $50 or $75 range that you can depend on.
        I’ve seen a friend come up short at Field Day when one of those didn’t work.
        Thankfully I had my 1990 Becaman RMS225 that had been my workhorse at my full time job as a two way radio tech.

      2. I couldn’t agree more. My M830 was my first digital meter. Before that, I was using an analog Philips bench multimeter. And after my M830, I bought a Fluke. I’m not sure if anything beats a Fluke, but I was building a Geiger Counter, and even IF the input impedance of the M830 is high, it’s not high enough to measure the voltage of the cascade (because it has such weak amperage). When I measured it with my Fluke (I tried with my M830 first, in case I would destroy anything ;)), the voltage measured was within 1% or 2% of what I had calculated it to be.

        The main reason I have the M830 is it’s size. Flukes are giant, don’t fit in my pocket.

    2. Horses for courses, right? I have four meters in active use, two Flukes and two generics.

      Fluke 20 (discontinued) I’ve had since the mid-90s, and it’s never let me down, but it doesn’t do current. Fluke 116C has a good microamp meter, calibrated temperature, and a LoZ function which is good for diagnosing voltage sag. (Batteries that say 1.5 until you pull more than a few mA…) I would trust either of these up to their rated voltages.

      Two cheapies: both have ammeters, and both measure reasonably well. They’re the type of meter that Jenny’s writing about, although different models. Don’t plug them into the mains.

      So you need to simultaneously measure current and voltage: you’re happy to have two meters. You need some specialty function like temperature or microamps, or glitch logging, or… That extra cheapo meter frees up your specialists to do their job.

      Toss in an oscilloscope, and you’ve got something!

    3. If you’re paying $10 for one of these, you’ve got yourself to blame.

      I use these multimeters because they cost $1, and every few months I get a coupon for a free meter with a $5 purchase.

      Is it a lousy meter? Yes. My Fluke is a whole lot better. Is it good enough for basic troubleshooting and testing batteries? Also yes. Is it worth $1? Definitely.

      1. Yup, it’s so cheap you can hardly buy the battery for that price! I keep them in places like vehicle trunks, my battery shed (I’m off the grid) and just around the place so I’ve always got a meter at hand. Sure, I have a few “really good” other ones at my main tinker benches, you bet. Not the point.

        This is more like – as a guitarist and studio owner, there always seemed to be shortage of picks (excuse? probably). So one day we went to the store, and for a pretty low amount of money, bought a lunch bag full of various picks, tossed them at the walls of the studio at random, and never had to hear that baloney again.

        These meters are like that. You want something better – that’s on you, go get up and get it from the real bench.

      2. Timex’s ads used to show two watches run over by a vehicle, with the tagline “To replace the watch on the right costs less than to replace the glass in the watch on the right” Where left was the timex and right was a rolex or longines or something.

        This is what we’ve got with the super cheapy meters, to replace the meter costs less than to replace the fuse in a Fluke (With one of sufficient quality that you have no worries about it protecting the meter)

        1. Finally stopped with “where the hell did it leave it this time?” because I probably have 10+ of these around the house now and my chances of finding at least one of them are pretty good (perfect for 220V, battery & continuity tests), even ordered a few buzzerless models by mistake and gave them away to my ‘friends’. 2.80€ and a good month for the slow train from China to Europe.

          https://www.aliexpress.com/item/4000492574811.html

          1. I heard of a rancher who’s hired hands kept losing slip joint pliers.
            Finally, he made a trip to town, and came back with a big box of pliers.
            He set them down in front of the hired hands and said, “Here! Now come Spring, if I can’t find ONE pliers, you’re all fired!”

            B^)

    4. In 1978, maybe ’77, I bought the DVM kit from intersil. It was the LED version, they had one with an LCD display, but I think that was more expensive. I paid at least fifty dollars. An “evaluation kit” for the 7106/7107, I’m sure I wasn’t the only one to buy the bosrd becsuse it was a cheap way to get a DVM.

      So why not treat these cheap DMMs as evaluation boards.? Extract the board, and use it as a 0-200mV meter, adding your own switch and divider chain, and whatever jacks and leads you need. At least if the needed points sre accessible.

