EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: rwgast_lowlevellogicdesin on August 14, 2015, 05:18:46 am
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Man this is a hard topic to find on .....google for some reason the search is "Shielding your DMM" provides 100s of links about shielding a guitar, DMM EMI shielding is also not very helpful.
I just watched a 15 50 to 70 dollar meter shootout on yoututbe, both meters I own were included, the Klein MM2000 and the Extexh 430 were reviewed and they had no shielding, Im just curious to know whether shielding a meter makes a huge difference in a normal setting, I mean is my microwave inducing RF in to the meters ADC?
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Im just curious to know whether shielding a meter makes a huge difference in a normal setting,
It might, the original poster never did the tests I asked for in the final post, but his old meter couldn't read TV plasma voltages properly and it may have been due to lack of shielding?
http://www.badcaps.net/forum/showthread.php?t=43396 (http://www.badcaps.net/forum/showthread.php?t=43396)
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I mean is my microwave inducing RF in to the meters ADC?
Not you microwave... but probably your mobile phone. ;)
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So if I solder a spring to the ground of the PCB, or common jack and use some hoe depot foil tape to cover the inside would that be ideal, or at least much better? What about feright clips on the probes, or is that totally unnecessary?
Also what about probing High Energy? If you shield everything then probe 1000v wrong, will the electricity conducting through full sheilding cause a bigger blast? I ask this becuase Im trying to get in the electronics Low Voltage business but I am an industrial sparky and I dont want to probe a 480 switchgear or 1000v worth of solar panel, drop my lead and make a bigger blast...... So I guess im wondering if I should only shield meters I use at 120v or less, for projects and not my big boy 1000v.
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As soon as we started to hand multimeters, immediately followed by 1000 volts.
Meaning of the theme is lost.
Lord, where do you find all this in the domestic environment?
You are not interested in general safety, rubber gloves, rubber boots, double insulated wires?
Why replace over concepts exist kilovoltmeters.
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@measurementpoit
Im not really sure what you are trying to get at? When doing industrial work and commissioning I wear a full suit. But Im not going to suite up to check a panels incoming lines or a higher voltage switch gear... plus im not even talking about shielding in meters in this case, im more referring to RF projects.
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I had no intention to offend. It surprises me wagging concepts. Or the combination of concepts - to measure more accurately - no stable voltage or from a multimeter to measure the manual from 1000 volts. Can a horse to jump up to 5 meters from the spot.
1) In the areas of radiation, we must first think about the person, not on the multimeter ...
2) Speaking of screens and screening should imply a closed circuit. The multimeters is tissue paper and two pieces of sheet metal. I have no good reason to distinguish between what the meter shielded.
3) Scope and method of application. It is always silent. And this is important. Application method - parallel connection? So it is making a point of measurement of external RCL. And the antenna wires are for incoming circuits multimeter.
4) I always work in the area of ??GSM communication. The impact of this on the meter, I had not noticed. Quite a different matter when measurements are made in electronics having generators, data, inductors, pulsations - there were cases not explained by the behavior of perfectly good meter. These cases are not common.
I say that performing measurements in low voltage or pulse circuits - demand the impossible from the multimeter.
5) In areas of strong radiation zones or high-voltage lines - it is a matter of health. This is not a multimeter.
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The shielding in DMMs is for EMC. "Lower" frequency clocks, e.g. < 100 MHz, and good board design can minimizes EMI or susceptibility enough that shielding isn't necessary. Also, there are conductive plastics or paint that can be used in lieu of obvious looking metallic shields.
http://www.rtpcompany.com/products/emi-shielding/ (http://www.rtpcompany.com/products/emi-shielding/)
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I have a few "el cheepo" DMMs, at the "10 dollar price point". The ones from Harbor Freight, "Cen-Tech" brand, have a shield, a layer of metal foil on the inside of the rear case half that connects via a spring to the PCB ground. Another one from somewhere else, "Excel XL830L" has no such shield. The Cen-Techs are definitely less responsive to EMI in the near vicinity.