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Very long battery life devices

Discussion in 'Electronic Basics' started by Michael, Jan 28, 2005.

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  1. Michael

    Michael Guest

    There are battery operated radios (gas-meters, SCADA...) that are able to
    get many years out of a battery. I'm guessing they usually sleep and wake
    occasionally to transmit at full power using big capacitors. I need .75A
    for .5 seconds, several times a day. How do I go about doing this?
    (keeping the batteries (AA preferered) less than the size of a pack of
    cards, no recharging)
     

  2. Uhh... AA alkaline batteries can supply 750mA for 0.5s several times a day
    just fine. So what part are you having trouble with? It would be helpful
    to know allot more about what you are doing and what your problem is. What
    is your application, and what are the relevant voltages, etc.?
     
  3. A microcontroller can do this. It can keep track of time, using minimal
    power, and then wake up when required and enable your transmitter.

    Some of these (the rfPIC series from microchip, for example) have
    onboard transmitters that can be used to do the actual transmission,
    given an antenna.

    --
    Regards,
    Robert Monsen

    "Your Highness, I have no need of this hypothesis."
    - Pierre Laplace (1749-1827), to Napoleon,
    on why his works on celestial mechanics make no mention of God.
     
  4. Michael

    Michael Guest

    3.3V. I tried 4-AA going to a 7805 and it choked. I don't think 8 (4x2)
    would do the trick either. Do I need to charge a capacitor in order to
    suplly the 'burst' needed? How?
     
  5. Jeroen

    Jeroen Guest

    A 7805 uses 4 to 10mA of quiescent current already, so that's not the
    regulator to use when you're after low power. Preferably you should not use
    any regulator, but there are micropower regulators that don't use much power
    for themselves.

    Jeroen
     
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