RF transmitter/receiver system

[ahmed1313]

Hi all,

  I'd like to design an RF transmitter receiver system that can control say 8 relays.
I found something on the net that I want to build myself in the following site:

http://www.apogeekits.com/rf_remote_control_set.htm

Some people told me about some transmitter/encoder IC's like
HT12E and one built in LINX KH RXD

http://www.linxtechnologies.com/Products/RF-Modules

What is the theory of operation of these encoders?

I'd like someone to explain very briefly the theory of operation and the tranmission type of this digital data and modulation types too ... and if you can refer me to more resources.

I haven't read about digital communications for a long time.
Just mention very brief description or topics names and I can find myself more explanations.

Do these encoders use ASK (Amplitude Shift Keying)?

Also, someone told me to use DTMF circuits. Can I get the same results using these circuits and what are the differences?

And I think I can control 2^8 devices through these circuits if I used DECODERS in the receiver circuit, right?

Thank you very much :)

[ahmed1313]

Where are you guys?????????????????
[move]Where are you?[/move]

[Um...Me123]

I used an old RC car circuits to control 4 relays so your beyond me.  It was a forward-backward type car that switched the polarity for two motors with two mom. center off switches.  Use some diodes to split those 4 wires to 8 and you got yourself 4 relays.  I know this was no help but I feel like typing ::) 

[ahmed1313]

Thanks me123

No one else wants to help?