Is this the bottom of the cheap multimeter heap? - Page 1
Forum section: electronics / general

author: slburris
author_rank: Frequent Contributor
timestamp: July 15, 2010, 09:03:53 pm
content: Here in the US, Harbor Freight has put a multimeter from Cen-Tech on sale for $1.99.Down from the usual price of $9.99.http://www.harborfreight.com/7-function-digital-multimeter-90899.htmlIt features a "fuse and diode" protected circuit :-)I'm tempted to get one just to take it apart and see what $1.99 buys you...Scott

author: Rhythmtech
author_rank: Regular Contributor
timestamp: July 15, 2010, 09:10:01 pm
content: A friend of mine is installing something similar as the voltage readout in his ATX PSU bench top conversion

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 15, 2010, 09:27:01 pm
content: Looks like they'll be perfect for a homemade bench power supply or component test jig. Or even as a digital panel meter.

author: saturation
author_rank: Super Contributor
timestamp: July 15, 2010, 09:32:14 pm
content: Harbor Freight, Walmart, Sam's Club and other sell some DMM so dirt cheap, they are better than buying panel meters from whomever. At the minimum its Vdc shouldn't be worse than a panel meters.

author: easilyconfused
author_rank: Regular Contributor
timestamp: July 15, 2010, 11:47:02 pm
content: Quote from: slburris on July 15, 2010, 09:03:53 pmAs crummy as it probably is-- it serves to illustrate why there are no jobs in America. There's not one company in the US that could produce something like that for less than $30. By the time we satisfy OSHA, pay minimum wage, pay corporate taxes, buy product-liability insurance, provide health-care, and so forth, it just can't be done. Meanwhile, the goods we order are manufactured on a dirt floor. Our ideal country provides for everything but a job.

author: saturation
author_rank: Super Contributor
timestamp: July 16, 2010, 01:01:11 am
content: Or whomever is making it in China is either efficient like we can never believe, the product is being dumped, its a loss leader to get you into the store, or its overstock like you would get in a dollar day buy.China subsidizes many of their industries, its more accepted given their socialist roots. For example, mail to the USA is nearly free, its the same cost as their local mail. So this encourages a lot of direct shipping from Chinese merchants to 1st world consumers that you see on eBay.I have bought many an electronic gadget for $1 at eBay with free shipping.For example, this USB cable:http://cgi.ebay.com/USB-DATA-SYNC-CABLE-WIRE-CORD-APPLE-IPHONE-3G-NEW-/250665636432?cmd=ViewItem&pt=PDA_Accessories&hash=item3a5cd61250Quote from: easilyconfused on July 15, 2010, 11:47:02 pm

author: slburris
author_rank: Frequent Contributor
timestamp: July 16, 2010, 03:42:50 am
content: I never though about using these as cheap displays.I could create something similar to the Simpson clock:http://hackedgadgets.com/2010/06/23/multimeter-clock-styled-after-the-simpson-260-multimeter/If I threw in a month-day-year display too, I'd need 6 multimeters, fora total cost of $12. Hmm, maybe I should do this.Scott

author: charliex
author_rank: Frequent Contributor
timestamp: July 16, 2010, 04:09:20 am
content: we bought a bunch of them for our hackerspace, they're worth what you pay for. theres a couple in bits if people want to see the insides.

author: MrPlacid
author_rank: Frequent Contributor
timestamp: July 16, 2010, 04:12:20 am
content: Quote from: slburris on July 15, 2010, 09:03:53 pmThis price range is their usual price $1.99-$3.99. I got 3 of them and they works. I'll recommend them to any beginning hobbyist who's low on cash. I've stuck them into main and they work, but I highly recommend against playing with mains using them. It's really SCARY!!!If you're gonna spend significant money don't waste them on cheap multimeters. But this isn't cheap, it's dirt cheap

author: TheWelly888
author_rank: Frequent Contributor
timestamp: July 16, 2010, 08:42:03 am
content: One guy reviewing that meter said, "I've had probably 30 of these over the past 5 years." and still gave it 5 stars!That says it all really.....

author: saturation
author_rank: Super Contributor
timestamp: July 16, 2010, 10:52:00 am
content: Why not do an electronic test for us, comparing it against your better meter?That is check Vdc and ac, mA etc., I wouldn't drop the thing it looks like it won't hold up to much abuse but if its electrically sound, it should be good for CAT I level work.If any of these are true, compare it to Dave review, the specs aren't shabby at all. From the user manual at the HF site see attachment.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: July 16, 2010, 12:13:56 pm
content: Basically, this meters can only be compared between its other ..If they agree in all settings , it will be a miracle ..

