Are very cheap DMMs worth buying?

[Joe_Lorenz]

For outdoor and field use (e. g. what's wrong with that horse fence energizer) it is a good idea to have some cheapo DMMs at hand (or in the car, in the stable, ff.) as sometimes you are literally covered with mud and moisture, once in a while ending in a total write-off.

I do not have a Fluke or so in my shop. A Goerz Metrawatt Symetra D Bench Nixie Multimter from 1970 and some analogue instruments have been ok by now. My favourite is a MIL ME-9E/U multimeter with MX-815A/U high voltage multiplier kit: The Weston instrument is great, and the unit itself will last forever. If you want to say so, that was a cheap meter, too: A fiver at a flea market. The seller wanted to get rid of that huge clunker ...

Joe

[PETERg0rsq]

This discussion has been had many times before.

In my (unpopular) opinion I would not recommend a cheap DMM for a novice (nor an expensive professional one either)!



A novice is more likely to make a mistake while probing, and a cheap one would be very unforgiving, potentially dangerous. Particularly with probes and protection. A fluke, or similar, isnt going to explode when connected to the mains in ohms mode, or weld its self the transformer if left in 10Amp range!

You say if used within its limits!, but would a novice understand its limits?

Would a novice understand if the DMM started giving erroneous readings?

I would always recommend a used quality DMM over a new cheap one even if it means spending £50 or more. A good used fluke is going to be a better option than a new ali-express offering.

Your first DMM could be seen as an investment in your hobby, and should last many years.

There are some decent low end new meters, but it is pot luck with the copying and cloning on world market places.

For more experienced users, yes ignore the above, you understand what you are doing and the risks, but not for a novice!

[Bazz4CQJ]

Yes... I guess you could ask yourself, "Do I want my [young son/daughter]" using a budget meter?

But, are the failure modes of these latest meters necessarily more dangerous than, say, an AVO Mulitminor (no fuses and a meter shunt etched on copper-clad board) or the Proskit analogue, which is still on sale after several years? The latter measures 10amps, but only for 15 seconds (that applies to many DMMs). My first meter (early 1960's) was a small analogue meter from Eagle. No fuses at all and really quite thin leads supplied for use at 1000V.

Is some of the angst about these meters, especially on YouTube, because they are made in China (not popular everywhere), they are really inexpensive and may actually be quite usable?

For the first time ever, I blew the 11A fuse in my Fluke recently (it's rated for continuous use at 10A); perhaps a sign of advancing years (of the operator - not the meter) ? The meter is OK.

I will look at the SZ305 and try to judge it impartially.

B

[Richardgr]

From the replies here, the consensus would appear to be 'horses for courses'. If you are tinkering on an old PA and could encounter 600V+ voltages, then it needs to be a professional quality instrument.
I never use a meter to measure current, I would always measure a voltage drop over a resistor. Would be interested if anyone does use a meter to measure current?

[kalee20]

Originally Posted by Richardgr

I never use a meter to measure current, I would always measure a voltage drop over a resistor. Would be interested if anyone does use a meter to measure current?

Oh yes! I was measuring magnetising current versus volts for a transformer recently. Two DMM's, one measuring current, one measuring applied voltage.

And also fairly recently, assessing the regulation of a power supply with varying load. Three DMM's, one measuring input voltage (to twiddle the Variac so it's constant); one measuring load current; one measuring output voltage.

[factory]

Where they are made is irrelevant, but when the front of the meter claims it has a fuse, when it doesn't is fraud, as is overeading by 20% when it claims say 2%.
None of the old analog meters claimed none existant fuses did they?

Even buying a used handheld DMM in good condition working order can be difficult, last one I bought had been ruined by leaky batteries. The old DMM I had been using has started giving problems, resistance measurement had gone intermittent on the lowest range.

And yes I do measure current, often when testing components out of circuit and to compare & find suitable replacements.

Secondhand AVO8 can have problems too, first one had open movement, second one out of spec on the HV range, third one had good HV range but eventually noticed the 10A range was open circuit.

