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Why most multimeters range is 2v 20v 200v instead of 9v 99v and 999v
Why most multimeters range is 2v 20v 200v instead of 9v 99v and 999v
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Old 27th October 2017, 11:21 PM   #21
leadbelly is offline leadbelly  Canada
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Why most multimeters range is 2v 20v 200v instead of 9v 99v and 999v
Quote:
Originally Posted by infinia View Post
Remember the absolute accuracy is not important, after all it is matching or finding the differences or ratios. So using the same meter and range most measurement error terms are nulled.
Even then a 1% DMM in resistance function gives good enough accuracy to meet the same gain error budget using expensive 0.1% parts.
Don't understand your point. If 2 resistors both read 47.5k on a 3.5 meter, they are both between 47.45k and 47.54k according to the meter's precision. That can be a 1.9% difference.

EDIT: Oops, too hasty with the calculator, I see your point.
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Last edited by leadbelly; 27th October 2017 at 11:31 PM.
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Old 27th October 2017, 11:25 PM   #22
leadbelly is offline leadbelly  Canada
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Why most multimeters range is 2v 20v 200v instead of 9v 99v and 999v
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Originally Posted by GoatGuy View Post
My reply could lead to another thread. One of my deepest pet peeves in the audiophile world - especially by those who can't/don't/won't actually pursue the math.

Basically “spec'ing ultra precision resistors” from the belief that “precision” ≡ improvement in sound. I've had (sheepishly) ridiculous arguments with highly opinionated people in this area, and the idea just beggars belief. And it persists.

Its like a religion. Founded on the patterns of tea leaves in teacups.

GoatGuy
You're not much into chip amps I see. You need that precision so that you can balance the load between chips. It's not religion. It's your calculator or simulator, if you have either of those
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Old 27th October 2017, 11:39 PM   #23
scott wurcer is offline scott wurcer  United States
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Quote:
Originally Posted by GoatGuy View Post

Seriously… be happy with your $5 (or in my case $29) 3½ digit multimeter.
I still have mine, well past breaking, there are no more stops on the range switch and I finally toasted a current sensing resistor. I still use it for everything (except current of course).

On the resistor precision thing, I agree, but would give some folks the benefit of the doubt if they think a resistor that could be manufactured to that precision starts with a better material which is generally true.
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Old 28th October 2017, 01:29 AM   #24
simon7000 is offline simon7000  United States
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For those of you who have a VTVM from days of old, just past the end of the 1.5 volt scale there is a small dot or tiny circle. It is at 1.56 volts. That is the open circuit voltage of an old fashioned fresh carbon zinc cell.

That allowed easy calibration of the meter.

Now the scaling was often 1.5, 5, 15 etc. as 5% resistors were often used in the range switch that limited the accuracy on higher voltage scales.

So it was not just the low cost range doubling that influenced the design of early digital meters. It was also a bit of habit.
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Old 28th October 2017, 02:14 AM   #25
Ultima Thule is offline Ultima Thule  Europe
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Originally Posted by TNT View Post
Thanks for the tip - ordered one!

//
Hi how much did you pay for the multimeter, I can only see "get quote" on their web page.

34450A Digital Multimeter, 5 1/2 Digit | Keysight (formerly Agilent’s Electronic Measurement)

ps. It's a pity it uses OLED, not good for static showing as they will risk suffering from burn in as the old CRT's.
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Old 28th October 2017, 12:43 PM   #26
suzyj is offline suzyj  Australia
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A lot of what you get in good meters is protection from abuse. I stuffed up once and put my Fluke 87 across 240V Active-Neutral in 10A range. Popped the breaker for the lab, blew the 10A fuse in the meter and shortened my probes by a couple of millimetres, but that was it.

Good meters, Flukes.
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Old 28th October 2017, 02:03 PM   #27
simon7000 is offline simon7000  United States
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Originally Posted by suzyj View Post
A lot of what you get in good meters is protection from abuse. I stuffed up once and put my Fluke 87 across 240V Active-Neutral in 10A range. Popped the breaker for the lab, blew the 10A fuse in the meter and shortened my probes by a couple of millimetres, but that was it.

Good meters, Flukes.
I of course never make mystakes. But I do keep a few fuses for my fluke meters. Turns out they are much cheaper if you buy them as a fluke repair part than from a parts distributor selling the same size fuse.

I do have to admit my high voltage voltmeter uses an analog meter as I don't really trust that there won't be a creep path to destroy a digital one. Also there is little possibility that the meter will stop reading due to a dead battery. Nice to know when it is safe to touch the circuit under test components.
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Old 28th October 2017, 02:23 PM   #28
TNT is offline TNT  Sweden
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Quote:
Originally Posted by Ultima Thule View Post
Hi how much did you pay for the multimeter, I can only see "get quote" on their web page.

34450A Digital Multimeter, 5 1/2 Digit | Keysight (formerly Agilent’s Electronic Measurement)

ps. It's a pity it uses OLED, not good for static showing as they will risk suffering from burn in as the old CRT's.
I got a Paypal option etc... added one to the "basket"... the normal procedure...

Aha -I got mine from Banggood

//
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Old 28th October 2017, 05:02 PM   #29
GoatGuy is online now GoatGuy  United States
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Originally Posted by leadbelly View Post
You're not much into chip amps I see. You need that precision so that you can balance the load between chips. It's not religion. It's your calculator or simulator, if you have either of those
Hey there… since I'm willing (and able) to both learn and “do the math”, may I ask a favor? Post a schematic of a circuit (or a thread, or whatever) that shows how such precision current-sharing / load-sharing resistors are deployed.

I'm good with the math, so I'll spend the time thinking on this mathematically.

Thing tho is, it remains almost entirely untaught in our schools, whether pre-college or in-college, the difference between significance and precision. So many times (in journals, the news, Wikipedia, here at DIY and so on), do I see the problem.

The square-root of 2.0 Ω is 1.414214 Ω. Mmm… no! Its 1.4 Ω. The || average of a 47 kΩ and a 63 kΩ = 26.9182 kΩ? No… 27 kΩ would be just fine in the context. It takes knowing that both 47 and 63 are “standard values” in the 10% and 5% E–12 and E–24 nominal resistor lineup. Not 2% (E–48) or 1% (E–96) or 0.5% (E–192) or 0.1% (no E-designation). The 27 value is also in both the E–12 10% and E–24 5% resistor lineup.

Anyway… I look forward to see a schematic or linky that gets my thinking a-going. Don't like being a dinosaur!!!

GoatGuy
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Old 28th October 2017, 05:20 PM   #30
Mooly is offline Mooly  United Kingdom
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Why most multimeters range is 2v 20v 200v instead of 9v 99v and 999v
Despite having some half decent meters, I always keep this handy in a drawer. Note the high quality test lead terminations on the meter Just be careful how you grab hold.
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