      Cheap means never having to say sorry, just buy another

    5. There’s a saying in photography: “The best camera is the one you’ve got with you”. These are so cheap you can have many lying about the place. You’re not going to have a Fluke lying in your car as well as your bench lab, in your hackerspace locker etc all at the same time.

      And really they perform well. Except for the safety thing I wholeheartedly agree (and combining mA and high voltage settings on the same jack promotes stupid mistakes turning the knob). But really, if you keep your wits about you it’ll be OK.

  4. About a year ago the Aneng 800x series was the cheapest and greatest.
    I bought 2 AN8009, cause the lack in current shunt is made good with the 1uV voltage resolution, and I prefer external shunts anyway.
    (With an external shunt, you can leave it on your breadboard (or whatever) and use the DMM for something else, without opening the circuit)

    I don’t use those meters much because I abhor the way it beeps at me and goes turns itself off all the time. And then, after about a year and 5x use or so, the resistance measurements is not stable anymore. Sometimes it settles 10% off the actual value. Yuch!

    1. I once had a similar cheap meter in my car which needed a small 12V battery, which normally is extremely expensive (one for 5€), if you can’t wait for China delivery (5 for one €). As it does not turn itself off after some time, one time the battery was empty when I needed it. When I tried to find a replacement battery in a big store like TESCO, I instead found a meter which looked much like this DT830 for just 4€ – battery included. Yes the leads were crappy and I replaced them in the meantime. But the meter is still in my car and often very useful. Last time on a camp site when we had numerous extension cords cascaded over 50 to 70m and I had to find the fault.

  5. I have been a fan of these inexpensive meters for decades now. I must have 6 of them still in their HF blister packs from when they used to be freebies. I mist have twice that many in my various cars, trucks, sheds and shops. On the really old ones the single biggest point of failure was the zebra strip to the display. They got rid of that perhaps 10 years ago and now they are tough little buggers. I have much nicer meters but I tend to keep them in more sheltered conditions. They definitely have their place.

    1. That’s one cool professor! Great project. I’m just a little too old to have done those kinds of projects in college. I graduated a few years (maybe more than a few…) before “commodity” maker-grade hardware hit the scene. Now you can get an Arduino, some sensor modules, power supplies, motors, comm modules, jelly bean passives, or whatever for pennies and have them shipped to your door step the next day (for a small price) or in a month (for free).

  6. I agree whole-heartedly with the article. I have one that is the same as the photo in this article, except it says Pro-Tester instead of Sinometer, but in the same font. I apparently got it at Radioshack in 1998, when I was broke, and used it until earlier this year. Before that, I had an analog Archerkit meter my dad got me for christmas and told me, “you’ll burn this out testing voltage on the ohmmeter mode but knock yourself out, kid” (can you believe the warning worked and the meter still works?)

    My only complaint is the same as everyone else, the leads! For years I have been frustrated at the leads. Twice I bought better quality leads only to discover the jacks they go into are subtly mis-sized and can’t accept any others. I’ve repaired them plenty of times, and red doesn’t match black so I must have found a replacement set somewher along the line, but I guess the points themselves are oxidized. Just endless grief from these darn probes!

    I recently got a Fluke 107 to replace it, because I have come to the idea late in life that I have plenty of money and can throw it away for nothing. Obviously, the leads are better. Other than that, the only feature I like is that it turns itself off if I forget to. A heck of a lot of money to spend on those two features. Would have been as happy hacking together better leads for the Pro-Tester!

    1. At the FE college I work at I dug up a box of the pro-tester marked ones as kits, & have been handing them out to students that look like they care. They deffo beat the shit out of not having a meter.

  7. I have 3 of the pinkish ones and two of the yellow ones. Great for messing with a transistor or constant current circuit. One monitors emitter voltage, another emitter current, same for base and collector. Don’t need accuracy just quick check of the info. But they are all pretty close according to my DMM checker. I have a Heathkit dmm I put together 40 years ago if I need more accuracy.

  8. This has been my first multimeter from age 8 to 14, has made multivibrators possible by testing random transistors, blown countless fuses in its bowels… this is a great part of my childhood and I cannot even remove that PCB from my memory, it is written deep!

