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Old 1st Jan 2019, 12:37 am   #1
1100 man
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Default New multimeter required- specific criteria

My Maplin Gold meter that I bought some 30 years ago has now got to the point where I can't trust it's readings. It does increasingly odd things so I've been looking round for a suitable replacement.
However, I have three specific requirements which seem to be rather hard to satisfy.

1) MANUAL ranging. I've never liked auto ranging meters: much prefer manual.
2) NO auto power off. This drives me insane when I go to use it 10 mins later and it's turned itself off!
3) INSTANTANEOUS continuity bleeper. I've used meters before with a half second delay when you touch the prods which is no use to anyone.

It doesn't need to have fancy features like component testers, capacitance etc. It's main use is for TV work, so voltages up to 1000V & resistance to 20 meg will be fine. I guess it would need to be cat iii 1000V.

Budget would ideally be about £50.

So far, I've not found anything suitable- everything seems to have auto power off.

Does anyone know of a meter that doesn't have auto off? Also, you can't tell from looking at specs if the continuity bleeper is instant or has a delay.

I know lots of folk recommend Fluke and I would consider a second hand one (obviously I would have to up the budget) if it would meet all three criteria.

If I have to, I will compromise on the auto ranging but not the other two criteria!

Any help and personal experience gratefully received!

All the best
Nick
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Old 1st Jan 2019, 1:14 am   #2
Boater Sam
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Default Re: New multimeter required- specific criteria

Avo model 8 could be the thing then if it had a buzzer?
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Old 1st Jan 2019, 1:35 am   #3
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Default Re: New multimeter required- specific criteria

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Originally Posted by Boater Sam View Post
Avo model 8 could be the thing then if it had a buzzer?
I can offer no excuse for not using the Avo 8 that also sits on the bench! For some reason though, I always use it to measure current, particularly when reforming electrolytics.

I certainly can't condemn it for having auto off or auto ranging! I also never got the hang of testing transistors with a DVM- the leads are the wrong way round!!

Cheers
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Old 1st Jan 2019, 6:36 am   #4
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Default Re: New multimeter required- specific criteria

Firstly a general point. The continuity beeper is turned on when the voltage between the probles is less than a certain value in diode test (or resistance, sometimes) mode. Cheaper meters detect this using an analogue comparator circuit which is fast. More expensive meters, including the Flukes I've tried use the ADC and compare the result digitally which introduces a delay. It's one reason I won't use a Fluke meter!.

Secondly, on manual ranging meters you might want to choose the cheapest model in the range, with the fewest function. The reason is that often the same case/range switch knob is used in all models in the range so the total number of ranges is the same in all models. In turn, if you have more functions (frequency, temperature,...) you lose some useful ranges (perhaps a couple of the current ranges are removed). I'd rather have a few functions with the ranges I need and have a separate thermometer, frequency counter, etc.

I have one of those Uni-T meters which I got from Maplin some years ago. I am sure it is not safe for working inside a consumer unit, but it probably is OK on the bench where fault currents are more limited. It meets the 'manual ranging' and 'fast beeper' requirements, but originally it was auto-power-off. That drove mad too (in fact all 3 of your requirements are high on my list of requirements too) so I opened it up, found the power switching transistor and soldered a link between collector and emitter. The meter seems unaffected by this and no longer turns itself off. I am not sure why it was auto-power-off in the first place. The power consumption is pretty low, I've left it turned on overnight by accident a few times and the battery was still OK in the morning. I'll post the exact model number later if you are interested.
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Old 1st Jan 2019, 11:04 am   #5
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Default Re: New multimeter required- specific criteria

Buy an old fluke 8024B series handheld if you can get one. Usually around £20 on eBay etc. 1kv, continuity that doesn’t suck, shrouded leads, HRC protected front end, doesn’t auto power off, manual ranging, lasts months on a battery, constant input impedance making it easier to use for HV probes etc.

Later flukes have crappy continuity up until the 87 series which are a lot more expensive than £50.

I haven’t found a better new meter than the 87V if I’m honest and I’ve had quite a few now.
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Old 1st Jan 2019, 11:22 am   #6
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Default Re: New multimeter required- specific criteria

I guess trying to find another Maplin Gold identical to your meter without faults, could be a challenge.

Would you consider a bench multimeter, rather than hand-held?

I have a Fluke 45, CatIII, up to 1kV, mains powered so no auto power-off, can select 'response' level slow, medium, fast and has a dual read-out.

Their may be some of these or other brands of this design online within your budget, failing this, Mr Bungles onto something

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Old 1st Jan 2019, 11:27 am   #7
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Default Re: New multimeter required- specific criteria

Among the meters from China, I like the ones from UNI-T, which cover a price range from about £15 to 350. The one I have (which is the day to day workhorse, while the Avo8 sits in a drawer waiting for the difficult jobs) was just £15 and is only 300V CatII, but is manual ranging and no -auto off. No doubt there are better meters for high voltage further up the price range.

