Cheap multimeters
 

Hi,

I wasn't sure if this should go here or in the Modern Technology section...

On another forum I've got a thread running covering some cheap multimeters. Yes, I have several Flukes, but I've been investigating the other end of the market for a little while now, and thought that my latest purchases would be of interest...

For £15 delivered from the usual sources, the Aneng AN8008 is a new model that offers ridiculous functionality in a tiny, tiny package:

• True RMS
• 10,000-count
• Auto-ranging with manual over-ride
• Frequency and duty cycle (astonishingly, I've just measured 80MHz with it!)
• uA capability (10nA resolution)
• Capacitance (1pF resolution)
• Square wave out - 50Hz to 5kHz (no idea why, but it might appeal to some)

This one has only just arrived so I've not tested it rigorously yet, but I have been using the similar AN8002 for some months now. I really love the small form factor (yet large, clear display), and the build quality is very good for the price. The AN8002 is only (!) 6000-count, and lacks uA, but gives you temperature (thermocouple included) instead of square wave output. No manual ranging, sadly, which I guess would be a show-stopper for some. The AN8002 is about £12 delivered.

Yes, I know that you can get the DT830 for less than £3 delivered, but having seen inside those over the years, I'd always encourage folk to spend just a little bit more. Obviously, not everyone can afford (or justify) Fluke, but for £15, the functionality available from these Aneng meters is simply astonishing. For low-energy bench work, these are great meters. Don't use them inside your consumer units!

The OEM appears to be Zotek: http://szzotek.com/en/

I'll happily give more details if asked - this post is already longer than I planned. I'll end with some pictures. Note the Fluke 87V for scale ;)

Cheers,

Mark

Re: Cheap multimeters
 

Thats a pretty good feature set for the money. Can't complain at all. Its actually better than the uni-T UT61E for price/performance which I thought was virtually unbeatable. May grab one just to see at that price. Square wave is actually quite useful for signal injection if you use a tiny coupling capacitor and an AC voltage mode on the receiving end. I assume it has relatively low AC ranges, an annoyingly missing feature on DT830s?

I tend to do the same and have a collection of cheap meters. You can't have enough of them. Last scope I fixed I had 5 on the go. Certainly couldn't afford 5 Fluke 87V's as per a certain other forum's mantra. "What do you mean you don't have enough Flukes to cover your stairs?"

Re: Cheap multimeters
 

Mark.

One problem I have found with cheap DVMs is that they are blown up very easily by high transient voltages. I have a trail of dead ones behind me, while my Fluke meters continue to soldier on very happily. Specs and facilities are one thing, but at the end of the day I want something that is going to continue work year in year out.

The reason why transients are a big problem with vintage electronics is that large inductances and high (static) voltages are everywhere. Think of all the iron-cored inductors/transformers that can be found in virtually every older electronic product. And when you are dealing with valve circuits you will probably have at least 200V on the HT rail. When your DVM has a typical limit of 750V that leaves very little headroom.

Any switching of currents through those heavy iron-cored inductors will produce very high transient voltages with lots of energy. My AVOs (and Flukes) simply shrug it off so I don't need to worry about it. Only hard experience will tell whether these cheapie DVMs can do the same.


Richard

Re: Cheap multimeters
 

Interesting. Plus side:

1. The CE marks conform to the dimension requirements
2. The accessories include a pair of long-tip probes that seem to be marked 1000V CAT II, so suitable for insertion in a mains socket. In addition there seems to be a shrouded pair, which would be consistent with measurement on medium energy circuits - and the meter says 600V CAT III (so for instance a consumer unit).
3. Zotek's website has the CE certificates for Low Voltage Directive, EMC directive and FCC Variation.

Negative side

1. The whole transient thing. If there are not adequate insulation barriers in the lid, the terminals could arc across. Particularly for CAT III.
2. For CAT III the leads should be double insulated; from photos on the usual place they show the leads stripped and I suspect they are not.
3. The fuses at least seem to be ceramic bodied, so must have some level of high rupture capacity. But the distance between clips is small. In fairness fully specced HRC fuses fitted to Fluke are the same price as the entire £15 meter, and are physically huge.
4. What happens if you leave it set to ohms and put mains voltage up it? Flukes just go beep and shrug it off. Do flames come out of these meters? Well at least the manual says "don't do this", but people will. Like "pay attention when driving or you might die".

