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Recommendations for a DMM

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mzincali

Mon Jan 02 2012, 08:20PM

Registered Member #4127 Joined: Fri Oct 07 2011, 05:40PM
Location:
Posts: 22

Happy New Year!

I am looking for a DMM in the $200 price range. I would like it to measure:

resistance 0-20MÎ©

voltage 100mV-1000V

amperage 100mA-10A

capacitance 1nF-10uF

frequency 1Hz-100kHz

Measuring inductance and testing transistors would be nice to have too. Being compatible with high voltage probes is a must.

The units I have looked at are:

Craftsman 74756

Craftsman 82003

Fluke 117

Fluke 179

Fluke 87-5

Protek 6500

Amprobe 37xr-a

Extech 530

Extech 430

Extech 470

I definitely would prefer auto ranging, unless I am giving up something else that is important.

Please tell me if I should consider other brands/models, how you like your DMM, and whether you wish you had another model instead.

Thank you!

GluD

Mon Jan 02 2012, 10:00PM

Registered Member #1221 Joined: Wed Jan 09 2008, 06:17PM
Location: Odense, Denmark
Posts: 196

I have a fluke 117 myself and am very happy with it, but I dont think it can measure all the things you want to measure. For example the max voltage is only 600 volts which I think is common for many DMM's.

Also auto ranging and high voltage probes dont work together as far as I know.

mzincali

Mon Jan 02 2012, 11:12PM

Registered Member #4127 Joined: Fri Oct 07 2011, 05:40PM
Location:
Posts: 22

GluD wrote ...

I have a fluke 117 myself and am very happy with it, but I dont think it can measure all the things you want to measure. For example the max voltage is only 600 volts which I think is common for many DMM's.

Also auto ranging and high voltage probes dont work together as far as I know.

Thank you for the info. I think I can live with 600V too, but I was hoping to push it as far as the limit on one of the clamp meters I was considering.

If probes and auto-ranging don't work together, then I have to rethink this. Maybe I need to find myself a separate high-voltage VM (and ammeter?) instead to augment a nice auto-ranging.

Frequency is important, since some of my projects involve flybacks. How is the 117 at frequency measurement? Can it read frequency on the current line too?

radiotech

Tue Jan 03 2012, 12:40AM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

The frequency parameter is going to be a problem at the low end. I don't know
if there are meters that can utilize their count accuracy to display time period instead
of frequency. 50 Hz would read 20.00 mSec on a 3- 3/4 digit 4000 count meter.

Sulaiman

Tue Jan 03 2012, 09:52AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

At work I use Fluke dmms, very good;
I like the twin line display, e.g. Vac and Vdc simultaneously
My workmate has one with a built in 'Megger' function which I find useful.

At home I use cheap dmms because playing with eht,
accidental killing of a dmm is easy
and the cheap ones are accurate enough.
(I can't remember when I last needed better than 1% accuracy)
P.S. comparing cheap dmms with traceable calibrated dmms at work, accuracy has been better than specified.

I'd be more inclined to get
one very cheap dmm,
one cheap dmm with many ranges and a P.C./logging interface
and one of those $100 portable oscilloscopes
(a picture is worth the loss of accuracy/resolution)
(a 200MHz bandwidth 'scope is better but even 200kHz is useful)
and you'll have left over some money for beer!
(or spare leads/probes/fuses)

P.S. The common dc/mains frequency high voltage probes have separate + and - leads/plugs so work with almost any dmm.
P.P.S. there seem to be many different 'standards' for 4mm shrouded connectors, not all interchangeable.

Steve Conner

Tue Jan 03 2012, 11:32AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

The issue with autoranging and high voltage probes is that the input resistance of the meter often changes depending on the range, but the probe assumes a fixed value. This can cause the autoranging to hunt endlessly.

I've never found it an issue, as every autoranging meter I've used has had an option for manual ranging.

radiotech

Tue Jan 03 2012, 07:32PM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

Another function that seems to be appearing on cheap meters is duty cycle.
This can be useful to set the symmetry of pulse trains, or ever mechanical
devices.

I recent bought a set of twelve auto/manual ranging DMMs for less than
$20.CAN each. They are for classroom use. They are deeply discounted from $80.
from time to time at our local big box hardware.

I opened one and counted about nine trim potentiometers. They are 4000
count meters. So they can be calibrated for special purposes.

One has already been 'blown up'. However after the fuse was replaced it seemed to
work ok.

For $10. more you can buy the temperature probe. It is a 2wire thermocouple
with a plug that fits meter jacks.

The specs have an error. The K should be M in the input Z spec.

rp181

Wed Jan 04 2012, 12:00AM

Registered Member #1062 Joined: Tue Oct 16 2007, 02:01AM
Location:
Posts: 1529

I use this:

I like it better than the flukes I have used (though more from a design standpoint). Judging from the picture, I think the fluke I use is a 117. The capacitance measurement isn't the best as it is meant for leaded components (you can't use the probes).
Its very good on the batteries too, Haven't replaced them yet for two years.

mzincali

Wed Jan 04 2012, 02:23AM

Registered Member #4127 Joined: Fri Oct 07 2011, 05:40PM
Location:
Posts: 22

Are there many DMMs that can do volt and current at the same time? i.e. there is a pair of leads for input and a pair for output?

Also, are there DMMs that can tell you frequency and duty cycle at the same time as doing ~V or ~A?

rp181

Wed Jan 04 2012, 04:52AM

Registered Member #1062 Joined: Tue Oct 16 2007, 02:01AM
Location:
Posts: 1529

I haven't seen any, best bet is to get a clamp meter for current.

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