Cordless phone detector.

Discussion in 'Wireless & RF Design' started by nerdegutta, Oct 30, 2011.

  1. nerdegutta

    Thread Starter Moderator

    Dec 15, 2009

    Which of these circuits would be best for detecting a cordless phone ringing?

    The phones are Siemens Gigaset, I think... It's at my parents house.

    I only need a circuit to detect the RF signal, the LED bit I hope I can manage to put in myself.
    The volume on the cordless phone is not high enough, so I thought some flashing LEDs or something would draw the attention to the phone.

    Also, I guess it is not recommended to breadboard this type of circuit for testing, due to all the stray capacitance and long legged components...

    I've googled and youtubed a lot, and these circuits gets hit all the time.
  2. radiohead

    Distinguished Member

    May 28, 2009
    On the first circuit, do you have a component list? The IC is probably a 555.

    The second circuit looks simple enough to breadboard, just to see roughly how it will perform.

    The third circuit uses an op amp to amplify a weak signal and feed it to a 555 that drives an audio indicator. If all you require is a visual indication, you can omit the entire 555 circuit (C7 and everything to the right, except for the battery and switch).

    If you want to build a prototype and don't want to breadboard it, you can use the dead bug (air circuit) or Manhattan style of circuit construction.
  3. nerdegutta

    Thread Starter Moderator

    Dec 15, 2009
    Yes it's a 555

    Tried it, but it didn't do anything. :(

    I only need visual indication. So this I might try.

    Now why didn't I think of that! :rolleyes:

    But which of them would be best?
  4. bertus


    Apr 5, 2008

    The circuits you show do not have a real RF detector in them.
    The transistor or IC are supposed to perform the function.

    The circuits on this page do have detection diodes in them: