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| I just bought a Data Precision 2480R Bench DMM |
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| EpicIntelGamer:
--- Quote from: c4757p on August 09, 2013, 03:59:09 am ---Just test the mA ranges. What is the highest reasonably accurate voltage you have? 50V across a 10k resistor is 5mA, and 10k is high enough that the burden voltage offset will not be too high. You can even measure it and compensate for it in your calculations. If you don't have such a high voltage you can use a lower one, you'll just need to measure the current shunt resistor and compensate for it. (You can use the meter to measure its own shunt. I see it uses shared jacks, so you can't do the "bridge ohms and amps" trick, but you can slide the case open and probe it. Just don't connect ground.) Calculate the current, don't measure it. Screw the A ranges, who the hell needs precision above 100mA anyway....? ;D The spacing looks proper to me.... Of course, I can't estimate small distances in inches for shit, but it does look like about 20mm... --- End quote --- I'm not sure what you define reasonably accurate. I have a variac and some 600v diodes and a 600v transformer so tecnhically I can get some pretty high VDC but I'm not sure if it has the accuracy you'd want. Other than that I have a hacked 7805 that can output up to 15v, that's about it. I'm nervous about all of this resistor business, I don't really ever go about using them for anything precise or with current. And as for your last statement of that paragraph, *raises hand* "uhh......I.........I.....do..." lol Most of the current ranges I ever measure are up in the amps, though now if I have the capability for mA, I guess I'll start using it more often. Hmm, I'm the opposite, can't estimate meteric even a quarter as precise as I can in imperial, and even that I'm not too good with. |
| c4757p:
Depends on how accurately you want to check it! Like I said, you just need to make sure nobody let their dog tweak the trimmers. No..... keep off the 600V, no need to fart around with that. I thought 50V because that what my highest-voltage "low voltage" PSU goes up to. Just use what you have and let Ohm's Law do the rest. Ha... I was kidding, after all, on my bench anything over about an amp is "oh shit, something's about to fry"... I can't estimate large things in metric and can't estimate short things in imperial! After getting used to working with PCB layouts I can even do a decent job estimating widths to the tenth-millimeter... But meters? Kilometers? Kilograms? Kiloanythings, really? Nope, I'm hopeless. |
| EpicIntelGamer:
--- Quote from: c4757p on August 09, 2013, 04:11:07 am ---Depends on how accurately you want to check it! Like I said, you just need to make sure nobody let their dog tweak the trimmers. No..... keep off the 600V, no need to fart around with that. I thought 50V because that what my highest-voltage "low voltage" PSU goes up to. Just use what you have and let Ohm's Law do the rest. Ha... I was kidding, after all, on my bench anything over about an amp is "oh shit, something's about to fry"... I can't estimate large things in metric and can't estimate short things in imperial! After getting used to working with PCB layouts I can even do a decent job estimating widths to the tenth-millimeter... But meters? Kilometers? Kilograms? Kiloanythings, really? Nope, I'm hopeless. --- End quote --- Aw I knew one of these days I'd be forced to learn about ohm's law, I guess that day is quite soon now. Think I might just hook it up to 600V just to see how accurate it is with probably the highest voltage I'll ever need to measure. Usually the only thing I measure are motors and other big things I'm working on, but I suppose I'll start to measure mA consumption of some of my circuits just out of curiosity. Later this month I plan to spend $100 to $150 on a really nice used Fluke portable DMM so maybe then I'll have something that is accurate and help me make this bench dmm accurate. I barely know meteric in general, and many imperial sizes confuse me. The only ones I've definitely got down is weight and distance measurement in imperial. |
| c4757p:
Ohm's law is... well, it's Ohm's law... That's it. It's about the most important "law" you'll learn in electronics, behind maybe Kirchhoff's laws - get familiar with it! |
| EpicIntelGamer:
--- Quote from: c4757p on August 09, 2013, 04:19:47 am ---Ohm's law is... well, it's Ohm's law... That's it. It's about the most important "law" you'll learn in electronics, behind maybe Kirchhoff's laws - get familiar with it! --- End quote --- That's not so bad, and will probably come in handy. All I know about Kirchoff's law is that current will flow equally along two wires or something like that. |
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