| Products > Test Equipment |
| Forced Revision DMMCheck Plus |
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| J-R:
--- Quote from: KungFuJosh on January 25, 2024, 02:58:15 pm ---Is the voltage standard only ~5V? I'd love to see a standard that covers multiple ranges including mV. --- End quote --- C'mon man! The voltage info is in the specs! There are at least a couple ways to tease out some additional lower AC & DC voltages from the DMMCheck Plus. Easiest to set up and calculate is to use the current source combined with the 100 Ohm resistor to generate a precise voltage near 100mV (calculate the exact value from the calibration sheet). This can allow you to verify the mV range on a lot of DMMs. The current source tops out at around 500mV, so you can't do this with the 1k Ohm resistor, though. Less than ideal but can be done is to use all four precision resistors with the 5V reference to make a voltage divider. This drags the 5V down a little bit so you will want to measure it or your calculations will be off. This yields individual values of approximately: 4.5mV, 45mV, 450mV, 4.5V. When calculating the voltage drop across each individual resistor, be sure to include the DMM resistance since it will be in parallel, but only with that one resistor at a time (unless you have four DMMs!). Some helpful calculators: https://3roam.com/total-resistance-calculator-parallel/ https://3roam.com/voltage-divider-calculator-with-4-resistors/ Ultimately, if you want to take things very far you will need to purchase some additional equipment. In my opinion the easiest solution is to just have a better & calibrated DMM rather than trying to have every imaginable reference. |
| KungFuJosh:
--- Quote from: J-R on January 26, 2024, 03:30:48 am --- --- Quote from: KungFuJosh on January 25, 2024, 02:58:15 pm ---Is the voltage standard only ~5V? I'd love to see a standard that covers multiple ranges including mV. --- End quote --- C'mon man! The voltage info is in the specs! Ultimately, if you want to take things very far you will need to purchase some additional equipment. In my opinion the easiest solution is to just have a better & calibrated DMM rather than trying to have every imaginable reference. --- End quote --- Cute unsolicited opinions. However, the point of a good reference is to verify your DMM's calibration. I have two calibrated bench DMMs that don't agree in the low mV range. Playing games like you suggest, and using other components doesn't result in a calibrated/reliable reference, and is useless in this case. Before I asked the question, I looked at the page OP linked, and there was literally no specs for voltage listed. In general, the information on the product page is inadequate. The only voltage listing was on the cal sheet another user posted in this thread for a previous device version. Have a pleasant day. |
| alm:
--- Quote from: KungFuJosh on January 26, 2024, 01:09:37 pm ---Cute unsolicited opinions. However, the point of a good reference is to verify your DMM's calibration. I have two calibrated bench DMMs that don't agree in the low mV range. --- End quote --- To fully verify calibration of a DMM, you need a multi-function calibrator that covers all ranges and functions (from mV to 1000 V). This device offers a few useful voltage, currents, resistances etc to spot check a DMM. There are other devices (that would be off-topic for this thread) that offer adjustable voltage sources that may be more suitable for your particular task of adjusting the mV ranges. --- Quote from: KungFuJosh on January 26, 2024, 01:09:37 pm ---Playing games like you suggest, and using other components doesn't result in a calibrated/reliable reference, and is useless in this case. --- End quote --- Actually most voltage references offer just one proper output and are used together with other ratio devices to cover other ranges. With good metrology practices, like a Hamon divider, you can transfer between ranges (e.g. 5 V and 500 mV) with a low uncertainty. --- Quote from: KungFuJosh on January 26, 2024, 01:09:37 pm ---Before I asked the question, I looked at the page OP linked, and there was literally no specs for voltage listed. In general, the information on the product page is inadequate. --- End quote --- Try clicking on the "learn more" button near the top that links to this these specs. |
| KungFuJosh:
--- Quote from: alm on January 26, 2024, 06:27:58 pm ---Actually most voltage references offer just one proper output and are used together with other ratio devices to cover other ranges. With good metrology practices, like a Hamon divider, you can transfer between ranges (e.g. 5 V and 500 mV) with a low uncertainty. --- End quote --- Yes, but the important factor here is that whatever is in the circuit is permanent, and calibrated. Without the specs on paper, there's nothing to trust. |
| Martin72:
--- Quote ---This device offers a few useful voltage, currents, resistances etc to spot check a DMM. --- End quote --- And that's exactly why I bought the checker, which already has its purpose in its name. |
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