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tracking usage on power tool

Discussion in 'Electronic Design' started by Mike, Mar 20, 2006.

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  1. Mike

    Mike Guest

    Good morning.

    I'm looking to create a circuit in a somewhat small package to fit inside a
    power tool that would track how many times it was plugged in or had its
    trigger activated. Any method of reviewing the count is fine (prefferably
    inexpensive). I'm a novice in electronics, and so I'm looking for some help
    in a general design.

    Thanks,
    Mike
     
  2. John Fields

    John Fields Guest

     
  3. Mike

    Mike Guest

    When you say "power tool" are you talking about something like a
    Yes, 120VAC operated hand tool. Sorry for not including that.
     
  4. Guest

    You will want a small microcontroller and a bit of flash memory, either
    internal to the processor (if it can self-program) or as an external
    chip probably with a synchronous serial interface.

    You will need to write a logging routine compatible with the byte write
    but sector erase nature of flash memory. Probably you would do
    something like write a running count filling up the memory, and erasing
    the oldest sectors as you come close to running out of space. When you
    want to determine the count, you search the memory for the latest data.

    For reporting, you have to decide if you want to add a connector for a
    "computer" to read out the usage (a logic level serial port is probably
    simplest) or if you want a human to determine the count without added
    tools. For human interface, you could do something like morse code or
    beep count with a little buzzer inside, though you have to have some
    way of triggering that. Getting fancier with readout tools, you can go
    through the case plastic with an ultrasonic transducer, or modulate a
    data signal onto the charging jack, etc - but these are not simple.

    If only a few units are to be made, development cost dominates so
    convenient to program parts (seperate processor and SPI flash) may make
    the most sense. With a lot of units, their unit cost dominates and you
    will want to try to get everything in one small IC.
     
  5. Mike

    Mike Guest

    Would this be a good project for a PIC microcontroller? As far as the count
    readout,
    human readable is fine, so I'll look at what you suggested in more detail.
    Would morse code
    be easiest to implement?

    Thanks for taking the time to help.

    Mike
     
  6. John Fields

    John Fields Guest

    ---
    OK, what I'd do would be to go with a tiny microcontroller like a
    PIC 12F629/675

    http://ww1.microchip.com/downloads/en/devicedoc/41190c.pdf

    which has an internal non-volatile data EEPOM and a high-current IO
    you could use to drive an IRLED for reporting. Use another IO
    coupled to an IR receiver and you could use an IR remote control to
    talk to the tool and get data, erase data, etc. IR transceivers are
    available which would make it easy to implement the transmit/receive
    functions at the remote as well as at the tool.
     
  7. Mike

    Mike Guest

    Thanks John. I'll see what I can put together given the suggestions so far.

    Mike
     
  8. John Fields

    John Fields Guest

     
  9. Ian Stirling

    Ian Stirling Guest

    Would a meter that simply counted "on" hours/mins/secs when the tool was
    drawing power be of use?
    These are widely available as power meters, that are very cheap.
     
  10. Mike

    Mike Guest

    The meter would need to be enclosed in the case, so there wouldn't be
    much room, except for maybe a micro controller along with supporting
    components. Can you give me an example of what your suggesting?

    Thanks.
     
  11. Genome

    Genome Guest

    See... you am scum try to play printer ink game for 'Duh, my drill don't
    work no more.. must have buy new one'

    DNA
     
  12. Genome

    Genome Guest

    See... you am scum try to play printer ink game for 'Duh, my drill don't
    work no more.. must have buy new one'

    DNA
     
  13. Dirk Bruere

    Dirk Bruere Guest

    Not necessarily in the tool but attached to the power cord.
    Use a PIC etc to count the number of seconds power is applied by
    measuring field produced by current flow.

    Dirk
     
  14. Mike

    Mike Guest

    I understand. Thanks for clarifying.

    Mike
     
  15. Ian Stirling

    Ian Stirling Guest

    Err, no.
    A commercial power meter, that is used to check the energy usage of
    appliances, available for the equivalent of $10us or so.
    It plugs into the socket, and the power tool/whatever plugs into it.
     
  16. John Fields

    John Fields Guest

    ---
    You're welcome. :)

    Here's another thought: If you decide to go the IR way it would be
    no trouble at all to put a display on the remote (if you wanted to
    see the data there) or to retransmit it to an IR port on a PC for
    whatever reason you'd want to get the data into a computer.

    Nice little project you've got there!
     
  17. Dirk Bruere

    Dirk Bruere Guest

    I'm thinking that this is for hire tools where maybe useage means $

    Dirk
     
  18. Mike

    Mike Guest

    Hi Dirk. I was afraid of that idea coming across this thread. In
    reality, I'm known in my hometown for the power tools, and people always
    borrow them without returning them promptly as promised. So, I thought
    it would be to see how much people are actually using them :). I suspect
    one neighbor is using my tools on the job somewhere. I dunno... kinda
    bugs me out. :)

    You're not onto a bad idea there... next thing you'll see at home depot
    is rental charges based on the usage cycles, heh ;)

    Mike
     
  19. John Fields

    John Fields Guest

    ---
    How about for warranty validation?

    Let's say that I manufacture electric drills and I change my
    warrantee from 1 year to 1000 hours. A bad drill comes in six
    months after it was sold, with 2500 hours on it. With a one year
    warrantee on it I'd have to replace it, but with 2500 hours on it
    and a 1000 hour warrantee, I wouldn't.

    Let's see...

    That's my idea, but I disclosed it publically today, March 21 2006,
    so I've got a year to file for a patent before it goes into the
    public domain. Time to do a search...
     
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