Reading multiple voltage inputs at once

Discussion in 'General Electronics Chat' started by fireftrmike, Nov 21, 2014.

  1. fireftrmike

    Thread Starter New Member

    Sep 15, 2011
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    I'm sure it's out there...... Looking for something that can be installed on a piece of equipment that can read multiple voltages at once for troubleshooting. Looking for something that stores the values (like a scan tool can do for auotmotive industry) for looking at later after an event has happened. (can be stored on PC/smart phone maybe?) I have some radio controlled equpment that drops offline intermittently. The event is hard to catch. Would also be interested in resistance readings. (that are also stored) Thank You
     
    Last edited: Nov 21, 2014
  2. cmartinez

    AAC Fanatic!

    Jan 17, 2007
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    The expensive option would be to use an oscilloscope, of course... on the other hand, you could buy a bunch of multimeters with RS232 output and log their readings on a computer...
    Are the signals you're trying to monitor analog or digital? What's the voltage range you're trying to monitor?
     
  3. fireftrmike

    Thread Starter New Member

    Sep 15, 2011
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    Sorry that would be important info... analog less then 20 volts
     
  4. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    What kind of signals are they? The event could be so fast that you will have trouble finding anything with data loggers, multimeters and other slow measuring tools.
     
  5. fireftrmike

    Thread Starter New Member

    Sep 15, 2011
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    Mobile equipment/crane.
    Automotive voltages. My fluke has recorded high and low. But was looking for something I could view after a operator clocked event. Was looking for shotgun approach....several inputs. But just one would be ok
     
  6. cmartinez

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    You mean important info as in "confidential info"? If so... that's ok, no one understands the need for privacy better than me...
    But let me ask you two basic and important questions (that you don't HAVE to answer, if you don't want to):
    1. How much would you be willing to spend for such an instrument?
    2. How many units of this instrument would you need?
     
  7. MrChips

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    Oct 2, 2009
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    This is common equipment in the electronics field used for trouble shooting and diagnostics.
    However, before we can narrow down your specific need you have to characterize your signals.

    1) What is the range of voltages to be monitored?
    2) How rapidly are the signals changing, i.e. frequency or bandwidth?
    3) What time resolution are you interested in measuring? For example, what is the time between the recorded trigger event and the time when a failure is recognized? Another way of putting it, once the failure event is recognized how far back in time and at what time intervals do you want to record data?
    4) How many different signals to be simultaneously recorded?

    For starters, a standard digital 100MHz oscilloscope to record two channels costs under $2000.
    A 600MHz logic analyzer, to record 64 channels can run you $15000.
     
  8. cmartinez

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    Aaaaaandddd THAT pretty much sums up why I asked my first question about your budget... :D
     
  9. MrChips

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    Oct 2, 2009
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    cmartinez likes this.
  10. cmartinez

    AAC Fanatic!

    Jan 17, 2007
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    :eek:

    Considering that piece of (very) valuable info... perhaps one could put together a bunch of cheap-o USB oscilloscopes (such as this one, or this one, or even this one) working in parallel using a common external trigger source...
    In the end it would all come down to computer power and how many events the oscilloscope's software is able to record (and of course, the osc's frequency response, among other things) But MAYBE one could end up with a system far more affordable than the $75K Rolex that you just mentioned... Although I'm sure there must be a rather solid set of good reasons why that piece of jewelry is so expen$ive...
     
  11. fireftrmike

    Thread Starter New Member

    Sep 15, 2011
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    Thanks everybody. LOL I thought surly there was a widget that could hook to a circuit that could store information for me to look at later that would be inexpensive. I'm a mobile heavy equipment mechanic and have alway thought it would be nice to have something I could hook onto a circuit and let it run while I'm off doing something else. My thought has always been that my customer would say "it just did it" and I could walk over and tap on the screen and back it up to the event and get some usefull information and see what dropped off or didn't and move to a different circuit. Most of the intermittents happen several times a shift so the device wouldn't have to record forever.....just be hooked up while I'm with the customer. Then I could start splitting the circuit down. We have so many connectors in, around and under that chassis anymore that intermittents are common.
     
  12. MrChips

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    Oct 2, 2009
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    The professional equipment that sell for $15K-$75K are just extreme examples.
    You could throw together a data logger for under $300.

    But first please read my #7 post.
     
  13. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    You don't really need a datalogger (sample every 0.xxx seconds). You can also have an event logger, sample every time voltage exceeds x.xx volts. Both should be readily available and cheap.

    Note: The event logger is based on a comparitor and will trigger even the shortest a orations.
     
  14. fireftrmike

    Thread Starter New Member

    Sep 15, 2011
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    Range of voltage 20v DC or less
    Just looking for a momentary drop off or open of that voltage while unit is flexing/vibrating.
    Time resolution? Since I'm close by typically, it could simply record from event till I get there. Usually in minutes.
    One input (and maybe my fluke could do this with its "stored" high/low setting?) would be fine. I was just looking for multiples to speed things up troubleshooting wise.
    In the automotive/truck field they have scan tools that do what I'm thinking about so I thought maybe there was something like that in a hand held that could be wired in circuit...
    Working in the field for many years it's a subject that has come up before on many a job site. Maybe you guys can make something. Should be money in it if it's small, rugged and fairly inexpensive. Intermittent electrical issues are part of my every day job now. Nothing is more frustrating than the operator that calls you over for a downed unit only to have me start it up and run it for several minuted with no issues noted. If it's not BROKE it's hard to fix to if you know what I mean.

    Thanks for replies everybody. .....now I got a gearbox to finish rebuilding.....

    Mike
     
  15. MrChips

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    When we do electronic systems debugging we want to know what conditions and events led to the system failure.

    Typically, we look at environmental triggers such as temperature, pressure, humidity, vibration, AC mains brownout, power supply under/over voltage, EMI, ESD, data communication loss, dropout, corruption, parity error, etc., etc.

    Typically, we are not looking at minutes of recording, but milliseconds and microseconds, with time resolution in nanoseconds.
    Hence we would be looking at about 100 microseconds worth of data recorded at 10ns intervals, i.e. at 100MHz sampling rates.
    That works out to 10,000 data points per channel.

    That is the reason why we need to know the environment and the kind of system failure you are experiencing.
    Looking for a motor bearing seizing up and a computer crashing are two vastly different examples of system failures.
     
  16. profbuxton

    Member

    Feb 21, 2014
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    A really inexpensive option is one I used sometime ago to track logic faults. A one word (16 bit) logic analyzer.
    Just 16 registers triggered by one input and driving leds. Was based on CMOS logic so could be used for 5V or 12V signals. Was selectable for positive or negative triggering.
    Also I believe Texas or is it Tektronixs had a word trigger unit for a OScope which did the same thing. But it only triggered the scope trace when a word was recognized. i think I still have it somewhere.
     
  17. fireftrmike

    Thread Starter New Member

    Sep 15, 2011
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    Mobile equipment/Crane.
    Enviroment..... whatever mother nature throws at it. ( Have issues in ALL seasons ) (being VERY close to radio towers is a known issue)
    Most units are rural.......in the middle of nowhere though
    Hetronics radios. Functions drop off during a pick. Have to resync often. Different radio (loaner radios) same issue. Hard wire around slip ring to eliminate communication errors. Same issues. Thinking that it's having occasional ground connection or power issues as unit is vibrating/flexing. Only takes a blip to drop radio and have to resync. Many opportunities for connection issues as they have a lot of pin connectors in and under chassis. Not to mention lots of opportunities for intermittent shorts.
     
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