multiple frequency transmitter

[chinsoon]

I have a project, for me to control multiple electrical appliances at the same time, wirelessly.

so i am thinking of having a transmitter circuit, which will actually transmit the on off commands (signal) with different carrier frequency, so that each frequency will corespond to only one receiver.

I am thinking of using ASK since the input of this transmitter will be logic levels 1 and 0 ( 5V and 0V).

can anyone provide me the link for the circuit diagram of such device that can send out signal with multiple carrier frequency, or even if you have a better suggestion.

thank you.

 

[Nigel Goodwin]

You don't need multiple frequencies, each receiver should have it's own unique ID (basically a number), the transmitter sends out both an ID number and a command, all receivers listen to each transmission, but only act on ones that use their unique ID. To send to all receivers, simply adress each receiver in turn.

It's how everything remote control in your house works!, and why your TV remote doesn't affect your VCR or stereo.

Check my PIC tutorials for examples of IR and radio transmissions.

 

[Hero999]

One way is to use a touch tone encoder on a basic audio transmitter and decoder on a reciever. This will give you the ability to control four different devices simultaniously or 16 different devices independantly.