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 16, 2010, 12:38:12 pm
content: i had this similar appearance and cost DMM years ago which what is left today is its dead body in my junk box. its not designed to last, but when they were, they works properly. usually, the lcd contact to the pcb is by some cheap carbon strip/array, that can get easily damaged when you detach n re-attach to the pcb just couples of time. if i want to give an advice, i suggest you get something just priced a little bit higher (but still cheap) like $10-20 if what you expect is a longer life DMM. i missed them, but... i'm not going to buy them anymore

author: Rhythmtech
author_rank: Regular Contributor
timestamp: July 16, 2010, 02:16:21 pm
content: Do a Pros and Cons:Pros:1. Price2. Local availability coupled with price - you don't have to wait for it to show up if there is a Harbor Freight in your area3. Probably works well enough for most simple low voltage stuff4. If it gets crushed in your toolbox, grab bag, glove compartment, or pocket who cares5. Passing them out to people, to show them what they can get by with but why they need a good meter is cool of you.Cons1. Leads are probably not CAT ? rated and the meter inputs say CAT II, but I wouldn't trust my hand to it. So no home electrical work.2. You would need to be looking for flaky readings all of the time, just in case.3. Not auto rangingAs far as being made in the USA. I am happy we don't manufacturer anything this crappy; then watch people buy it below cost, only because of the cost. Hopefully a US shipping company got paid to bring it into the country, Harbor Freight is owned by Central Purchasing which is a privately owned company based in Camarillo, CA. I suppose it would be possible for them to be owned by the Chinese and just a forwarding address is in CA, but more than likely they are not. Not making a $1.99 multimeter purchase is not much of a statement in opposition to Chinese manufactured goods. It's when it is cheaper to ship ore from Australia to China to become steel and then is shipped to the US and Mexico to produce goods to be sold in the US instead of using steel that is at least already on our continent that is really hurting industry.

author: Zero999
author_rank: Super Contributor
timestamp: July 16, 2010, 04:38:21 pm
content: I've got one of those DVMs.The build quality is poor - you get what you pay for. It worked for a few years then broke, it's still in a draw along with spare parts. I can't see myself buying another, unless I need to do a high risk job where the meter could easily get lost, broken or stolen.The leads certainly don't meet necessary approvals for carrying out work on voltages in the UK - the probes should be sheathed with only a few mm at the tips exposed.

author: slburris
author_rank: Frequent Contributor
timestamp: July 16, 2010, 06:34:43 pm
content: I thought Harbor Freight's story is they got started buying shippingcontainers full of tools that had been abandoned for some reason, and resellingthe contents?Scott

author: Rhythmtech
author_rank: Regular Contributor
timestamp: July 16, 2010, 06:40:12 pm
content: Quote from: slburris on July 16, 2010, 06:34:43 pmSeems reasonable, does that mean they are indeed a US company and have not been bought out or otherwise? Things are not always what they seem now days...Apparently containers fall from ships in rough seas occasionally into the drink. Some salvage companies retrieve their content (usually much more valuable than tools).

author: TheWelly888
author_rank: Frequent Contributor
timestamp: July 16, 2010, 08:21:34 pm
content: ^^^You may have heard the English phrase "fallen off the back of a lorry" to describe rather dodgy goods.So "fallen off the side of a boat" should apply here?

author: MrPlacid
author_rank: Frequent Contributor
timestamp: July 17, 2010, 03:35:35 am
content: Quote from: slburris on July 16, 2010, 06:34:43 pmI don't think this is the case. I live near one of their warehouse, not the Harbor Freight store. That place is gigantic. You can fit several wholesales in there. So I think they don't buy abandoned merchandises, but purchased chinese tools in large quantity. If Harbor Freight don't sells those chinese tools for the chineses, I doubt anyone who is willing.