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Old 1st Jan 2019, 11:38 am   #8
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Default Re: New multimeter required- specific criteria

UNIT UT-105
quite old ,maybe brand new are worst or have different features

fast and LOUD continuity test
manual ranging
lack of auto power-off
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Old 1st Jan 2019, 6:01 pm   #9
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Default Re: New multimeter required- specific criteria

Auto power-off, a terminal nuisance (pun intended)
Is it for people who forget to switch the engine off when they get home from work..?
Every DMM i look at so far is lacking in one of the OP's criteria. EEVblog might be a useful place to look.
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Old 1st Jan 2019, 6:45 pm   #10
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Default Re: New multimeter required- specific criteria

Manual ranging, true RMS, 6000-count: https://www.markhennessy.co.uk/budge...ide_adm08a.htm

You can disable auto power off by holding down a button while powering up.

The UniT UT61E stays on - no power-down mode offered. But it's auto-ranging. Manual override is available: https://www.markhennessy.co.uk/budge...unit_ut61e.htm

Both have reasonable continuity beepers, and should be available for your budget.

I quite like the mini-bench Fluke meters - especially the 8050A - but watch out for bad LCD screens at this age. If you pick up a version that has batteries, then the batteries need to be in good condition for the meter to work on mains. The mains-only models are simpler in that respect.

The 8060 is a great meter - it shares many features with the 8050, but is in the hand-held case with pushbuttons down the side. It was designed for wide AC bandwidth, so is great for audio work, which is why I like it. Hard to find a good one for £50 though.

Not sure about the comment about later Flukes having poor continuity speed. Even the humble 101 is pretty good. I have a 179 that's at least as good as an 87V. I've never tried the original 87, which I think is the meter Tony might be basing his comments on. Plenty of other Flukes from that era (e.g., 25, 75) are absolutely fine, so this is a generalisation too far IMHO. But finding a good Fluke for £50 is tough - not impossible though. Often, ex-forces 25s turn up in batches for less than £40. They're big and tough, and have usually lived in a chunky case all their lives. A bit basic, but they do what they do well.

Brymen make some good meters if you can stretch your budget: https://www.amazon.co.uk/BM235-Digit...po_vtph_tr_t_2 - this one is probably the safest meter at this price point. You can manually range it, and while I'm not sure if you can disable auto power off, it does have something called "intelligent APO", which only allows power-down after 30 minutes of genuine non-use.

Lots of choice!

Last edited by mhennessy; 1st Jan 2019 at 6:51 pm.
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Old 1st Jan 2019, 7:24 pm   #11
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Default Re: New multimeter required- specific criteria

Just a point on the fluke 7x/2x meters: the continuity is awful I find.
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Old 1st Jan 2019, 8:33 pm   #12
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Default Re: New multimeter required- specific criteria

Nick, while I sympathise with your requirements, they strike me as sometimes in conflict with each other. Starting with auto power-down, why wouldn't anyone want it? It so frustrates me to go looking for the DMM I was using last week, only to find it still on with the display faded almost to nothing; but what I do want is a separate on/off button so you don't have to sweep a wiping-contact switch back and forth to reset it.

Much the same goes for the continuity tester: I would not be wanting to switch on and twist a knob to test for continuity, so I use an old GPO unit (165A) which is truly instantaneous. It runs on a PP3 which is a little high for prodding around among the more delicate semicons, but one could make one's own to be instantaneous with low emf and pre-defines conductance limit.

I love Mark's Budget Multimeters pages, a bit of browsing there should find a model for anyone's needs. That reminds me, another thing I want for the ideal portable DMM is operation from 2 × AA cells. I have a selection of Micronta meters which do that, from the days when Radioshack was in its prime. I wonder how Mark would rate some of those!
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Old 1st Jan 2019, 9:34 pm   #13
mhennessy
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Default Re: New multimeter required- specific criteria

Quote:
Originally Posted by MrBungle View Post
Just a point on the fluke 7x/2x meters: the continuity is awful I find.
Have you tested it?

Function generator -> MOS-FET -> Meter

About 60ms for a Fluke 25. Not the fastest, but hardly "awful".

My 79 (Series 2) is about 1.3ms. So not all the 7x series is awful by any means.

About 120ms for the Uni-T 61E. This is starting to get noticeable, but hardly a show-stopper, especially as you will have already slowed down quite a bit to use this particular meter

About 12ms for the BSIDE ADM08A. Pretty good for a cheap meter. The same chipset is in many other cheap meters, of course - the ones I have here are all very similar.

About 20ms for the Brymen DM235

The super-fast ones are sub-1ms: the Fluke 87V (850us), 189 and 287 (330us), 179 (150us). The 8021B and 8060A are both around 150ns, for what that's worth.

