Author Topic: £2.68 multimeter  (Read 8841 times)

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Offline setq

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£2.68 multimeter
« on: September 03, 2016, 09:38:46 pm »
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/IN07220

Flame away  >:D
 

Offline MosherIV

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Re: £2.68 multimeter
« Reply #1 on: September 03, 2016, 10:01:21 pm »
You are not going to get flamed by me, dont beleive in it  :-+

That 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
 

Offline Fungus

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Re: £2.68 multimeter
« Reply #2 on: September 03, 2016, 10:21:02 pm »
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.

Yes, they're accurate.

Unlike even some of the high end meters it uses solid tubes for the 4mm sockets rather than pressed metal parts.

I really doubt that. Take the back off and look.

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.

"Fuse"? Really? Pics or it aint true.

Good bits: 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.
Displays are usually good. The reason it doesn't beep is probably ... it has no beeper.

seems reasonably robust

Here's me testing one for robustness:


 

Offline setq

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Re: £2.68 multimeter
« Reply #3 on: September 03, 2016, 10:54:35 pm »
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.
« Last Edit: September 03, 2016, 11:05:53 pm by setq »
 

Offline Fungus

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Re: £2.68 multimeter
« Reply #4 on: September 03, 2016, 11:06:48 pm »
This must be the luxury version...

Definitely!

Daughterboard, solid tube connectors, fuses, strain relief on the battery wires... is that a PTC and some input protection???  :scared:


« Last Edit: September 03, 2016, 11:11:02 pm by Fungus »
 

Online Mechatrommer

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Re: £2.68 multimeter
« Reply #5 on: September 03, 2016, 11:18:41 pm »
testing one for robustness:
:palm: really? 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  :-+
if something can select, how cant it be intelligent? if something is intelligent, how cant it exist?
 

Offline RGB255_0_0

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Re: £2.68 multimeter
« Reply #6 on: September 03, 2016, 11:25:38 pm »
If it doesn't survive a SpaceX "launch" it's no bueno.
Your toaster just set fire to an African child over TCP.
 

Offline setq

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Re: £2.68 multimeter
« Reply #7 on: September 03, 2016, 11:32:25 pm »
Depends on which SpaceX launch  ;D

This must be the luxury version...

Definitely!

Daughterboard, solid tube connectors, fuses, strain relief on the battery wires... is that a PTC and some input protection???  :scared:

Yep. I was surprised.
 

Offline joeqsmith

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Re: £2.68 multimeter
« Reply #8 on: September 04, 2016, 12:00:28 am »
Much nicer than our free Harbor Freight ones!   
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline Macbeth

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Re: £2.68 multimeter
« Reply #9 on: September 04, 2016, 12:14:44 am »
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.
 

Offline Zero999

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Re: £2.68 multimeter
« Reply #10 on: September 04, 2016, 12:25:31 am »
Lol it's got the fuses specified in AH and mAH on the PCB silk screen.
 

Offline Whales

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Re: £2.68 multimeter
« Reply #11 on: September 04, 2016, 12:33:22 am »
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?

Offline Macbeth

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Re: £2.68 multimeter
« Reply #12 on: September 04, 2016, 12:36:01 am »
Lol it's got the fuses specified in AH and mAH on the PCB silk screen.
You are surely confusing Amp/Hour with AH - Like, AAHHHhhh... Serenity... Chinese mystical healing powers...  :-DD  :bullshit:
 

Offline Brumby

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Re: £2.68 multimeter
« Reply #13 on: September 04, 2016, 04:11:51 am »
Seems a shame they put a transistor tester in the thing.

Maybe put a sticker over it before Dave sees it.
 

Offline nanofrog

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Re: £2.68 multimeter
« Reply #14 on: September 04, 2016, 04:25:59 am »
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.  :o  >:D
 

Offline setq

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Re: £2.68 multimeter
« Reply #15 on: September 04, 2016, 08:40:36 am »
Good idea with the panel meter!

Seems a shame they put a transistor tester in the thing.

Maybe put a sticker over it before Dave sees it.

I 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 ;)
« Last Edit: September 04, 2016, 08:43:19 am by setq »
 

Offline daybyter

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Re: £2.68 multimeter
« Reply #16 on: September 04, 2016, 11:18:29 am »
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.
 

Offline MosherIV

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Re: £2.68 multimeter
« Reply #17 on: September 04, 2016, 11:26:59 am »
Quote
  is that a PTC and some input protection?
With 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  :-+
 

Offline setq

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Re: £2.68 multimeter
« Reply #18 on: September 04, 2016, 12:24:59 pm »
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 ;))
 

Offline Fungus

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Re: £2.68 multimeter
« Reply #19 on: September 04, 2016, 12:28:51 pm »
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 ;))




 

Offline Fungus

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Re: £2.68 multimeter
« Reply #20 on: September 04, 2016, 12:36:49 pm »
I don't get it, that they still sell some versions without it.

Nobody 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.  :popcorn:

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).
 

Online JFJ

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Re: £2.68 multimeter
« Reply #21 on: September 04, 2016, 01:15:12 pm »
... it's got the fuses specified in AH and mAH on the PCB silk screen.

The "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.
 
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Offline Gyro

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Re: £2.68 multimeter
« Reply #22 on: September 04, 2016, 02:48:12 pm »
The cr*piest thing in there is the Tesco's battery!  :D
Chris

"Victor Meldrew, the Crimson Avenger!"
 

Offline setq

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Re: £2.68 multimeter
« Reply #23 on: September 04, 2016, 03:34:09 pm »
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 :)
 

Offline Gyro

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Re: £2.68 multimeter
« Reply #24 on: September 04, 2016, 07:20:51 pm »
Your world is now a safer place!  :phew:

... Actually probably break-even given your DMM tests.  :)
« Last Edit: September 04, 2016, 07:22:24 pm by Gyro »
Chris

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