  9. Ever since my fluke was left on the garage floor and run over by a car, I love these cheap meters, I don’t care much if they get run over, dropped in water or lost somewhere.
    I have one in each car, and a few in the garage.
    The fluke lives indoors now.

  10. As indicated in the article, I too have several of these venerable meters tucked away in various places so one is always handy. One is always on my bench, never far away from my vintage Fluke 79! For most meter applications, they are interchangeable and I always trust the measurements!

  11. Mine (bought about twenty years ago…) says ‘DT-830’ on its front. Does it mean I have the original brand? :)

    I do not own any other – I do not mind that it is low-quality meter, as I am a low-quality hobbyist. The only feature I miss is the sound circuit tester – the display tends to dangle away just when I need it most…

  12. I have more of these than I can count. Some bought and some free. Many given away. They are my “go to” DMM. I’ve got a pair of 34401As, a 3457A and other DMMs, but in practice these are what I use most. In part because I have them everywhere. I’ve got better meters in toolkits and locations that need them. These are my base case.

    Most (I can’t possibly find “all”) have been checked against standards checked to a few ppm and all tested have been in spec. Versions with trimmers can be adjusted to less than 0.1% DC error. IIRC they beat the low end Fluke DMM specs of the late 70’s out of the box.

    They are only 1 Meg Ohm input, so you sometimes need to correct for that. Beats a 50K VOM, but not an 11 Meg VTVM.

    I *think* I have had one fail. Best guesstimate is I have around 30 of various vintages, mine and Dad’s.

    One of these, some basic hand and soldering tools and a bunch of early morning trash route drives will turn up a lot of stuff which can be repaired and resold in sufficient volume to start a business. This is especially true with appliances. I scavenged audio gear from the trash and fixed it in grad school to make money. And I just did the stuff I found going to and from school.

    1. don’t be trusting you life on anything but with a Fluke, or two. Fluke has an awesome customer service, they sent me a free high presions resistor that had opened . An old saying goes “Imitation is the sincerest form of flattery” so they copied the Fluke,

      1. That was my experience as well.

        I took a chance on a broken Fluke 75 for $5 at a flea marker. (Mostly working, but some functions clearly not working.)

        Anyway I called Fluke about two replacement parts (likely someone measured voltage when in current mode.)

        Fluke asked for my name and address and perhaps serial number. A quick check of their database confirmed this was my first request for parts.

        The parts arrived a week later. For FREE. Thanks Fluke!

  13. You can sure as heck skimp on the stuff that makes a meter safe to hook up to 1000 volts or reasonable to run 10 amps through. Basically all of them are labelled 1000V and 10A, and a lot of them are labelled as Cat II, which most of them probably are not. It can be as accurate as it wants and it’s still not a great deal if it kills you.

    This stuff is likely to be bought by kids and beginners, who are less likely to understand that the markings are suspect.

    If you’re going to buy a meter marked like that, you should only do it if you’re sure the people you’re buying it from are actually delivering it. Otherwise, even if *you* know not to trust it, you’re supporting people who knowingly put others at risk.

    1. “This stuff is likely to be bought by kids and beginners, who are less likely to understand that the markings are suspect.”

      The silver lining here — which I can attest to as a life-long beginner, myself — is that we don’t need to understand much about meters to be afraid of high voltage or high current. Man, I’m afraid of anything over about 15V. I occasionally poke around at a 120V circuit but I avoid it for anything. You won’t catch me working with 480V 3-phase or high-voltage coils for anything. And the 10A mode isn’t there to measure 10A, it’s there so that you can measure 200mA +/- 100mA without bumping into the limit, it’s not actually for measuring like current flow into an R/C airplane motor, or current flow at 120V, jeesh!

      In short, if you’re actually doing something dangerous, you’re either not a beginner or you’re so reckless that your crappy meter is the least of your concerns.

    2. I have to agree. These are marked for voltages I would never trust them to be safely used on. I regularly work on 600 volt systems and I trust my Fluke and Hioki meters to give me accurate readings as well as have leads that will definitely withstand that voltage. I worry about people trying to use these on anything other than extra low voltage systems.

