to quote radioron
"However, in addition, it might be wise to send a simple tone over the radio and then use a tone decoder on the receiver. It would be easy to interface the encoder to the transmit unit microphone and the decoder to the receive unit speaker. The output of the tone decoder would be your switch driver. The old standard tone encoders and decoders are the LM566 and LM567 but there may be newer and better chips now. Perhaps try Maxim."

what is maxim, how would i build this and can some one please send me schematics for a simple encoder/decoder hook up. i have done some searchs on the web but not have turned up anything of much use please help

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ehhhh?!

 

Maxim is this manufacturer:
http://www.maxim-ic.com/
Also Google for CTCSS decoder. Most newer ones use a micro, but here is a schematic of an analog one:
http://www.norcommcorp.com/pub/manuals/NC102-00.PDF
You could also use the LM566 and LM567 instead as mentioned by RadioRon.

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--- The days of the digital watch are numbered. ---

 

A single tone is not suitable to switch something when it is transmitted by radio because noise, music and voices can trigger the very simple decoder.
Telephones have used touch-tone (dual tone multi frequency) for ages to avoid such problems.

In the 80's touch-tone encoder and decoder ICs were available.

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Uncle $crooge