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Cheap DVM with PC output?

Discussion in 'General Electronics' started by Lewin A.R.W. Edwards, Jul 1, 2004.

  1. Can I have a recommendation for a cheap PC-connectible voltmeter that
    I could get for under $100? I am testing a battery-powered device, and
    want to measure a couple of voltages over time (days at least, maybe
    weeks) to establish charge and discharge curves. Voltages to be
    measured are a pack voltage up to 33.0V, and a reference point that
    ranges up to 3.25V.

    Via ebay I found <http://www.technika.com/Sper/s840074.htm> which is
    nice and cheap but it's not clear what the RS232 interface does. What
    I want, ideally, is either for the meter to spit out the current
    reading every <n> seconds or for the meter to spit out a new reading
    with a timestamp when the value changes.

    Anyway, I MUST have the reading correlated fairly accurately against
    time - at least accurate to say 5 minutes per week, and the voltages
    themselves have to be precise to three significant figures. If the
    measuring tool is exclusively battery-powered it has to be able to
    last for two weeks' continuous operation.

    Ideas? Experience with the above product? Makes me wish for a good old
    strip-recorder :)
     
  2. Rich Grise

    Rich Grise Guest

    It says "Software Included," so it probably does exactly what you
    need and then some.

    Good Luck!
    Rich
     
  3. :( Unfortunately, they emailed me the manual and even that really
    doesn't answer the question. The software can display graphs of its
    own, but it isn't clear if it can just do a dumb raw text log like I
    want.
     
  4. :( Unfortunately, they emailed me the manual and even that really
    doesn't answer the question. The software can display graphs of its
    own, but it isn't clear if it can just do a dumb raw text log like I
    want.
     

  5. The Jaycar QM1538 is only $70 Australian, that's less than $50US, so
    surely you can find plenty of such cheap RS-232 meters in the US where
    I thought everything was half the cost it is here (even after the
    conversion!).

    http://www1.jaycar.com.au/productView.asp?ID=QM1538

    Regards
    Dave :)
     
  6. Yes, it looks very similar to the one I found. The problem is that
    there is not enough detail about what "logging" features it has.

    At work we have lots of these cheap RS232-connected meters. The
    software lets you "log" 999 samples of information, which is not
    enough for me (I want to sample at LEAST once every five minutes,
    better every minute). You can set the delay between slots. But you
    can't simply start a log that's appended ad infinitum. And because the
    meter uses a proprietary binary protocol you can't use a terminal
    program to capture an endless text log, either.

    I'd like someone to point me to a product that specs this feature
    explicitly, or give me hands-on experience notes...

    Thanks anyway.
     
  7. Rich Grise

    Rich Grise Guest

    How cheap do you need this thing?

    Check this one out:
    found at
    http://www.google.com/search?hl=en&lr=&ie=ISO-8859-1&q=rs-232+dvm&btnG=Search
    http://www.linuxtoys.org/dvm/dvm.html
     
  8. Rich Grise

    Rich Grise Guest

    My Pleasure! :)
     
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