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| Easy way to test the calibration of a DMM (Fluke 45)? |
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| CalibrationGuy:
Everything is relative and it all begins with your requirements. My clients produce military and space hardware. When you're flying in an aircraft, I'm pretty sure you wouldn't want it serviced or tested by people who have uncalibrated equipment of unknown origin. Having said that, let's see what we could do with a minimal budget. As suggested above, we could use a AA battery for the 1 volt range. A new battery would be in the 1.5v range. A 9 volt battery could test the 10vdc range. Put 10 9v batteries in series to test the 100vdc range. You could even select 10 resistors that are the closest match and build a divider circuit to test the millivolt range. Plug the meter into the socket and measure 120vac, but observe all cautions when working with line voltage. By being creative with a few resistors and batteries, you can accomplish a lot. Remember that ratios and relative measurements can get you very close to your goals. TomG. |
| shapirus:
--- Quote from: J-R on April 03, 2024, 08:26:43 am ---Side note, Doug has some budget $35 single-voltage references that could be of interest to some: https://voltagestandard.com/01%25-voltage-references --- End quote --- Unfortunately he doesn't. All the products in the "shop" section have been out of stock for a good while. |
| KungFuJosh:
--- Quote from: CalibrationGuy on April 03, 2024, 09:07:40 am ---Plug the meter into the socket and measure 120vac, but observe all cautions when working with line voltage. --- End quote --- I don't know anybody with wall voltage that's reliably on point, or stable throughout the day. I have to use a variac when I do circuit testing. |
| CatalinaWOW:
--- Quote from: CalibrationGuy on April 03, 2024, 09:07:40 am ---Everything is relative and it all begins with your requirements. My clients produce military and space hardware. When you're flying in an aircraft, I'm pretty sure you wouldn't want it serviced or tested by people who have uncalibrated equipment of unknown origin. Having said that, let's see what we could do with a minimal budget. As suggested above, we could use a AA battery for the 1 volt range. A new battery would be in the 1.5v range. A 9 volt battery could test the 10vdc range. Put 10 9v batteries in series to test the 100vdc range. You could even select 10 resistors that are the closest match and build a divider circuit to test the millivolt range. Plug the meter into the socket and measure 120vac, but observe all cautions when working with line voltage. By being creative with a few resistors and batteries, you can accomplish a lot. Remember that ratios and relative measurements can get you very close to your goals. TomG. --- End quote --- Those battery combinations can hit the right voltage ranges. But my observations indicate that new batteries have variability in their output of a few parts per thousand. Is that good enough? Only the user can say. |
| J-R:
--- Quote from: shapirus on April 03, 2024, 09:54:21 am --- --- Quote from: J-R on April 03, 2024, 08:26:43 am ---Side note, Doug has some budget $35 single-voltage references that could be of interest to some: https://voltagestandard.com/01%25-voltage-references --- End quote --- Unfortunately he doesn't. All the products in the "shop" section have been out of stock for a good while. --- End quote --- That's common for small, one-man shops, just check back later. |
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