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 17, 2010, 04:35:46 am
content: Quote from: slburris on July 16, 2010, 03:42:50 amhttps://www.eevblog.com/forum/index.php?topic=748.0On a related note, I got a few free calculators today at a VMware event (along with a free computer mouse, some free snacks, and a free viewing of Inception as well...). I already turned one into a stopwatch by adding a PCB from a broken analog clock, two resistors, a transistor, and a switch. I just tested the timeout on another one and it's roughly 10 minutes (a test of patience!), so I'll probably make it into an event counter by adding a reed switch.Never expect one of those free calculators to even come close to a TI-89 but an experienced electrical engineer (who obviously already owns at least one good meter and one good calculator, likely more) would find one of those cheap calculators more useful than a cheap multimeter.

author: slburris
author_rank: Frequent Contributor
timestamp: July 18, 2010, 03:58:53 am
content: I went and picked one of these up for $1.99.Just for fun, I tried a few measurements and compared to myFluke 87-V.Using a 500Khz 0.05% resistance standard:87-V: 500.1 KCen-Tech: 496KThen I measured a random button cell I had on the bench:87-V: 1.424vCen-Tech: 1.41v on 20v range: 848mv on 2000mv range (!)Then I took it apart. Build quality of the PCB was surprisinglygood for a $2 meter. I got one of the Colorful batteries.Input jacks were solid, instead of the slotted ones Dave dislikes.I'm not going to plug this meter in the mains, that's for sure.But I will toss it in my car to use in case I break down on the road.Scott

author: saturation
author_rank: Super Contributor
timestamp: July 18, 2010, 12:04:55 pm
content: This is what all of Dave's reviews have shown, my personal observation of lower cost DMMs, its that they can read very well in some areas [ competitive to expensive meters ] and not in others. You also pay a lot most for robustness and electrical protection.It then comes down to trust, can you trust the cheapo to measure correctly on all its functions? Also will it hold up to environmental changes and drops, the last thing you need is a OK after a checkout, its stored in a case, and when you pull it to use, it reads wrong. As measurement can decide whether a device gets serviced, a part need be bought, the device is trashed ... decisions that could cost a little or a lot of money.I'm surprised by the wrong reading on the 2V range, that should be the more accurate one! It suggests there is a problem with a resistance divider or there is something funky with the 9v battery. You could give the PCB a once over a look for dirt or if its not autoranging check the range switch for dirt or poor contact, that could add a substantial series resistance.I tend to use these cheapos for circuit monitoring, you can buy a few of these to plug into a circuit so you see test voltages in multiple areas at once, rather than taking a single DMM and checking test points one by one. But it has to pass a calibration test against a good meter before relying on those readings.Quote from: slburris on July 18, 2010, 03:58:53 am

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: July 18, 2010, 01:58:51 pm
content: Quote from: slburris on July 18, 2010, 03:58:53 amScottThe most important in electronics , are the quality of the chip it self ...The same chip , that has created correctly ( Grade A ) , it could be found inside in a Fluke meter !!The same chip, that has small errors ( Grade B ) can be found in the 50$ multimeter 's .The same chip, that has large errors ( Grade C ) can be found in the 2$ multimeter 's .We have use to examine devices by their look , but the most important ,its their hart .. if this are an healthy one , the rest can have an lesser importance .If , from time to time , I look as an UNI-T fun-boy , its because I have realize ,that they use only " or mostly " healthy chips , plus an acceptable build quality . ( exterior )

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 18, 2010, 03:05:14 pm
content: i never heard of the same chip got Grade A,B or C like the fruits or other foodswhat i usually see is that different DMM line will use different chip.

author: saturation
author_rank: Super Contributor
timestamp: July 18, 2010, 03:25:36 pm
content: In otherwise identical CPUs with different clock speeds, if a high speed one fails a quality check, it will be rebadged as a low speed CPU.This was done in the past, but I don't know if its still common practice.Other quality checks are statistical when batch tests are done of the operating parameters of any device. US Military grade is the highest, typically 100% or 99.99%, B grade may be 99% of samples test in-spec, C, 95% etc., usually the C grades are not sold to manufacturers but given to hobbyist market, or sold in unmarked packaging in 'grab bags' like Jameco does.Quote from: shafri on July 18, 2010, 03:05:14 pm