However, in day-to-day usage, these figures are all a bit academic. It takes half a second to be sure you've made a decent contact with whatever you're trying to measure - things oxidise. Whizzing a meter probe over the back of an edge connector and trusting it all to the meter is asking for trouble. This business of furiously banging the meter probes together in a meter review might look great on camera, but I really wish Dave Jones hadn't started everyone doing this - there are far more important metrics out there. All these meters are lot faster than the AVO. Just for a laugh I chucked a couple of batteries into my old Altai HM-102BZ - the mechanical buzzer in that needed about 90ms to start making noise, so better than the Uni-T

None of these are in the 300ms region (~3 readings per second), so are unlikely to be using the main ADC for this (if that was ever actually done?).
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Old 1st Jan 2019, 10:07 pm   #14
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Default Re: New multimeter required- specific criteria

My old Fluke (1980 something, a 8022B I think) had a dedicated continuity beeper based on a CMOS logic chip, it would beep in microseconds for about a hundred ms (even when the contact was a few us) and "unbeep" for another hundred ms when a quick (again us) open happened. The very best continuity beeper I have ever used, great for intermittent cables. You could drag down a multi pin connector in less than a second to identify what went where.
 
Old 1st Jan 2019, 10:28 pm   #15
1100 man
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Default Re: New multimeter required- specific criteria

Wow, that's some response- Many thanks to everyone for writing such detailed replies

Mark Hennessey. Lots of reading to do on your site- thanks for the link and for putting actual numbers to the continuity bleeper times! That's really helpful.

As regards auto power off, my clamp meter (used for current measurement) which I have been using, turns off after 10 mins- even if you are in the middle of taking a reading! I could live with 30min shutdown after no activity though.

I did buy an identical Maplin Gold meter at Harpenden for a couple of quid, but it's even more faulty than mine! I did swap the big socketed chip over (size of a Z80 CPU), but that didn't alter the fault. I can't find the correct circuit diagram for it, so gave up trying to fault find it.

Right, time to do a bit more detailed reading.

Many thanks
Nick
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Old 2nd Jan 2019, 5:28 pm   #16
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Default Re: New multimeter required- specific criteria

Ex-MoD Fluke 25 complete with 'turtle-shell' case. I bought two, £28 and £32 respectively off eBay several years ago. This instrument will meet your requirements.
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Old 2nd Jan 2019, 6:07 pm   #17
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Default Re: New multimeter required- specific criteria

Just a point on the continuity, the faster the initial response the better because you can pick up intermittent connections easily then. Also some of them with pulse stretching tend to mask intermittent connections. 87V is about right across the board.

Fluke 7x and 25 (as well as the UT61E) derive continuity from the first approximation of the ADC AFAIK hence slow and even worse, inconsistent between readings.

Worst meter ever is the TTi 1604. A whole 500ms if you’re lucky.
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Old 2nd Jan 2019, 6:35 pm   #18
1100 man
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Default Re: New multimeter required- specific criteria

I've been looking at Fluke meters but there seems to be a bewildering array. I've been trying to make sense of what series is what but haven't made much headway!

There is quite a selection on Ebay for less than £100 both new & second hand.

Mark. Your 'budget multimeters' section has been most useful- I don't suppose you have done similar reviews in the £50 to £150 price bracket?

Many thanks
Nick
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Old 2nd Jan 2019, 11:27 pm   #19
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Default Re: New multimeter required- specific criteria

Quote:
Originally Posted by MrBungle View Post
Fluke 7x and 25 (as well as the UT61E) derive continuity from the first approximation of the ADC AFAIK hence slow and even worse, inconsistent between readings.
I didn't know that; thanks. Just been and had a play with one of my 25s and after a couple of goes, there's an extremely short discernible delay. But I've never had any continuity checking probs with it. No worse than the tried-and-trusted delay on the wooden bell-box we used to use years ago!

I have noticed distinct delays on other meters, mind, including Fluke ones.

Well... Two out of three ain't bad.
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Old 2nd Jan 2019, 11:40 pm   #20
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Default Re: New multimeter required- specific criteria

Quote:
Originally Posted by MrBungle View Post
Fluke 7x and 25 (as well as the UT61E) derive continuity from the first approximation of the ADC AFAIK hence slow and even worse, inconsistent between readings.
Only, most multimeters, including those, use dual-slope converters, not successive approximation converters. A complete cycle (auto-zero, charge, discharge, etc) has to take place before you get any sort of reading, and typically, that reading is the full and final reading.

So whatever they're doing, it's not as simple as that.

There are a few breadcrumbs in the Fluke service manual, but real data is scant for obvious reasons, and I can't make the numbers work based on what they've given away. Likewise, there is some information in the datasheet for the ES51922 used by Uni-T, but again, I can't square the numbers - there's obviously more to this that they're letting on. However, successive approximation it ain't.
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