rmh

is there any accurate method of determining the accuracy say to two places( .00) of present digital devices?
non loaded types ?

MR G

Reading battery voltage without a load is misleading.

Consider the voltage of a dead car battery...it will read 12 volts!!!

Voltage is not the power of the battery...Current is

MR G

JNorton

My Feedback: (2)

Dick,
Any calibrated DVM is capable of reading to two decimal places. Most new meters are close enough without being certified. If you buddy has a certified meter it pretty easy to parallel the meter to see how close the readings match.
Or am I missing the intent of the question?
John

richrd

If you are referring to calibration then yes there are lots of ways. The most cost effective way to calibrate DMM is to buy a reference cell.

BUT! I just googled for 15 minutes can not find what we used to use.
It was a single cell traceable to National standard Iam going back 20 some years now but it’s accurate to many places and all of are meters were referenced to it.

Maybe some one else will pipe in, The other way I set up calibration was to buy a precision meter good to 5 places then use it to calibrate the rest and every year send it to be recalibrated.
Rich

Cobra1

My Feedback: (42)

Just ask someone that has access to a FLUKE handheld meter and use it to do a comparison check. I ran a metrology lab some years back and we had several hundred Fluke meters to check calibration each year. It was rare to find one off by more than .001v. They are a pretty good standard.

rmh

I will check with the Fluke - also a mercury cell - the AE boys have to use a calibrated (yearly) meter -so I will check with one of them--

JPMacG

My Feedback: (2)

There are solid-state voltage references that are very accurate and quite inexpensive. I don't have the part number right now... I'll look it up when I get home. They are used in the same manner as a zener diode, but they are more accurate.

JPMacG

My Feedback: (2)

I am using a Linear Technology LT1029 5 volt Bandgap Reference. The data sheet says the output is pretrimmed to a plus or minus 0.2% accuracy with 20 ppm per degree C maximum temperature drift. You use it the same way you would use a zener diode - with a series resistor. If I recall correctly I got it from Digikey, Jameco or Mouser and it cost around $5 US.

There may be better voltage reference ICs available today - I have had LT1029 for about 8 years.

www.jameco.com www.digikey.com www.mouser.com