£2.68 multimeter - Page 1
Forum section: electronics / testgear

author: setq
author_rank: Frequent Contributor
timestamp: September 03, 2016, 09:38:46 pm
content: I'm sure I'll get flamed for a positive review for this but I bought a £2.68 Chinese rebrand DMM from CPC here in the UK as a filler item to get free postage just to see. Turns out it isn't a total piece of crap. I'll probably actually useful for low voltage indication and BJT go/no go tests. Out of the box, it seems to perform EXACTLY the same as my Fluke 8010A. Unlike even some of the high end meters it uses solid tubes for the 4mm sockets rather than pressed metal parts. No floppy leads. Looks a bit funny with Pomona leads coming out of it, as they cost more each than it did.I stuck it across 240v mains on all ranges and settings and only blew the fuse on amps setting. I was hoping it would explode or do something interesting. No banana. I sat there like a kid watching fireworks expecting ooh and ahh but nothing.Good bits: price, seems reasonably robust, 4mm sockets are rock solid, surprisingly accurate, very clear display (better than my UT61E), positive switching action, doesn't turn itself off after 5 minutes or beep at you incessantly like some meters.Crap bits: probes (straight in the bin!), no battery provided, dubious safety at higher voltages, no stand, transistor socket is crap.http://cpc.farnell.com/duratool/d03046/multimeter-digital/dp/IN07220Flame away

author: MosherIV
author_rank: Super Contributor
timestamp: September 03, 2016, 10:01:21 pm
content: You are not going to get flamed by me, dont beleive in itThat is the 'classic' DT830. I have one that is 15 years old, the rotary dial is a bit dodgy now.I am surprised it survived mains on the ohms range, they normally die.Can you do some pics of the insides please?Yes, they can be pretty accurate, at least to sepcification.After all, they are based on a really simple, rock solid, dual slope ADC.They are as good as the resistors that make up the resistor dividers.I would not say it is safe for mains work, watch mjlorton video when he visited the fluke lab to see how badly they can blow under the right circumstances

author: Fungus
author_rank: Super Contributor
timestamp: September 03, 2016, 10:21:02 pm
content: Quote from: setq on September 03, 2016, 09:38:46 pmYes, they're accurate.Quote from: setq on September 03, 2016, 09:38:46 pmI really doubt that. Take the back off and look.Quote from: setq on September 03, 2016, 09:38:46 pm"Fuse"? Really? Pics or it aint true.Quote from: setq on September 03, 2016, 09:38:46 pmDisplays are usually good. The reason it doesn't beep is probably ... it has no beeper.Quote from: setq on September 03, 2016, 09:38:46 pmHere's me testing one for robustness:

author: setq
author_rank: Frequent Contributor
timestamp: September 03, 2016, 10:54:35 pm
content: Nice video.. .it appears mine has an extra board in it!I had to take the back off to install the battery (not included) and replace the fuse. Nudie shot showing fuses (yes two), REAL pp3 clip and real 4mm socket tubes:This must be the luxury version...Then again, note where the calibration pot is supposed to be, replaced by a little fixed resistor.Replacement fuse was yanked out of a UT33A (a real pile of shit for a meter!) and was perhaps unsurprisingly as unlabeled.

author: Fungus
author_rank: Super Contributor
timestamp: September 03, 2016, 11:06:48 pm
content: Quote from: setq on September 03, 2016, 10:54:35 pmDefinitely!Daughterboard, solid tube connectors, fuses, strain relief on the battery wires... is that a PTC and some input protection???

author: Mechatrommer
author_rank: Super Contributor
timestamp: September 03, 2016, 11:18:41 pm
content: Quote from: Fungus on September 03, 2016, 10:21:02 pmreally? pulling on staircases? it like funniest home video. cant you find another fail test other then like what dave did? such as burn test with petrol gas on fluke and that cheapi side by side see which one survive. or blow them with a dynamite

author: RGB255_0_0
author_rank: Frequent Contributor
timestamp: September 03, 2016, 11:25:38 pm
content: If it doesn't survive a SpaceX "launch" it's no bueno.