David

[Nickthedentist]

I use my Fluke to measure current all the time. The 20A range is also great for checking the condition of dry cells - family members (not just the children!) have a habit of mixing old with new with partially-used ones.

[McMurdo]

I use a cheap multimeter for around the house and am glad it's with me. I check batteries, continuity of leads, that sort of thing. But it's still from a reputable supplier and has all the approvals..in case I need to probe a 13A socket, for example.

Having been led annoyingly astray by cheap and unreliable (under a tenner) meters for even menial tasks (say using a colleagues) I can't recommend them.
Here's my cheapie:

[stuarth]

I’m not against low cost meters, but for a general purpose meter, particularly as a first meter, ie one being used by someone inexperienced, I worry a bit about recommending the very cheapest meters when these days you can get something much more robust and idiot proof in the £10 to £15 range.

Even for experienced users, for a few extra pounds can get you a much better meter, eg 10Meg input impedance instead of 1Meg, 6000 or 4000 count instead of 1999, resistance measurements to 20Meg not 2Meg, auto ranging, 2 x AAA cells not a PP3 (this would negate the cost difference after a couple of battery changes, etc.

Not quite sure how an inexperienced user would know how to choose a meter, I would look for a CAT III 600V rating from a reliable source or brand name, the Lidl meter mentioned in Post 1 has a TUV Rhineland logo and reference number so I think that’s genuine, and the Triplett meter - I don’t think Triplett would risk their reputation and put CAT III 600V and the Intertek logo on if they weren’t genuine.

As an example, I’d trust suppliers such as CPC Farnell, they offer many low cost multimeters, including the D03046 at £3.74 which I wouldn’t like to hand hold while probing the mains, and the Multicomp Pro MP730425 at £11.94 with a CAT III 600V rating, this seems to be, like the Triplett MM200, a rebadged UniT UT 123. From the meters I’ve seen on sale recently, I’d say the use of a PP3 battery is the first warning sign…..

Stuart

[paulsherwin]

I think the supply voltage depends on the chip the meter is built around.

[stuarth]

Maybe the very cheap meters are using an old design/process chip, and the better meters use a more modern chip?

[Keith956]

I have a couple of cheapie meters, but the build quality does not lead one to believe they were designed to be failsafe. They don't get used on mains wiring.

I am reminded of what an uncle in the aircraft industry said once: "if you think safety is expensive, wait until you have an accident".

[paulsherwin]

Originally Posted by stuarth

Maybe the very cheap meters are using an old design/process chip, and the better meters use a more modern chip?

Apparently the DT830s use a chip derived from the old Intersil ICL7106 design, which has indeed been around for a long time: https://www.alldatasheet.com/html-pdf/72687/MAXIM/ICL7106/126/1/ICL7106.html

[Seanyboy]

Yeah - totally agree, spend your money on a quality used multimeter (but don't go mad) -

You really do get what you pay for.

It's fine having an odd cheapo one kicking around at home (asIi have) for checking if a battery is flat and the likes but not for serious measurement tasks

I've owned Flukes for the last 30 years and in that time have only ever purchased 3 - one of which got left on a window sill for a week in the rain which is the only reason it got replaced! They're pretty bomb proof and you'll get your money back over time

My colleagues (in the security industry - Intruder alarms and the likes) go through the cheap ones like a bag of toffees... most are totally fried from testing DC current incorrectly (They just stick the leads straight across the terminals demanding full supply current instead of measuring in series) - and vaporising the PCB that feeds the circuitry internally

They spend about £10 to £15 max each a time, but each engineer has 2 or 3 a year (£45 a year over 10 years - £450) whilst a decent Fluke etc used would be £70 - £150 and would never let you down

However....

Ironically, I wouldn't trust a single one of them with a quality multimeter as it would get left behind, wrecked or stolen as they don't respect a quality piece of test equipment - so in the bigger world of 'disposable' multimeters I can see how they fit into the bigger picture.

