Key ringer

Discussion in 'General Electronics Chat' started by vimal333, Apr 19, 2012.

  1. vimal333

    Thread Starter New Member

    Nov 10, 2011
    I'm trying to built a key ringer (which can be attached to the key as key chain so that it can be easily found out with the help of the beep sound when misplaced). I know its available in the market but wanted to make one of my own.i figured it out that it should have a RF transmitter receiver with a beeper attached tot he receiver ,but dunno really where to start. This is the one I'm talking about .Saw many circuits like whistle key finder etc but this the one i really want to make.:)
  2. MrChips


    Oct 2, 2009
    Yeh, but how do you find the key ringer when you lose it?
  3. DenisM

    New Member

    Apr 23, 2012
    I remember seeing those years ago. They were not activated by a remote. You would only lose the remote anyway :(

    They were activated by clapping your hands - making some noise - and the device would respond by chirping.

    So I reckon you need a device with a small microphone and a small speaker. It would have to come on only in response to a sudden sharp sound, otherwise it's battery would run down with ambient noise.

    No remote control device would make sense.

    Good luck :)
    Last edited: Apr 24, 2012
  4. DenisM

    New Member

    Apr 23, 2012
    Hey! I've just read the full site you referred to

    and it does seem a sensible solution. Each device can find another. So you keep one of them safe always - as suggested - stuck to your fridge.

    Still - the temptation to walk about with the 'safe' one when something is lost, would inevitably lewad to its loss also :(

    It's easier to make a whistle or clap as neded

  5. praondevou

    AAC Fanatic!

    Jul 9, 2011
    Unless you want to build an RF receiver/transmitter from scratch I recommend low power RF ICs from Micrel or Linx Technologies.
    There are several different types available.


    Your major obstacle is battery capacity. There exist "long" range passive transponders but that's a much more complicated project.

    The above mentioned low power UHF receivers need to be used in polled operation, in order to save current.