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- เผยแพร่เมื่อ 29 ต.ค. 2024
- How Dave checks the "calibration" of the multimeters in his lab.
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Wow David, Can't believe your HP meter and the voltage reference were both accurate to 5 decimal places right out of the box. What excellent examples of high quality engineering they both must be
Time and patience. It's MUCH harder being in Australia too, as shipping costs suck, and many don't ship here.
That's ok, start cross-checking them and keeping a log to see if they drift. When you get a chance, compare one against a better meter and see how it shapes up.
Nice introduction but where is the calibration process?
Yoram Stein : thatwhat I was hoping for.
Usually a precision Zener diode reference. Some labs use mercury/silver oxide/zinc air batteries as their voltage is extremely stable over the life of the battery.
Quality people love calibration. The last electronics CM I worked for bought a few cheap DMM's for test technicians, then was paying double what the DMMs are worth each year just so they have a valid calibration certificate. Our quality manager had never seen or heard of a "No Calibration Required, Not to be Used For Conformance Testing" label before and thought everything always needed to be "in-calibration". Many calibration houses will not even tell you what they needed to do (if anything) to calibrate a meter, or how much the meter was off.
Another excellent and useful video, thanks Dave!
Thanks Dave, much appreciated.
No data could be used for reports or documentation, However could still use the test equipment when calibration was not required. I would issue that type of test equipment when no precise testing measurement was required. Working at a calibration lab for the Navy.
It used to be standard cells with a well defined cell potential. Nowadays I think that something called the Josephson effect is still used for standards. A Josephson junction is a superconducting junction that you can apply a DC voltage which will produce an oscillating current over the junction at a frequency dependent on the applied voltage. Luckily the reverse is also true. An applied AC current will produce a DC voltage which is dependent only on the frequency. Not the current magnitude.
Let’s say you have a standard that is accurate to 10.00000. Now you want to calibrate a DMM to 10.00. Should you (1) turn the adjusting potentiometer until the display is flickering between 9.99 and 10.00, or (2) turn the adjustment until there is a solid 10.00 on the display?
Dave, what is calibration at all?! Does they trim some pots or some stuff to bring up meters to spot on, or they just tell you how much you are off from the actual value and you have to keep that in mind while using your stuff?! CMON DAVE!
Hi, i have a fluke multimeter, and we sent them to be calibrated, but the lab returned the DMM with blown fuse, is this normal during calibration?
Edward Carnby They checked if the fuse is still in its nominal specs :D
Surely not.
Have a question about the resistors. I see those ones you have in your calibration device you built cost like $15-25 a piece! WOW!
I was wondering. Can't I just take a cheap penny 10k resistor down to my electronics shop and have him record the exact reading they get with their 6.5 digit meter, onto a piece of paper? Then when I make the little black box with handy connectors like you've done, I just write down the recorded reference value and compare meters to that number? Would save a lot of money that way at least.
Nope, resistor can drift with time and will drift with temperature and humidity. You need at least a stable one to do this. If your electronics shop does this measurement for free you could give it a try with a low tempco, stable resistor but it will be in the couple of bucks range at least.
Keep in mind that it'll last a lot of time and it's very high precision. If you want, you can buy a slightly worse one. You can use parametric search and order by price. And remember to check that the minimum quantity is 1! I would use Digikey since they have very good parametric search, and if the order is more than 50 €/$, you have free shipping! You can order two of those and have free shipping.
well brand new DMMs are calibrated at factory yes but wierd things can happen, and happened to me one, I bought a 6 1/2 digit DMM for work with calibration certificate etc. and 4 months after that a calibration team came to the site to perform on-site calibration and I put this DMM on the list, they told me there was not need to calibrate because it was purchased 4 months ago, I of course insisted and yeah next day they were shocked that frequency measurement was off by ~50KHz in the 300KHz range, what could happend, something in the shipping? I don't know :)
I've always wondered, isn't this a chicken and egg problem? Is there a standard to calibrate your standards to?
Sorry, no idea how that would have been. I was just playing around with my DC standard the other day and thought I'd brag about the 1.00000 reading :->
at least your honest bud lol
which accuracy is needed for modern digital electronics?
By its very nature digital doesn't require much accuracy at all. Analog is much more critical. For instance, when you use an IC at 2Vcc, a HIGH input signal can be anywhere from 1.5V to 2V. And LOW input is anywhere from 0V to 0.5V. (data taken from an NXP 74HC595 datasheet) So in order to check those signals you don't need any accuracy at all. For digital, being able to capture *sequences* of voltages is much more important. You'll find yourself switching to a logic analyzer and/or oscilloscope instead of a multimeter very quickly when you start working with digital signals.
@@ArumesYT Yeah, I know. Just curious where it is needed in modern digital world. Rf design?
question in some multimeter models there is no contonuity function and diode measurement it is possible to add this function as in the case of the multimeter HP3468A
10 years later any any kind of electronics gear is now expensive as hell
So how do I calibrate my hp3478a? I was under the impression that you'd show us how it's done.....
You need a pocket screwdriver to put it in CAL mode, shorting straps for front & rear terminals, and $$$ of AC, DC and Resistance standards. AC is the worst because "complete" CAL requires 280 VAC @ 100kHz, and 25VAC @ 300kHz ref 😆.
At some point someone would have to manually count the electron flow :)
the absolute accuracy doesn't matter because it can be compensated for by calibration, right?
Nice! Dave is this the 2nd or 3rd video I've inspired? (or am I crazy?!?!?!?)
Could it be that older high end references and multimeters are very stable because they are "burned in" by years of use?
I found an article I had purchased from Silicon Chip talking about a 5V precision Reference using a Maxim MAX6350. I think I've seen similar articles elsewhere. I've always wanted to build one but never got around to it. What do you think? Could I use the MAX6325, MAX6350 as a poor hobbyist calibration standard?
Thanks guy
What natural reference does a calibration lab use for the industry standard ?
This may indeed be my most costly video to date!
That's it i'm off to calibrate my meters, Shit i don't have a DC voltage standard ........
Wow the resistor is now 72bucks! My eyes hurts ...
What’s the main difference in a 3468 and a 3478?
They wanted it to go to 11 but their bosses wouldn't let them, so they made it so it would go up to ten point ten.
That is very accuate. where do you actually need that? I mean, you have a wide Voltage tollerance on almost anything of at least over 1. Where does this actually come in handy?
This video cost Dave a hot sweaty summer in his lab. ;)
Hi, David, please let me know if you have an EDC MV-106 to sell or where I can to Find this! tank you by help!
Easy, grey beard tongue angle! In nature nothing is more accurate.
Can you measure 100 to 500 nano volts?
thanks : )
The way you can dial up "10.1010101010" using the knobs is messing with my head :)
There are standards made just for check instruments ....
need v ac ref... please
I upgraded form a 10$ meter to a Agilent U1241B :D
Yada yada yada, waste of my 14.31 minutes and still no shit been done. Thanks mr show off.
Josephson junction
i got a wavetek datron 9000 on sale, anyone interested ?
Id call the unit a secondary std
Watching that reversed Z is like growth hormones for my OCD.
blah blah blah ...and the calibration process ?
pshh, fluke 45 bench meter all the way dave!
first