        1. The IEC defines extra low voltage as less than 50 volts AC or less than 120 volts DC. The low voltage range is 50-1000 AC and 120-1500 DC. I would agree that any meter should be fine at the extra low voltage range. What concerns me is that one of the reasons we test voltage is to ensure the voltage is the correct one. I have personally encountered 347 volts where I was expecting 120 where someone had used the wrong taps on a transformer. Wiring mistakes happen and counting on a cheap meter can be dangerous in that case.

  14. I like this article. My take on these is that they have their place and I should get one or two.

    The look great for the usual digital stuff I do, the only drawback would be the bad leads. I am seeing complaints, but no recommendations on where to get a better set of leads. I would just avoid using this on mains voltages — I have a fluke for that.

    1. Of my two meters, the cheaper had leads that went bad quickly, but the slightly better built one has great leads that have lasted 10 years at least. The leads that went bad just had the wires break inside the insulation, probably a weak solder joint or an overstripped wire. The problem with trying to repair it is that it’s all potted into the insulation of the connector. I bought a new pair of leads for the cost of the meter at my local home center. Since the meter is still pretty good, I figured new quality leads would probably be a better investment than yet another meter with leads of uncertain quality.

  15. Since ‘Horror Freight’ used to give their little red ones away for free with any purchase, I would grab once in a while and throw it in a lab. They were great for DC voltage stuff and good enough. I had several labs to manage, so I would make it a point to keep one in most of them.

  16. I won’t say what I paid for a Fluke 8000A new back in the day (rather, my employer paid). These throwaway meters meet or exceed it in all ways, except, likely, longevity.

    I still have that meter (I bought it when my employer sent it, and a pile of other older gear, to the MIT flea back in maybe 1989? 1990? A long time ago. Early swapfest) and it still meets (exceeds, actually) factory spec with basically no maintenance. Still my go-to bench meter, though I have much ‘better’ today. Still have my 8030A, as well (same place, different seller about the same time. Pre-8020A. Fluke numbering makes little sense) and it is due for another set of NiMH. NiCad are so ’70’s. True RMS on that one, and also still better than factory spec.

    Never had a real 8020A of my own. By the time I could afford one, I had better. But I salute the lineage and refer ll to the thread on EEVblog started by DrTaylor, who worked on the 8020 and provided some background, and led the 8060 project.

    Been through a few throwaways, most dead via switch failure or battery leakage. Handy. Like wrenches, motorcycles, calipers, and laptops, gotta have at least one beater on hand

    1. Heh. I have a Fluke 8012A sitting on my bench right now! It spent the last 20 years in the garage. The LCD is still in perfect shape! (though the backlight is too dim for my taste). And it still works great. I got it when a previous employer did a lab cleanout (discarded because the LCDs tend to get black splotches on them).

      I do tend to avoid the Cheap Chinese Cr@p, because you never know whether you can trust the readings. I also have a couple of Fluke 77s and a Simpson 260. I know I can trust them…

  17. I remember my uncle telling me about these things years ago: “at that price, I can keep one in the trunk of every car I own.” Any other collector of vintage Jaguars will understand the importance of having ready access to electrical diagnostic gear.

    1. I find a test light is often the far better tool for troubleshooting 12V electrical systems as the incandescent lamp loads the circuit down a lot more than the 1 meg resistor in the cheap multimeter, or worse yet the 10 meg resistor in the good meters. No battery to go bad either. Only time I really use a multimeter on cars is to check drop on battery cables and when dealing with the computer controlled stuff.

    1. Haha great, a new YouTube channel: how to pimp up your 8020A 😀👍 Diamond encrusted probes? Great article, really about just getting on and getting the job done and most of the time, the highest quality is not essential, but simple functionality is really valuable.

  18. Price:
    £3.39 Shipped from China to the UK, gets you a device that will happily measure currents in the zero to 200 uA range.
    Yes, I agree, its a POS, but think about that for a moment. For less than the cost of a jar of cheap instant coffee from your local supermarket, someone will ship you a small cheap black hunk of plastic that will measure uA current, voltage, test diodes, and spontaneously combust when you accidentally connect it across your car battery with it on the current range instead of voltage (don’t ask me why I know). What is not to love about that?

    1. No. not spontaneously combust. It is a deliberate action. One of the undocumented features, except in the boy sprout edition.

