Author Topic: EEVblog #731 - Keithley DMM7510 7.5 Digit Multimeter Teardown  (Read 30454 times)

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Offline fonograph

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Re: EEVblog #731 - Keithley DMM7510 7.5 Digit Multimeter Teardown
« Reply #75 on: May 22, 2017, 12:19:20 pm »
how many measurements per second at 7.5 digit?
 

Offline niner_007

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Re: EEVblog #731 - Keithley DMM7510 7.5 Digit Multimeter Teardown
« Reply #76 on: May 18, 2018, 03:53:54 pm »
Those 18 bit 1MSPS AD7982s aren't cheap devices at approx $23 each @ 1K. Anyone got the faintest idea why they would have 2 of them?

I can't think of any good reason - they *could* use them to provide full rate 1MSPS digitizing with alternating autozero and gain calibration to avoid drift during long sampling runs but it seems very unlikely. In any case they could have used a single 2MSPS 18 bit AD7641 at $29. Also the manuals/specs don't suggest it does this.
DMM7510 has a secondary measurement function, for example it can measure voltage and current simultaneusly without a relay switch; it might be used for that, or maybe it's for its ACAL function

Maybe it uses one for the sense-inputs and one for the standard inputs (e.g. 4-wire resistance)
 


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