Sanjeev Wrote --->
perhaps you are also right the cheapest way to transmit tone over a wireless is
555 timer as a fsk generator and 565 as fsk demodulator it works well and fine opt for them do remember to add rc ladder filter and an opamp at the out put ofcourse opamp working at TTl :-) .
hope this info will help you
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Cory Spackman ----->
Remember, you get what you pay for. I think that many RF purists would
cringe in pain when presented with an FSK system based on 555 timers. I prefer crystal controlled frequency references.
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Hi All,
OK you want crystal controlled FSK then how about a 32,568 Hz crystal hooked up to a 4060. Feed 1024 and 512 Hz into a 4001 with EIA control to a digital RF (433 mhz) transmitter for the send side. Then use a digital RF receiver and sent that into a 4046 Phase lock loop to demodulate the FSK and you make everybody happy. Total cost is less than $15.00 per unit.

Regards,
Charles Bannister