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Author Topic: DMM suggestions?  (Read 7448 times)

John Roberts {JR}

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Re: DMM suggestions?
« Reply #20 on: January 02, 2014, 09:42:02 am »

Years ago I figured out the hard way that there are two problems with cheep tools.  First, you own a cheep tool that doesn't work as well as a quality tool.  Second you own that tool so it is hard to justify replacing it with a good one.

I now buy quality even if I have to buy old used quality rather then new cheep.  There are working Fluke DMM on Ebay starting at $30
I probably have a somewhat different perspective on this after spending 15 years designing "value" sound gear. There is often confusion between low quality and a reduced feature set. Being intimately familiar with what is going on under the hood, there is often a significant price premium in name brands that in my judgement is more about the name and not justified by the internal content. 

There is nothing wrong with buying premium gear if it makes you feel good. You can find quality gear across the full range of prices and feature sets. Of course these days you can also find tools and gear that are too cheap to work... This is true of the components that go inside gear too. I rejected as many new component vendors as I approved while working at Peavey.

YMMV

JR
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Mike Sokol

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Re: DMM suggestions?
« Reply #21 on: January 02, 2014, 11:51:00 am »

No covers over the slots?  Our sockets have covers over live and neutral which are moved out of the way by the insertion of earth pin.

Covers on the slots??? You must be kidding. Here in AMERICA we give everyone the same right to easy electrocution.

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Jonathan Johnson

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Re: DMM suggestions?
« Reply #22 on: January 02, 2014, 12:39:52 pm »

Covers on the slots??? You must be kidding. Here in AMERICA we give everyone the same right to easy electrocution.

Here in North America we now have available "tamper-resistant" receptacles, which have shutters over the current-carrying (120V hot and 0V neutral) slots. These shutters are designed to block entry into a single slot; both prongs must enter simultaneously in order for the shutters to open.

Because NA standards allow for ungrounded, two-wire devices, it's not feasible to create a receptacle which requires insertion of the ground pin to release the shutters.

Apparently, the 2008 NEC requires tamper-resistant receptacles in all new residential housing. I wouldn't be surprised if it soon expanded to include commercial applications. I've actually started replacing the receptacles in my church with TR, as we've got a lot of little kids running around there.




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Mark Cadwallader

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Re: DMM suggestions?
« Reply #23 on: January 02, 2014, 10:53:44 pm »

Thanks to all for the suggestions and thoughts. My cheap multimeters are the $25 ones from Sears or RatShack; more suited to motorcycle and automotive use (which was their original purpose).

I think that I will be looking for a Fluke 117. As noted, the 177 looks great, but seemed to me to be rather pricey. I'm glad to hear that I don't need to spend that much for a reasonable quality tool.  The dedicated power meters look nice, but I think that a DMM is a better place to build from. Mark C.
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Guy Holt

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Re: DMM suggestions?
« Reply #24 on: May 27, 2015, 11:24:37 am »

Always use common sense with any meter.. if the reading doesn't make sense, maybe it's wrong... triangulate and understand that the result is plausible.

That's great advice. I make my basic electronics class students predict what a meter reading should be BEFORE they go poking the leads into the circuit. We also discuss what strange meter readings can mean.

In the IATSE Local 481 Power Quality Workshop I developed we do an exercise where the students meter the voltage and current on a putt-putt generator (non-inverter type) while running a non-pfc 2.5kW HMI light.   Since, invariably, the meters brought by the students range in quality, the readings they get range from being 84% over to 40% under what they should be. We then so the same exercise with tungsten lights dimmed on a Strand pack and find the results range from 13% over and 16% under. The discrepancy in the results is a good jumping off point for a discussion about how meters work and that they can be mislead by distorted waveforms. To see why use this link: http://www.screenlightandgrip.com/html/emailnewsletter_generators.html#anchorMeters

Guy Holt, Gaffer
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Frank DeWitt

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Re: DMM suggestions?
« Reply #25 on: December 11, 2017, 02:58:40 pm »

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« Last Edit: December 13, 2017, 05:53:02 pm by Frank DeWitt »
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John Roberts {JR}

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Re: DMM suggestions?
« Reply #26 on: December 11, 2017, 03:14:52 pm »

Since I just bought a low/mid range Fluke (107), and a low end chinese wonder I looked at the specs for a chuckle.

The Fluke specs something like +/- 0.5% with no other qualification besides a 0.1% tempco.

The cheap meter spec'd a similar +/- 0.5-0.8% basic accuracy in DC range but with a remarkable +2 or +3 (%?) If it 3% high the 0.5% basic accuracy doesn't much matter.

AC is worse with +/-2% + 10 (%?)

So on paper still better than Guy's experience. I suspect most of his students errors are due to squirrely rectification and frequency response, but you would hope even cheap meters target response to be correct for 50-60 Hz.

JR
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TJ (Tom) Cornish

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Re: DMM suggestions?
« Reply #27 on: December 11, 2017, 03:16:10 pm »

A old topic but I think worth bringing back for a nice meter find.  Eventek ET820 Digital Clamp Multimeter $25.69 on Amazon.  What sold me is the 2 amp full scale clamp on range.  Nice for finding ground loops.  It also has a built in NCVD and a lighted readout and a flashlight.

I still love my Fluke multimeter but this cheep meter will be the one in my Gig bag.

https://www.amazon.com/Eventek-Auto-ranging-Multimeter-Non-contact-Capacitance/dp/B06Y5W19F9/ref=sr_1_sc_1?ie=UTF8&qid=1513021787&sr=8-1-spell&keywords=eventex+amp+meter
This meter claims no safety ratings (at least on the Amazon page).  Maybe I'm cynical, but $25 doesn't seem enough money for the safety features I want if I'm metering line voltage - especially a high-current source.
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Frank DeWitt

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Re: DMM suggestions?
« Reply #28 on: December 11, 2017, 04:48:34 pm »

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« Last Edit: December 13, 2017, 05:53:24 pm by Frank DeWitt »
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Frank DeWitt

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Re: DMM suggestions?
« Reply #29 on: December 12, 2017, 08:12:12 am »

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« Last Edit: December 13, 2017, 05:53:43 pm by Frank DeWitt »
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