[QQVO6/40]

Greetings all.
I can vouch for the safety capabilities of fluke digital meters.
some years ago I worked in an open cut coal mine and on some pretty big gear.
A fellow electrician had a brain fade and put his Fluke 77 across 6,600 Volts on the primary cable side of the supply. The supply breakers are set for 1,200 Amperes.
No bang! His meter did not spew flames and smoke! Just nothing!
We did note the old adage. It didn't let the smoke out but kept it inside and the LCD window went all Smoky grey inside.
Never worked again and inside the meter was completely fried.

The good old days!
Tales from the past from working on big stuff.
Cheers all.
Robert.

[The Philpott]

Just as well the guy had a decent meter, as i think the Australian mines were known for the growth of Tetraamine Copper Nitrate on electrical terminals!

Dave

[fetteler]

To give a simple answer to the OP's question: Yes!

Steve.

[ortek_service]

Originally Posted by stuarth

>>
>>
From the meters I’ve seen on sale recently, I’d say the use of a PP3 battery is the first warning sign…..
Stuart

I presume you meant to say not using a PP3 battery?
- As all the Fluke's I've seen and most other DMM's do.

It's only the slim ones - often with short captive leads - that tend to use AAA or coin cells (Or the probe type ones). With there being a Tandy Micronta one as far back as the 80's.
But they do fit in your pocket, so can be handy to keep on you.

[ortek_service]

Originally Posted by QQVO6/40

Greetings all.
I can vouch for the safety capabilities of fluke digital meters.
some years ago I worked in an open cut coal mine and on some pretty big gear.
A fellow electrician had a brain fade and put his Fluke 77 across 6,600 Volts on the primary cable side of the supply. The supply breakers are set for 1,200 Amperes.
No bang! His meter did not spew flames and smoke! Just nothing!
We did note the old adage. It didn't let the smoke out but kept it inside and the LCD window went all Smoky grey inside.
Never worked again and inside the meter was completely fried.
>>

Well I recall Fluke adverts justifying the expense of their DMM's (Which many now cost more than the cost of a basic Colour Digital Storage 'Scope!), with warnings about Plasma if surges occurred on the mains whilst measuring it.
But that was about protecting the operator, rather than their DMM surviving large over-voltages.
Although I think people put AVO 8's on current, across power supply outputs, and it survived as the needle triggered cut-out flew out!

Fluke also upped the spec. (and expense) of their 'Fluke fuses' from 50,000A to 100,000A surge resistance against rupturing.
As well as now having fuses with little margin above the full-range display (e.g. 11A? ones on a 10A range, when they used to have 15A? / 20A? ones).
Plus also not much margin on the main-ranges fuse (Was 1A? but now <=300mA?)
And so these can often get blown at > £10 each - more than the cost of many DMM's!

[ortek_service]

Originally Posted by paulsherwin

Apparently the DT830s use a chip derived from the old Intersil ICL7106 design, which has indeed been around for a long time: https://www.alldatasheet.com/html-pdf/72687/MAXIM/ICL7106/126/1/ICL7106.html

Yes, the 7106 was probably the first all-in-one 3.5digit LCD 200mV/2V FSD DVM IC - that you just need to add resistor dividers chains and switching, to make it into a full DMM (With 7107 being the LED version) -usually with 10M input resistance, if resistor values are selected accordingly.

And the first bench DMM I had was an Everyday Electronics 1980's project I built that used this (Although I discovered project details had lots of errors, so wonder how many had actually got it working)
With there also being later 7126 / 7136 ones (Probably mainly in smaller QFP packages than stand DIL40 one for 7106, if not obtained in die-form.

It's a well-proven IC, so quite-adequate for basic DMM's.
And it tends to be only more-expensive DMM Manufacturers go to the expense of producing their own custom ASOC's for their DMM's - presumably to add some extra features - But if spares of these are not obtainable, then DMM will be a write-off if this gets damaged.