batteryless panic alarm

Discussion in 'General Electronics Chat' started by batteryless, Feb 20, 2011.

  1. batteryless

    Thread Starter New Member

    Feb 19, 2011
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    Presently panic alarm works with battery so i need to make it batteryless can any one suggest where the portable button device needs to work without battery.
     
  2. SgtWookie

    Expert

    Jul 17, 2007
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    What's wrong with using a battery?

    Do you want to plug it into a wall outlet instead? I hope you like long extension cords.
     
  3. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    :D:D:D


    Solar panel? Wind up generator?

    Maybe he wants to use a miniature over unity device? :confused:

    I like the OPs forum name too. Must be a theme. :)
     
  4. batteryless

    Thread Starter New Member

    Feb 19, 2011
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    actually its a project need to make a batteryless panic alarm using alternative sources
     
  5. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    Well no one is going to be able to help you if you don't mention what your "alternative" source is going to be. You need to be able to power the device somehow.

    How do you plan to store the energy to power the device?
     
  6. tom66

    Senior Member

    May 9, 2009
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    Do you mean solar power or some other renewable source? You will probably still need a battery for when this is not available.
     
  7. Adjuster

    Well-Known Member

    Dec 26, 2010
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    A loud whistle, to be blown by the user? What about some kind of compressed air horn?
     
  8. bradstormer

    Member

    Aug 6, 2010
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    i have seen these torches where the power supply consists of a storage device, most probobaly a capacitive cct, which recieves its power from being shaken. when shaken a magnet moves through a coil generating electricity. i think the law governing it is called farradays law though i could be mistaken.
    so in a nutshell
    a magnet moves through a coil to generate electricity
    electricity stored in a capacitive circuit with a large time constant (time taken to fully discharge the capacitor).
    so with a slight alteration, such as the addition of a switch you could have your circuit working for a short period of time without a battery
     
  9. batteryless

    Thread Starter New Member

    Feb 19, 2011
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    for storing the power i thought of using a super capacitor bt i need only to power the device by using a alternative source if possible a circuit diagram
     
  10. Adjuster

    Well-Known Member

    Dec 26, 2010
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    This sounds like homework / coursework.

    @ batteryless: What circuit ideas have you come up with so far?
     
  11. bradstormer

    Member

    Aug 6, 2010
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    well the power supply is litteraly just a coil of wire with a magnet that can be slid through it, so there is no real circuitry unless you are worried about generating too much voltage, in which case the addition of a zener diode should suffice.
    you can actually find many of the necessary formula required to calculate the number of turns needed and the amount of magnetic energy required from sites such as hyper physics. all you do is put in a three pole switch, one setting to charge the capacitor, one to activate the device and one to turn it off, hence storing the power.
     
  12. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    So you plan to have a panic device that is powered by something you have to shake to make it work????


    As a poster above pointed out, a whistle or airhorn would be far more reliable.
     
  13. beenthere

    Retired Moderator

    Apr 20, 2004
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    With respect to supercaps, a battery has many times the energy storage capacity, and the ability to discharge it at a constant voltage level.

    How about some more information on the requirement?
     
  14. batteryless

    Thread Starter New Member

    Feb 19, 2011
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    i jst have a device that works with battery i need to implement that without using a battery for storage device i thought of using a supercapcitor and for energy i thought of using a nano wire technlgy
     
  15. batteryless

    Thread Starter New Member

    Feb 19, 2011
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    can anyone give me ideas
     
  16. bribri

    Member

    Feb 20, 2011
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    ha! best answer.
     
  17. Adjuster

    Well-Known Member

    Dec 26, 2010
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    To make the best use of the energy stored in a capacitor, despite the falling voltage during discharge, requires a switched-mode regulator. Even with this arrangement, the available energy will be limited. Note that a typical miniature "super-capacitor" has a relatively high equivalent series resistance, which will result in greater losses when the capacitor discharges quickly.

    Before wasting too much time on this, do a feasibility study: find out how much power is needed by your alarm sounder, and how long this is required for. Multiply the power in Watts by the time in seconds to get energy in Joules. From this you can get an idea of how big your capacitor would need to be: the energy stored in a capacitor is 0.5*C*V^2.

    Most likely the result will be disappointingly large, especially given that very big capacitance values are usually only available in low working voltages. For a practical design, you would also need to allow for losses in the capacitor and the voltage converter.
     
  18. GetDeviceInfo

    Senior Member

    Jun 7, 2009
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    or screaming.
     
  19. cjdelphi

    New Member

    Mar 26, 2009
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    Seriously.... the Cap will discharge after a few days anyway making the alarm very quiet...

    So i'd probably opt for for a small solar panel (like they use on the cheap toy cars) a couple of dollars at most, seen loads about. and use that to charge a super cap, use a diode to prevent the cap from discharging back into the cells, this should be enough along with a piezoelectric speaker, but I can't imagine it lasting very long... he/she would be better off screaming for what good it would do them and hitting them :D
     
  20. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    What power source did you intend to use? Movement? Solar?

    Do you have some "nano-wire" laying around?
     
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