RF activated relay

Discussion in 'General Electronics Chat' started by hazim, Dec 1, 2009.

  1. hazim

    Thread Starter Active Member

    Jan 3, 2008
    I googled a lot for a schematic of a RF activated relay and I didn't find any. The circuit I need is made up of two parts, the RF transmitter and the receiver.
    What I exactly want is a circuit similar to the one in this link http://www.aaroncake.net/CIRCUITS/irremote.asp , which does what the circuit in the link does but using Rf instead of IR.
    I'd like to build it myself, but my experience is still not enough to build such circuits..

  2. SgtWookie


    Jul 17, 2007
    IR receivers are prone to interference, just like Aaron Cake mentioned.

    RF receivers get blasted with a broad range of frequencies. A receiver would have to have high sensitivity, selectivity, and then might still be activated by another transmitter.

    To prevent unintended activation, you really need a receiver that has a rolling code in it.

    Googling "Rolling code kit" or "rolling code receiver" will give you a lot of results.

    Senior Member

    May 26, 2009
    When operating my HF radio equipment, and when I transmit a full 100W of power, I've noticed that other analog power meters go up to indicate that power is being transmitted; even though it's not directly connected to my transceiver. Thus, you could possibly get an analog power meter (small and inexpensive one) so when RF is situated near it the coil inside will receive the energy and move the needle. Then, using a motion sensor to detect when that needle moves and then indicate it accordingly. You might have to change the value of the coil in order to get better sensitivity, but it's just an idea.

  4. hazim

    Thread Starter Active Member

    Jan 3, 2008
    After I saw what is available on the net.... definitely not as I need it (neither the simplicity nor the function), I'll make my own one in my closer vacation and which it will be very simple and practical....