But for a £15 meter this seems to be of a decent standard, and a whole lot better than some of the cheapo horror stories out there.

Re: Cheap multimeters
 

Well, I've just bought one. For £15 what have you got to lose?

Craig

Re: Cheap multimeters
 

I've tried to blow up the CPC provided DT830 clone. The lowest priced one. They're quite robust. All I could get it to do is blow fuses (yes it has fuses that one). Stuck it across mains on 200 ohms range, with the provided probes, put it under a plastic tub and donned the safety goggles, powered it up and .... unexciting over range and new fuse required. 200mV DC range, 240v AC... over range no explosion. Quite impressed! I've connected them across a solenoid coil which peaks at a rather massive 2.8kv when the field collapses. Nope no problems! Don't use them for current on the unfused range though - that's just silly.

Now I'm not going to stick one near the bus bars in the DC in the office, but for average use, it'll cost you a new meter worst case.

The only bugbear of that particular clone is the 1M impedance on DC range which is a bit poo.

Re: Cheap multimeters
 

When digital meters came out I bought one and promptly blew it up trying to measure the resistance of the mains or something similar - and they weren't by any means cheap in those days, I eventually bit the bullet and bought a Fluke which is now so old that the display is falling apart but it still works!

I fairly recently bought a cheapie from ebay for about £15 and it's brilliant, even has a temperature probe with it and at that price it wouldn't be a disaster if it did blow up.

Peter

Re: Cheap multimeters
 

When it comes to safety, I did say "For low-energy bench work, these are great meters. Don't use them inside your consumer units!".

As someone who has more Flukes than I care to admit, I'm very aware of this issue. None of these cheap meters come with the sorts of safety features you'd expect in an expensive meter. The internal photo clearly shows a lack of MOVs, isolation slots, HRC fuses, etc.

Having said all that, this meter has been tested by Joe Smith - who is well known for testing multimeters to destruction - and it passes tests that the Fluke 87V did not! It survives mains voltages and 2500V transients applied to all functions (apart from current) with no problem. It took 3kV to damage it slightly, and ~6kV to kill the IC. And when it was hit with some high energy, the case remained intact - which is really what safety is about (personal protection, not necessarily surviving electrically undamaged). There's some impressive slow-motion explosions towards the end ;)

https://www.youtube.com/watch?v=HrcxnbkkhYg

Interestingly, the Fluke 101 survives all of Joe's tests, and can be found for about £40 from China. It doesn't have anything like the feature-set of the AN8008, but at that price, it's hard to justify not owning at least one guaranteed-safe meter.

But anyway, all this talk of safety is missing the point. What this meter lacks in robustness, it makes up for in functionality. Seriously, some of those specifications are in the territory of expensive bench multimeters. I forgot to mention that it has 1uV resolution in mV range. And I'll repeat that the frequency counter goes to at least 80MHz. That's mega-Hz! Joe read 200MHz with it (but didn't say how much signal level was required - my RF generator tops out at +17dBm, and 80MHz is the highest I could go with that).

It'll be interesting so see if it holds it calibration over time. Flukes generally do, but they use expensive thick-film divider networks rather than MELF resistors.

Oh, regarding the square wave output, I'm struggling to see why it's useful because it's fixed amplitude (3V pk-pk). While I haven't tested it yet, I suspect it's dependent on battery voltage. It's AC coupled, and Zout is around 2k. 3V is too high for most audio work, yet it's too low for most logic - I suppose it might just about be enough for 5V CMOS, but only just (and that's relying on the intrinsic body diodes to shift it up). Perhaps it'll appeal to the "makers" with their Arduinos, but I'm guessing most of us will have more appropriate generators...

Ultimately, for general bench work, this is so much better than the DT830.

Re: Cheap multimeters
 

Am I correct in thinking these meters come direct from China?

Re: Cheap multimeters
 

The square wave could possibly be used for adjustment of the low frequency compensation on a 10X oscilloscope probe. Most oscilloscopes have a square wave output for this but I recently acquired a Scopex 4D 10A that hasn't.

I do not have this multimeter so cannot try it to see if the output is sufficiently square.

David

Re: Cheap multimeters
 

Yes, that's a possible application. It is a good quality square wave, with no ringing or overshoot and fairly quick rise time.