author: jimmc
author_rank: Frequent Contributor
timestamp: July 18, 2010, 08:50:36 pm
content: Almost all of these cheap meters are based on the ICL7106 chip; for a typical circuit see...http://www.hobby-hour.com/electronics/dt830b-digital-multimeter.php(link at end of 3rd paragraph)Quality varies greatly, I have had some with no fuse and no trimmer for calibration!Jim

author: Chris_R
author_rank: Contributor
timestamp: July 19, 2010, 01:07:56 am
content: I was going to come in here to gawp at how terrible the multimeter was but then I realised I've seen this before sold in Maplins in the UK. I only remember it because they were selling them instore buy one get one free.I mean who would need one of these crappy meters, let alone two!http://www.maplin.co.uk/Module.aspx?ModuleNo=37279

author: MrPlacid
author_rank: Frequent Contributor
timestamp: July 19, 2010, 07:50:09 am
content: By the way ,2 years ago (or more) Fry's Electronics had in the paper selling an analog multimeter with mail in rebate for the same price. So the cost of the meter was the tax. I played with it for a while and with simple 9volt battery on different range and pop went the fuseSo I think that would be the bottom of the cheap multimeter.

author: xrunner
author_rank: Super Contributor
timestamp: August 13, 2024, 10:39:11 pm
content: I needed a cheap DMM for my shed, so while at Harbor Freight I picked up the ubiquitous 7 Function DMM. This thread was started in 2010 so 14 years later we have this PCB. There is a pic at the beginning of this thread of the PCB from 2010. Interestingly it has the same brand of battery, a very "colorful" one indeed, nearly the same art work as 14 years ago.As for performance it's not bad. Some testing shown in the pics. For $7 hey it works good enough for common uses around the house.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: August 14, 2024, 01:09:29 pm
content: International Postal Rates are set by the Universal Postal Union and are set to be advantageous to third world developing countries.https://en.wikipedia.org/wiki/Universal_Postal_UnionQuote from: saturation on July 16, 2010, 01:01:11 am

author: amyk
author_rank: Super Contributor
timestamp: August 15, 2024, 01:40:19 am
content: The infamous DT830... there are actually many variants, some better than others.https://www.eevblog.com/forum/testgear/t21463/https://www.eevblog.com/forum/testgear/trashy-meters-redux/https://www.eevblog.com/forum/chat/which-multimeter-or-company-started-830-design-case-that-is-so-widely-copied/https://hackaday.com/2020/09/24/in-praise-of-the-dt830-the-phenomenal-instrument-you-probably-dont-recognise-for-what-it-is/

author: tom66
author_rank: Super Contributor
timestamp: August 15, 2024, 07:51:19 am
content: There's nothing all that wrong with one of these cheap multimeters provided they don't go anywhere near mains voltage or high energy things. For messing around with Arduino circuits they're fine... maybe buy a second to double check any dubious readings...

author: EPAIII
author_rank: Super Contributor
timestamp: August 15, 2024, 09:12:59 am
content: At $9.99 it is a great, profitable sale. HF loves it.$1.99 is probably what they pay for them, including shipping from China. So, not a loss-leader but probably a break-even-leader to get you into the store.I have or have had at least two of them. One is dead. The other still works. I am not hard on equipment. That should tell you something.Quote from: saturation on July 16, 2010, 01:01:11 am

author: Gyro
author_rank: Super Contributor
timestamp: August 15, 2024, 09:30:14 am
content: A lot of those little meters give the impression that the designers actually tried to do a good job for the price. I have a tiny Skytronic one (a little different because it takes a smaller 12V battery) which is a perfect pocket meter for quick checks on potential bargain finds. It even has the correct CAT rating on the front!https://www.eevblog.com/forum/chat/what-did-you-buy-today-post-your-latest-purchase!/msg4160605/#msg4160605

author: rhb
author_rank: Super Contributor
timestamp: August 15, 2024, 12:21:12 pm
content: I have a slew of them all over the place, some bought for $1.99 and some free. They are my standard go to. The. 3457A, 34401As and 3478As sit on the bench for fussy stuff. The 3458A is awaiting repairs.They occasionally die, but the fixes are pretty trivial. Broken 9 V connector being the leading cause. Calibrated they are 0.1% or better. I use them for car and household repairs and testing battery cells. I have a great many task specific toolboxes. All the tasks that might need a DMM have one in the toolbox.Love them!Have Fun!Reg

author: fzabkar
author_rank: Super Contributor
timestamp: August 15, 2024, 06:36:33 pm
content: I see that some people have mentioned using these DMMs as panel meters. Are they using a battery as the power source, or have they found some way to utilise the power source that they are measuring?