      When your fuel pump doesn’t fuel like pumping, or your alternator stops altering, or three of your tires get tired, and you are in the rough, this is your emergency fire start kit.

  19. I have two versions of this type of multimeter. The smaller of the two was $5, and the larger was $10. Both have held up very well apart from the test leads on the smaller of the two. The bigger feels more robust, and it also operates more quickly. Continuity testing immediately beeps on a short. The smaller one has about a 1 second delay on continuity testing.

    I have one other more expensive multimeter, and it has never been as good as either of the cheaper ones.

    I’m very happy with them and based on how often I use them and how I use them, I doubt I’ll ever buy a more expensive one. I’ve got other more pressing tools that are conspicuously absent and need buying.

    Maybe I should open them up and see what’s the difference.

  20. I have several, all pimped up.with a poly fuse, and powered using a usb rechargeable lithium poly phone battery and step up 9v reg.
    The newer mini 830B/L/N are nice and compact. glad you gave them credit. yes the leads are crap, but these ubiquitous meters deserve recognition.

    1. Now that sounds like a nice hack! The basic idea of replacing 9 volt batteries with a lithium ion cell of some kind along with an up voltage converter is a great one. That deserves a Hackaday article of its own.

        1. I’ll watch for your article. I see all kinds of up converters on AliExpress for pennies, so all I need is a small lipo that I can tuck inside the case. I just bought one of these gems at HF. And the one I just bought now has a separate on/off power switch.

  21. I got several of them for my kids, they work great and being able to set up a demo so that they can watch volts and amps at multiple points as they would in a circuit sim is very useful. I looked into the details of that chip in the hope that there was a easy way to interface it to an ESP32 but nothing particularly easy and useful seemed obvious to me at the time.

  22. There have been a lot of complaints about the test leads on an otherwise–in most cases**–very good DMM (some, you have to be on your guard about**).
    Personally, I have never had problems with the test leads, and I carry one of these devices in each of three separate tool bags, and a tool box (that’s why I like the yellow ones–easy to find in a tool bag). On those extremely rare occasions when I have absolutely had to measure any high(er) currents, I strictly adhere to the “ten seconds on, one minute off” rule. Never had any test leads burn up yet.

    I’m baffled: so what’s the problem (assuming you have one of the good versions**) with simply buying a better set of test leads for your low-cost multimeter? I don’t understand…then again, perhaps I do: it’s a psychological problem. You have a $5 DMM, which would have cost you $50 twenty years ago, and you can’t see spending another $5 on a set of really good test leads.

    You’re absolutely correct about one thing: you have a problem.

    *****************************

    **Example (from tear-down experience) of a good- vs. poor-version of (one version of) the DMM being discussed here: Harbor Freight’s old version, labelled “CEN-TECH” (very good; the yellow ones even carried a part number right on the front: P30756), as opposed to what they sell now with no brand name (very poor). And, by the way, H-F has stopped their Free-Coupon promos, at least in my part of the world. That’s a good thing, because even if it were free, their ‘no-name’ DMM would be tremendously over-priced.

    1. That’s a good idea. I installed one on my cheapo digital calipers and the battery life went from 1 month to I haven’t changed it since I installed the switch 5 years ago. The only difference in operation is having to press the zero button after switching it on. Totally worth it.

  23. I will start “Intro to engineering” at ASU in Oct. Under the required materials it listed “digital multimeter”. I thought it was a book on multimeters and I happily added it to my cart in the bookstore. It was only around $12. When it arrived in the mail I was horrified to find out it was just one of these cheap meters. It wasn’t worth my time to send it back for a few bucks so, I threw it on the pile of the exact same meters that i already have.

    My first cheap yellow meter has been good to me since I was probably around 10. The two issues I had were obviously the leads and the zebra strip. The zebra strip didn’t even completely fail, only the decimal stopped showing. It was retired to the garage for automotive things where its all basically 0v, 12v, or continuity.

    Has anybody done any mods to these? What feature would you add or change? I’d add the continuity beep.

  24. I own one of these (labeled “Digitech” and “QM-1500” and comming in a yellow case) and for my needs (which mostly amount to measuring the value of a resistor or the voltage being delivered by a power supply or whether a diode has blown, just basic stuff for a small hobby breadboard project) it worked great and was cheap enough that I could just grab one and not worry about blowing the budget.