author: setq
author_rank: Frequent Contributor
timestamp: September 03, 2016, 11:32:25 pm
content: Depends on which SpaceX launchQuote from: Fungus on September 03, 2016, 11:06:48 pmYep. I was surprised.

author: joeqsmith
author_rank: Super Contributor
timestamp: September 04, 2016, 12:00:28 am
content: Much nicer than our free Harbor Freight ones!

author: Macbeth
author_rank: Super Contributor
timestamp: September 04, 2016, 12:14:44 am
content: That looks really good, and clearly worth the extra £1.68 from the usual suspects. One thing I have noticed with the really poor ones are the LCD displays. Not that the ancient 1970's technology is the problem, but the piracy of the display panel itself - it's like old VCR copies of copies of copies - ends up with the shittest possible quality, no sharp edges or lines at all. Despite the insane cheapness of these meters there is someone making $millions. I no longer believe it is China, I think it must be North Korea with their slave labour.The top right corner has room for a trimmer if you really want to calibrate it to super accuracy as 3.5 digits go.

author: Zero999
author_rank: Super Contributor
timestamp: September 04, 2016, 12:25:31 am
content: Lol it's got the fuses specified in AH and mAH on the PCB silk screen.

author: Whales
author_rank: Super Contributor
timestamp: September 04, 2016, 12:33:22 am
content: That's the cleanest looking 830 series DMM I've ever seen. Seems to have half of the normal component count too (no trimpot, for instance). Will this be the new standard model?

author: Macbeth
author_rank: Super Contributor
timestamp: September 04, 2016, 12:36:01 am
content: Quote from: Hero999 on September 04, 2016, 12:25:31 amYou are surely confusing Amp/Hour with AH - Like, AAHHHhhh... Serenity... Chinese mystical healing powers...

author: Brumby
author_rank: Unknown
timestamp: September 04, 2016, 04:11:51 am
content: Seems a shame they put a transistor tester in the thing.Maybe put a sticker over it before Dave sees it.

author: nanofrog
author_rank: Super Contributor
timestamp: September 04, 2016, 04:25:59 am
content: Very similar to the DT830 clones available through Harbor Freight here in the US. That one has better fuses than what I'm familiar with though (2 rather than one, and ceramic bodies rather than glass). I still wouldn't trust it on mains, but they definitely have their uses, such as a glove box DMM (quite useful for this purpose IME).They also make great panel meters.

author: setq
author_rank: Frequent Contributor
timestamp: September 04, 2016, 08:40:36 am
content: Good idea with the panel meter!Quote from: Brumby on September 04, 2016, 04:11:51 amI actually find the transistor tester useful on these. Its pretty good for finding out whether or not a BJT got toasted during repair/design. You can spot a partial failure looking at hFe degredation as well. I dont have the room for a Tek 575

author: daybyter
author_rank: Frequent Contributor
timestamp: September 04, 2016, 11:18:29 am
content: If they would only add a buzzer for continuity to all the 830s...I don't get it, that they still sell some versions without it.

author: MosherIV
author_rank: Super Contributor
timestamp: September 04, 2016, 11:26:59 am
content: QuoteWith the component designation R, it looks like it.Not sure how this helps protect the Ohms range from mains voltge ?The duaghter boards looks like it violates track seperation for high voltage.At least it looks like there is a fuse for the 10A range. Probably soldered lead so that contact resistance does not affect the reading.Edit : Thanks for the picture

author: setq
author_rank: Frequent Contributor
timestamp: September 04, 2016, 12:24:59 pm
content: Indeed. There might be something we can't see on the other side of the board like a hefty diode clamp. I'll grab another one next time I do a CPC order and reverse engineer it properly. I don't want to kill this one as it's turning out to be quite useful!The only real pain is you can't stand it up. Considering gluing two of them to some bent perspex display stuff (with hot snot of course to keep it looking professional)

