Author Topic: Mini-DMM recommendations?  (Read 6327 times)

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Offline Winston

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Mini-DMM recommendations?
« on: April 06, 2015, 10:06:22 pm »
I'm looking for a fairly rugged, inexpensive mini-DMM for inclusion in R/C aircraft and rocketry hobby field boxes. Only low voltages and continuity would be measured and extreme accuracy is not needed. Any recommendations? Various really cheap (apparently too cheap) mini-DMMs I've tried have all eventually died even though little used, some while just sitting in the field box, like this one:

http://www.harborfreight.com/7-function-multimeter-98025.html
 

Offline xrunner

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Re: Mini-DMM recommendations?
« Reply #1 on: April 06, 2015, 10:13:32 pm »
I am a Test Equipment Addict (TEA) - by virtue of this forum signature, I have now faced my addiction
 

Offline rollatorwieltje

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Re: Mini-DMM recommendations?
« Reply #2 on: April 06, 2015, 10:16:09 pm »
Fluke 101 if you don't need current capability. For power measurements I use one of those power analyzers like this.
 

Offline dadler

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Re: Mini-DMM recommendations?
« Reply #3 on: April 07, 2015, 12:04:11 am »
Recommend Brymen BM20 series, the specs vary a bit. I have the BM27s and it's a great pocket meter.

http://www.brymen.com.tw/product-html/cata20/BM20_Catalog.pdf
 

Online Ian.M

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Re: Mini-DMM recommendations?
« Reply #4 on: April 07, 2015, 01:00:04 am »
+1 for the Bryman.  I've been using a couple of the Maplin 'Precision Gold' badged versions of the BM22 for about 8 years.  One lives in the boat's engine toobox, not exactly the best storage environment and the other gets toted around with me in my pocket toolkit.  Both have been trouble free apart from some high resistance tarnish that polished off the probes of the boat one quite easily.

If you are making up adapters for its probes to various servo connectors etc. the female contacts from 5 1/4" disk drive power connectors fit the probes nicely.  Add a bit of heatshrink and you have a neat little adapter.  I also keep some croc clips made up with the same female contact inside their insulating sleeve.

The BM22 frequency range will respond to unipolar logic level pulse trains so you can use it to check for the presence of servo and ESC signals, even though a standard Futaba servo signal is outside the published specs for frequency range duty cycle.  I would suspect the others are also suitable.
« Last Edit: April 07, 2015, 01:02:05 am by Ian.M »
 

Offline apelly

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Re: Mini-DMM recommendations?
« Reply #5 on: April 07, 2015, 01:23:45 am »
Yes, Bryman have some good options. Here's a recent thread that might be helpful:

https://www.eevblog.com/forum/testgear/pocket-multimeter-recommendations/

I went with the BM27. Got 2 actually.
I'd rather a Google clue, link, or some theory than "do this" (generally)
 

Offline smjcuk

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Re: Mini-DMM recommendations?
« Reply #6 on: April 07, 2015, 07:27:52 am »
Avoid the bottom end Uni-T ones. They are frustratingly slow and whinge at you if you leave them on which gets really annoying if you're doing lots of measurements.
 

Offline Winston

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Re: Mini-DMM recommendations?
« Reply #7 on: April 07, 2015, 03:00:38 pm »
Yes, Bryman have some good options. Here's a recent thread that might be helpful:

https://www.eevblog.com/forum/testgear/pocket-multimeter-recommendations/

I went with the BM27. Got 2 actually.
Thanks for that lead. I was searching on the wrong keywords to find any already existing threads on this topic.
 

Offline Winston

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Re: Mini-DMM recommendations?
« Reply #8 on: April 07, 2015, 03:06:11 pm »
Avoid the bottom end Uni-T ones. They are frustratingly slow and whinge at you if you leave them on which gets really annoying if you're doing lots of measurements.
I was considering the UT33D which I can get for $13 from a US source and it's fairly well reviewed:

http://www.amazon.com/dp/B00KHP6EIK/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=B4MQ1L5GPTB2&coliid=I2MYBUJD4VKMJJ

One reviewer did mention the power warning alarm, but since in the field I'd only be using this for continuity checks and checks for the presence or absence of low voltages, the warning may be useful in preventing me from putting the DMM back in the field box with the DMM still turned on. How long must the DMM be on before the alarm sounds?

EDIT: just found this thread on the UT33D:

https://www.eevblog.com/forum/testgear/uni-t-ut33d-very-low-cost-multimeter-teardown-and-review/
« Last Edit: April 07, 2015, 03:08:31 pm by Winston »
 

Offline smjcuk

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Re: Mini-DMM recommendations?
« Reply #9 on: April 07, 2015, 10:26:32 pm »
Seen those. I've actually got 2x UT33As for secondary measurements. Takes about 5 minutes before it starts beeping at you. I was thinking about clipping the beeper off inside them as it's just annoying.

They're probably fine for what you need though. They have probe tip covers now and seem to be relatively well made.

My go to meter is still an ancient Fluke 77 however. Don't care if it's large :)
 

Offline Harrkev

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Re: Mini-DMM recommendations?
« Reply #10 on: April 07, 2015, 10:42:12 pm »
When Radio Shack was going under, I got one of these:

http://www.radioshack.com/22-range-pocket-digital-multimeter/2200820.html

Comes with it's own case which seems rather rugged, and it does the basic.  Being a decent brand (well, depends upon your definition of "decent") you can be pretty sure that they are not lying about the cat rating.  I like mine.  It even does current!