    1. Careful with the Digitech meters. Some of them have a fuse, some of them have a big thick piece of wire soldered in place of the fuse. (No, it’s not the 10A shunt!) I don’t even understand how this would save money! They may have exactly the same part number from Jaycar, the only way to be sure is to open it up. I haven’t tested them myself, but a colleague tells me they are very accurate (for the price!) Juat don’t go near high voltage or current :-)

  25. Thanks for the nice write up!
    I’ve also have got one.

    And an analogue meter, too.
    (Comes in handy for changing values and peaks/dips)

    IMHO, a good electronics hobbyist
    values both types. :)

  26. I have six of these meters located strategically around the home office and the garage, but they aren’t my go-to devices for proper measurements, much like other commenters here. My favourite meter for many uses is still a good old AVO Model 8 though. At least I can never lose that!

  27. These things are indeed a modern marvel and the uncomfortable truth for the snobs out there is that they’re more than good enough for ~90% of projects and general “around the house / workshop” use.

    I’ve got expensive meters and I recognise the various limitations and failings of the DT830, but a meter that’s so cheap you can keep one in every toolbox / vehicle and is utterly disposable / sacrificial is a wonderful and useful thing.

    Much like cheap tape measures and LED torches – I scatter them liberally around my various work places for total convenience when I need to quickly check or test something.

    1. “Much like cheap tape measures and LED torches”

      I now carry a “torch/flashlight” on my belt, and have found it useful at work, shopping, and at home!
      I pull it out more often than I do my SwAK! (Swiss Army Knife)

  28. I use DT9205A with the paper box labeled “DIGITAL”. It has tilt display, ACDC current and voltage up to high amp and woltages you would not want to stick this thing in, and basic capacity measure and hold function. The beeper/diode test is extremely fast and good to use. DT9205M has a two-tone, one for dead short, one for semiconductor-like drop.
    Only those leads suck, the rest is a all-around useable meter that i buy like bread when i see it. Throw one in a car, other in a second car, one in bedroom, one in the garage, one in toolbox and spam them just about everywhere, so you can find at least one every time.

  29. Literally hundreds of thousands of livelihoods depend on this humble gadget. Though-out, the developing world people with some knowledge of electrical circuits who are unemployed set up mobile repairing shops using just a DT830 and a soldering iron. A lot of these shops aren’t even shops, just a makeshift shop on the sidewalk.

    1. Here, (where I work) we throw out customer return DVMs on a daily basis.
      We can’t just dumpster dive, but I have received written permission from the boss to take a few sets of test leads home (to replace the HFT leads).

  30. Ok New Hackaday challenge:
    Hot Rod your DT830.

    Rules:
    Has to fit in the original case or a smaller.
    Need to either improve the precision or add a feature set.
    Budget is limited to the typical price for meter (approx 10$US, we will ignore the free ones from HF).

    1. “Budget is limited to the typical price for meter (approx 10$US […])”

      Nahhh, maybe limit the price of the add on parts to $50!
      That will make it easier to add Wi-fi, Twisted Pair E-net, Bluetooth, USB or RS232, voice, LED strings, sentience…
      B^)

  31. Some idiot probationary “electronics engineer” at my work brought one of these in, and tried to find the polarity of a high amperage -48VDC source with it. It started smoking, he screeched and ran away like a cartoon character seeing a mouse, and then caught fire. Gotta love it.

    1. I was using mine on a comms rack back on the ’90’s. It was the model with the temperature probe instead of the hFE transistor holes (the temperature ones are very rare now.) So I had the temperature probe resting on the rack metalwork measuring air temperature coming out, and then decided to measure the 48V. I hadn’t disconnected the temperature probe, switched to volts, stuck the probes on, and there was a certain amount of sparking from the -48V rail, the probe, etc. But the meter survived! After that I put some heatshrink on the thermocouple.