author: Fungus
author_rank: Super Contributor
timestamp: September 04, 2016, 12:28:51 pm
content: Quote from: setq on September 04, 2016, 12:24:59 pm

author: Fungus
author_rank: Super Contributor
timestamp: September 04, 2016, 12:36:49 pm
content: Quote from: daybyter on September 04, 2016, 11:18:29 amNobody actually pays for them in the USA so they make them as cheap as possible.This one looks like it's actually worth owning. The thing that bothers me the most about these meters is the crappy input posts but this one looks quite solid.They're usually very accurate. Three of four of those around the bench is worth more than a single Fluke 87V when it comes to measuring the basics (Ohms, Volts, Amps).

author: JFJ
author_rank: Regular Contributor
timestamp: September 04, 2016, 01:15:12 pm
content: Quote from: Hero999 on September 04, 2016, 12:25:31 amThe "H" indicates that the fuse should have a High breaking capacity - the fuse needs to remain intact when interrupting a fault current that is many times greater than its normal operating current. In other words, the fuse has to break the circuit without exploding. Hence, the "H" (which is in accordance with IEC 127 marking specifications) signifies that a ceramic fuse is required.

author: Gyro
author_rank: Super Contributor
timestamp: September 04, 2016, 02:48:12 pm
content: The cr*piest thing in there is the Tesco's battery!

author: setq
author_rank: Frequent Contributor
timestamp: September 04, 2016, 03:34:09 pm
content: I stole that battery from the smoke alarm, which I figured I'd need to have taken out for the mains tests anyway.I put a nice GP Ultra one in the smoke alarm later for reference

author: Gyro
author_rank: Super Contributor
timestamp: September 04, 2016, 07:20:51 pm
content: Your world is now a safer place!... Actually probably break-even given your DMM tests.

author: setq
author_rank: Frequent Contributor
timestamp: September 21, 2016, 09:54:11 am
content: Ok so I've been using this solidly for 3 weeks now, well 90% of the time when I'm not using my "better meters" with things like true RMS, frequency and capacitance. Some final notes and nit picky criticisms:1. I measured the input impedance of the thing and it's pretty low, around 1.1M minimum. That's a big problem if you're not aware of it and are poking around high resistances. Almost VOM-like loading thoughts have to go around your head. I'm used to a 10M+ meter so this got me a couple of times.2. The AC volts ranges are shit. The bottom range is 200v. If you're poking around low voltage AC circuits this gives you no resolution.3. It's never in the right place and doesn't stay put. This is quite frustrating. A few times it has bailed off the edge of the table and taken a few things with it off a breadboard or pulled the breadboard onto the floor. My Fluke and Uni-T meters are 10x heavier so this never happens.4. Burden voltage in 200uA-2mA ranges isn't too bad at around 0.5v.5. Transistor socket is rubbish. No contact half the time. I went through a box of germanium transistors I've got floating around and it was hopeless. I resorted to building a simple deadbug test rig with a ZIF socket from the junk box in the end.6. Smells a bit funny after a couple of minutes if you stick 2A through it on 5A range. I wouldn't use this for more than 1A if I'm honest.7. The 4mm sockets are still rock solid. These should be on EVERY meter.8. I got it to be a null meter to measure inductance using a simple oscillator and bridge I made. I could probably eviscerate it and stick it in a hammond box and turn this into a dedicated inductance bridge and be cash up on a moving coil or meter module.Altogether minor problems and still good value for £2.68.

author: Fungus
author_rank: Super Contributor
timestamp: September 21, 2016, 10:02:50 am
content: Quote from: setq on September 21, 2016, 09:54:11 amYep.For basic measurements of DC volts and Ohms those meters work just fine. Well worth having around the bench for when you need an extra meter.