Of course, most Radio Shacks are closed, so it may be hard to find.  I got mine for 1/2 off which is a pretty good deal.  At full price it is less of an attractive item.

The other meters mentioned here seem pretty nice for the money, but are physically larger than the Radio Shack one.
 

Offline Muxr

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Re: Mini-DMM recommendations?
« Reply #11 on: May 27, 2015, 03:40:00 pm »
A multimeter will last you a very long time, decades. It really makes little sense to skimp on it. I would stay away from the super cheap UNI-T meters (they have a few ok models, but the low end stuff is shoddy).

It's a measuring device, you want the confidence that the thing will A.) give you a good reading B.) is safe to use, should you use it to measure currents or higher voltage.

This is why I would at least get a Fluke 101, 107 or 15B. Or one of the other decent brands like Brymen.

There is a world of difference between a $13 meter and a $70 meter. And trust me $70 on a decent meter is money well spent. Meters get outdated slowly, 30 year old Flukes are still used for instance, and they are built like tanks so chances are it will never break (you might replace a fuse here or there but that's about it). So it makes no sense to skimp on it.
« Last Edit: May 27, 2015, 03:41:40 pm by Muxr »
 

Offline smjcuk

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Re: Mini-DMM recommendations?
« Reply #12 on: May 27, 2015, 05:02:33 pm »
I've got a ruggedised Fluke 77 already.

It's no good for this use case: small enough to slide into my bag with a handful of components so I can fiddle with things when I'm on holiday. I'm talking max 200mA, 9v alkaline cells here and the meter is fused. What I need is a basic frequency counter and a DMM for this case. The Fluke doesn't hit the mark.
 

Offline Muxr

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Re: Mini-DMM recommendations?
« Reply #13 on: May 27, 2015, 05:07:40 pm »
I've got a ruggedised Fluke 77 already.

It's no good for this use case: small enough to slide into my bag with a handful of components so I can fiddle with things when I'm on holiday. I'm talking max 200mA, 9v alkaline cells here and the meter is fused. What I need is a basic frequency counter and a DMM for this case. The Fluke doesn't hit the mark.
I am actually also looking into a small meter (for travel), and so far 107 seems to be the one I will get (I like my meters with a backlight). It does have frequency measurement. The only thing it's missing is temperature.
« Last Edit: May 27, 2015, 05:09:19 pm by Muxr »
 

Offline smjcuk

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Re: Mini-DMM recommendations?
« Reply #14 on: May 27, 2015, 05:56:09 pm »
Lick finger, touch item, does it sizzle? Yep. >100oC :)

This mentality has lead to my party trick: change the tip on my soldering iron with my bare fingers without waiting for it to cool.
 

Online Fungus

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Re: Mini-DMM recommendations?
« Reply #15 on: May 27, 2015, 06:26:43 pm »
It's no good for this use case: small enough to slide into my bag with a handful of components so I can fiddle with things when I'm on holiday. I'm talking max 200mA, 9v alkaline cells here and the meter is fused. What I need is a basic frequency counter and a DMM for this case. The Fluke doesn't hit the mark.
I just got a UT120C and I'm happy with it:

https://www.eevblog.com/forum/testgear/uni-t-ut120c-review-and-tear-down/

400mA current readings with a self-recovering polyfuse for overloads (which is fine by me for testing batteries, 5V rails, etc.). It even has a PTC. :-)

Good size, nice carry case, plenty of features, under $20 on eBay.

 

Offline paulie

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Re: Mini-DMM recommendations?
« Reply #16 on: May 27, 2015, 06:33:56 pm »
I am actually also looking into a small meter (for travel), and so far 107 seems to be the one I will get (I like my meters with a backlight). It does have frequency measurement.

100khz is barely frequency measurement. Maybe OK for typical audiophool. 10mhz built into the cheapies considerably more useful. For a real frequency counter hard to beat one of the 2.4ghz $10 Ebay deals.

WARNING: For those with fear of solder it is necessary to connect a cable up to it:



ps. The black box is not part of the counter but is actually DUT.
 

Offline smjcuk

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Re: Mini-DMM recommendations?
« Reply #17 on: May 27, 2015, 06:37:12 pm »
I made a รท10/100 prescaler already
 

Offline paulie

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Re: Mini-DMM recommendations?
« Reply #18 on: May 27, 2015, 06:45:48 pm »
Oh yeah... turns cheap mhz multi-meter counter into ghz like magic. I use MB506, hard to beat for less than a buck. Specially considering  you'd have to pay a grand or so for that capability few years ago. The front end is important too so I copied the 998 dual gate FET circuit from the Ebay counter. Do you have a link to yours?
 

Offline smjcuk

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Re: Mini-DMM recommendations?
« Reply #19 on: May 27, 2015, 06:58:03 pm »
I haven't drawn it up yet. Its two halves of a 74hc390 basically each /10 with a bc337 common collector arrangement up front. It's mostly reliable so far. I'll post it when I'm happy with the design.
 


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