author: ledtester
author_rank: Super Contributor
timestamp: August 15, 2024, 07:32:35 pm
content: Does anyone have a guide to making these meters more accurate - perhaps by replacing the on board discrete parts?

author: BILLPOD
author_rank: Frequent Contributor
timestamp: August 15, 2024, 07:51:54 pm
content: Good Morning Slburris, At the Harbor Freight link you posted, the cheapest multimeter I could find was $6.99, and it looks like the same 'cheapy' they have always had. Were you looking at a special sale price?

author: floobydust
author_rank: Super Contributor
timestamp: August 15, 2024, 08:01:01 pm
content: Quote from: fzabkar on August 15, 2024, 06:36:33 pmMultimeter input COM(-) is not BATT(-) and you can damage the IC getting that wrong. So for panel meter use, you need isolated power, or have to make sure the common-mode voltage is reasonable. But there's no protection parts there, no coverage for CM voltage going awry, the IC will get blown up then.A problem with these cheap DT830 multimeters is the protection components are usually left out, not populated. It depends on how cheap the build is. You have to use your eye and look for them.A common happening is having it on Ohms but connecting to voltage like 24V. No PTC and maybe that lightbulb will cover it, but generally it will damage the DMM IC in these.

author: tooki
author_rank: Super Contributor
timestamp: August 15, 2024, 08:06:24 pm
content: Quote from: BILLPOD on August 15, 2024, 07:51:54 pmDude, it was a price (whether promotional or regular) 14 years ago. You can’t expect it to be the same today!

author: tooki
author_rank: Super Contributor
timestamp: August 15, 2024, 08:09:17 pm
content: Quote from: ledtester on August 15, 2024, 07:32:35 pmThey are already about as accurate as that fundamental multimeter design is capable of. Youmightbe able to eke out a smidgen better long-term stability, but you could just twiddle the calibration pots every 5 years and do just as well.

author: tom66
author_rank: Super Contributor
timestamp: August 15, 2024, 09:51:28 pm
content: Quote from: ledtester on August 15, 2024, 07:32:35 pmYou can buy a significantly more accurate meter for about $20. How much do you really value your time?I suspect the inexpensive internal voltage reference in the main IC and the tempco of the cheap divider resistors will limit any accuracy improvement. Short of replacing most parts, you're not going to improve the performance noticeably.

author: xrunner
author_rank: Super Contributor
timestamp: August 16, 2024, 01:09:13 am
content: Getting back to the original question for a second: I tried to see if there were deals on Amazon or AliExpress for a DMM less than what I paid for the HF DMM ($7).Searching Amazon for the cheapest DMM, I couldn't get below around $9. But in the range $9 to say $15 there were some decent looking meters for casual use.Regarding AliExpress, I am not a member yet. But when searching for DMMs there it gave me offers characterized as a "Welcome Deal". Taking that into account I could apparently get a very capable looking DMM from ANENG for a mere $0.99. Tempting ...

author: rhb
author_rank: Super Contributor
timestamp: August 18, 2024, 09:16:13 pm
content: Quote from: tom66 on August 15, 2024, 09:51:28 pmThey are as accurate as they have the ability to display. For $2 or Free they were a steal. The more recent ones I got before they stopped giving them away don’t have a trimmer for setting it to a voltage reference. A more serious limitation is the 1 MEG input impedance. For better, spend more.But they are decent DMMs for general household work or as dedicated V & A meters on a low budget lab bench.Have Fun!Reg

author: Brumby
author_rank: Unknown
timestamp: August 19, 2024, 12:04:22 am
content: Quote from: amyk on August 15, 2024, 01:40:19 amIndeed. I had some fun with my <$10 DT830 a few years ago.The new front panel artwork:The story of how it began and the iterative process of development is documented here:https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg1689437/#msg1689437