And yes, they come from China via the usual sources. It's OK to mention eBay in this context - just search - also Aliexpress and Banggood, and no-doubt many others...

https://www.banggood.com/ANENG-AN800...p-1157985.html

https://www.aliexpress.com/store/pro...813459910.html

Cheaper on eBay though. I ordered mine on July 1st, and it arrived on the 11th. I've never had a problem with cheap Chinese electronics ordered that way :thumbsup:

Re: Cheap multimeters
 

Always let the buyer beware with direct imports. I will never do it with test equipment like this.

You can get extremely cheap, but properly verified, tested and certified meters from suppliers like Rapid, Maplin, CPC etc. You know the CE mark is genuine and the double insulated classifications and safety approvals are too; the distributors have the weight of EU and UK law, responsibility & traceability over them.

Chinese direct shippers have none of that.

Re: Cheap multimeters
 

For work, that's certainly true. A few months back I purchased a dozen Fluke 115s to replace our ageing Fluke 75s. I've also bought a few of the RS Pro RS-14 meter.

However, we're talking about hobbyists here. I'm trying to reach out to the folk on this forum who think nothing about using sub-£3 DT830s.

This meter is not a Fluke, and nor does it claim to be - although if you watch Joe Smith's video, you'll see that it does pass tests that a Fluke 87V fails.

Interestingly, if you go to the OEM's website, you'll find some certification for the meters - for example, the AN8002 is here: http://szzotek.com/en/col.jsp?id=133 - there isn't anything for the AN8008, but I presume that's because it's so very new. The CAT ratings haven't been independently verified - and they are almost certainly "optimistic" - but that's true of many, many multimeters, including ones supplied by big UK suppliers. The CAT scheme is self-declaring and companies like Fluke voluntarily submit theirs for independent testing (mostly for marketing reasons)

Re: Cheap multimeters
 

Moving up a notch, as used by "BIG CLIVE" the AMECAL ST-9905.

Huge display, great for us oldtimers.

Fully manual.

http://www.ebay.co.uk/itm/AMECaL-ST-...sAAOSwCGVX9KmZ

Re: Cheap multimeters
 

This is loosely true. If you look at the UT61E from rapid it's got the same guts as the UT61E from a Chinese drop shipper. Same MOV arrangement, fuses etc. The difference is £100 vs £40.

Not the best meter for the comparison however.

Also to add, and I've said this elsewhere, probe accidents are far more common than meter explosions. Wear safety glasses!

Re: Cheap multimeters
 

Wow - that's quite a price for a basic 2000-count manual-ranging meter. Not true-RMS,and the accuracy specifications are no better than the Aneng meters. I've seen that meter often enough in his videos, but assumed it was a third or a quarter of that price. Has anyone done a tear-down?

Must admit that I prefer auto-ranging meters, providing they have a manual mode as well. But obviously that's a personal preference.

Re: Cheap multimeters
 

I believe there are 2 versions of this meter, with different amounts of protection components fitted. IIRC, this was a result of getting approval to sell it Germany?

Re: Cheap multimeters
 

I have a number of under £3 digital meters I keep in my vintage vehicles. Absolutely great and they get you and others out of trouble but of course they would not be used for any serious work. Calibration is excellent compared with my expensive kit for basic voltage and resistance readings.

The AN8008 appears to be fantastic value and trustworthy. £15! I paid a great deal of money for my AVO 8 in 1971 but it certainly earned it's keep. John.

Re: Cheap multimeters
 

Possibly. It's likely by the time I got hold of the two that they had consolidated the lines into one. I still rather like the UT61E - it can be accidentally pulled off the bench three times a day and survive it :)

Re: Cheap multimeters
 

I still haven't got around to buying a UT61E - partly because of that issue. One day...

Meanwhile, I've done a load more testing on the Aneng meters. I've verified that they do indeed read true RMS, measured the current consumption and cut-off points, and proved that the square wave amplitude is equal to the battery voltage.

Because I'm posting on 3 forums about this meter, I've decided it's easier to continue putting the bulk of the details in one. It's confusing trying to remember what I've said where! So here's the thread on Golborne (I trust it's OK to link to it?): http://golbornevintageradio.co.uk/fo...d.php?tid=5501

That thread contains reviews of a few other cheap meters, so hopefully it's of interest. For those who aren't members, you'll be able to read the thread, but you won't be able to enlarge the images - let me know if you'd like me to add them here instead (and I plan to put the material on my website soon). Of course, I'll be continuing to reply here.

Cheers,

Mark