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Basic RF control transmission Answered

My goal is to press a button on my transmitter side and have the receiver flip a relay - that's all.  It's probably the simplest possible use of RF technology...  and it's almost impossible to work out on google.  I am trying to transmit and receive just a simple control signal about a range of 300m, so dismantling 27Mhz toy cars is not an option.   Has anyone successfully made a simple RF circuit before?

I can buy a 433Mhz transmitter with this range, but they take FSK or ASK modulated signals.  From what i can tell, there is nothing simpler than the 'OOK' version of ASK modulation for transmitting signals.  If I'm wrong, please correct me.  Otherwise, if I'm stuck with FSK or ASK. 

I found one site (bottom of PDF: http://www.edn.com/contents/images/101101di.pdf) providing a simple circuit to produce FSK.  I was hoping for something simpler, but if you think this is the easiest way, i'll give it a shot.

Can someone guide me towards the correct ICs and circuits to create this project?

Thanks in advance for your help



7 years ago

There should be modules readily available which are able to accept 0-5volt (or maybe 0-3.3 volt)logic levels. The ASK/FSK references should just refer to how the module modulates the RF with the data.

If you buy a transmitter and receiver pair, you should be able to put digital signal into the transmitter and read them at the output of the receiver.

Also, OOK (on/off keying) is just a special case of ASK, where the shift in amplitude is from fully on to fully off. ASK is just a more generic term.


7 years ago

Wireless remote devices capable of that range may be regulated. I think model airplane RC controllers might have that range. But it seems you only have one part of your problem solved if you build that circuit. What about the receiver and mechanism to trip the relay? Seems you need additional components and can be complicated if you deal with AM vs digital signals. Simple communications is not reliable communications. Good luck.