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Discussion in 'Electronic Basics' started by Abdul Ahad, Jul 11, 2003.

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  1. Abdul Ahad

    Abdul Ahad Guest

    New to Electronics and need some help...
    I want to add a micro-relay switch to my electronic personal organiser
    (which would have a tiny input of 0.2v and a minute current - which I
    can't even measure with my multi-meter). Basically, the electronic
    organiser has an alarm buzzer which goes on for 30 seconds at a
    pre-programmed time each day to wake me up. I want to add a tiny
    relay switch of some kind in place of the buzzer, which will act as a
    30 second interval timer to switch other external circuits on and off.
    Whilst the input voltage and current INTO this relay (out of the
    organiser) would be small, the flow through current and voltage in the
    external circuit - which is to be switched on and off by the relay -
    could vary as I want to use to switch a range of devices.

    Does anyone know what the range of specifications for such a relay or
    switch could be and where I can get this in the UK? The electronic
    organiser is powered by a 3v button cell, if this info is of use?

    Abdul Ahad
  2. Neil

    Neil Guest

    would it be an idea to use a small microphone mounted such that you can
    place the pda buzzer against or near?
    Then you don't need to get inside (risk of screw up!) the organiser itself.
    A small amplifier / comparator of some sort could then drive a relay, all
    powered externally.
  3. Abdul Ahad

    Abdul Ahad Guest

    Hi Neil,
    Thanks, sounds like a good solution which I never thought of myself.
    The only thing is I wanted the whole thing to be 'autonomous', so that
    it comes on and switches itself off after 30 seconds at a pre-defined
    time each day... which the buzzer in my organizer does. Is there a
    low wattage consuming microphone on the market to your knowledge that
    could do the trick?
    Thanks, again.
  4. I'm thinking you could probably figure out how to slap something together
    that would operate on a couple AA batteries. You'd place the organizer near
    the sensing microphone, and when it's alarm goes off, it would trigger the
    relay in the sensing apparatus. What do you really want to do? Turn a
    light on-and-off or something?
  5. Abdul Ahad

    Abdul Ahad Guest

    I wanted to use the output from the orgainser to switch on a small
    motor which will drive a fan to dispense fish flakes into a pond as
    automatic fish feeder! Its the microphone & relay specifications that
    I need to know. What specifications can they be for 2 AA batteries? I
    can then buy them in Maplins.
    Abdul Ahad
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