    1. That would be very hard to do with any device based on the Intersil ICL 7106.

      The 7106 feeds its internal–binary; BCD–data to an internal LCD decoder / driver, and the LCD-drive signals are what emanate from the chip; you have no access to the actual, non-massaged data. Of course, one could always go “in reverse”, and design and build a seven-segment-to-binary DEcoder. If you do, you’ve got way more time, motivation, and energy than most people will ever have.

      You might find it interesting to download a copy of the ICL 7106 / 7107 (the LED-driver version) data sheet, if you can find one, and take a look at that. It’s really a very sophisticated device; what’s even more impressive is that it’s forty, or more, years old,

      1. People did use 7-segment to bcd translators in the early days of small computers. I definitely saw it with calculator ICs but maybe a DVM. Of course, there were other DVM ICs that did not include a decoder, so the data was more easily interfaced with a small computer.

        But yes, the Intersil IC is old enough that it wouldn’t have had a microprocessor, and not enough computers around to see a need for an interface.

        Some old ICs never die, they just see use in ever cheaper products.

        1. One thing I forgot to mention, which would complicate the 7-segment LCD-to-DEcoding process, is that the LCD segment signals are not DC logic levels, but AC signals—as are all LCD segment-drive signals…but this should not constitute anything other than a minor annoyance, if one were truly intent on pursuing this.

          “…But yes, the Intersil IC is old enough that it wouldn’t have had a microprocessor…”

          It had, and has, no need of a microprocessor whatever for its basic functionality. There is nothing a microprocessor could “bring to the party”, as far as A / D conversion is concerned. Admittedly, as for increased capabilities, a small, dedicated microprocessor could certainly provide valuable ancillary services, such as a full data-logging capability. And if the basic design were reworked, that small micro (with enough I/O) could provide conventional logic level binary / BCD, if that were needed, as well as the LCD segment-drive signals.

  32. Seconded, also then possible to display the Bluetooth pairing code on the screen as a voltage ie 1.234 V and repurpose a spare button into the unused socket.
    Many cheap headsets actually have the programming pins enabled and its possible to use a micro as the interface.

  33. I have a bunch of these and one of the most valuable uses I have for them is monitoring voltages (and sometimes currents) in some project I’m trying to debug. Half a dozen little voltage monitors that are continuously connected and operating is SO much nicer than moving from probe point to probe point looking for anomalies.

  34. I noticed an interesting home built electric car conversion in a parking lot, and waited around for the owner to give me a tour of his design.

    It was a no-name hatch back electric kit out of China. The back deck was full of AutoZone 12V lead acid car batteries. Each one had a free Harbor Freight multi meter attached. This dozen meters his quick way to monitor the batteries.

    This was a few years back, but at that time, he told me, he’d run the batteries until they were nearly shot, then return them to AutoZone under warranty, for replacement (“won’t hold a charge”). Appartenly AutoZone later caught on and would only replace batteries if used as intended; for ignition and accessories, but not traction.

  35. Glued 2 together to make a dual meter. One for voltage and one for current. Also used 12 in series across series connected capacitors to check voltage distribution. A bucket of multimeters is a handy thing! Hurrah!

  36. I found the article details about the 7106 interesting.

    I’m still using the Fluke 8020A that I was issued at Digital Equipment Corporation back in 1979. Here’s an interesting thread about the 8020A history, which includes some schematics:

    https://www.eevblog.com/forum/testgear/history-of-the-fluke-8020-series/

    Before that, I used Simpson 260s at the USCG electronics lab in Alexandria, VA.

    There was a huge debate back then about digital vs analog. Being able to watch the speed of the needle was important to many, particularly when checking caps. We could also quickly brush a component with an unknown voltage to see if the needle deflected at all without having to select the right range.

    DVMs brought us more precise power supplies, because now eveyone could document tenths of a volt in the field. I recall fixing quite a few mainframe computer problems by staying clipped to the DC power while tapping the supplies to see if the voltage changed slightly.

  37. I’ve seen them around, and one of my cheaper meters has the same function set, so might be based on the same IC. But in general I have had good results by buying better meters when they go on sale. Eg a “Mastercraft” meter at Canadian Tire that regularly goes for $70 but often goes on sale for $29. I also have a Chinese MASTECH clamp-on meter that is really well-made. My favourite meter is a ~ 25+ year-old Radio Shack clone of the venerable Fluke 77.

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