Wireless Transmitter and reciever

Hi,

I've got a friend who lives on a farm and is wanting me to make 3 wireless relay switches that can work up to 500 meters. Can anyone tell me how to go about it so that their frequencies don't get muddled up? I also need them able to change around the transmitter they receive from (or vice-vesa).

Also, can someone please tell me what is legal and what isn't with wireless devices?

Any circuit diagrams would be appreciated.

Thanks
jameske

What's legal depends where you are - and you haven't filled your location in!.

But most countries have licence free radio modules, and you should use those, rather than make your own.

Sorry, I come from Victoria, Australia about four hours from Melbourne. you wouldn't happen to know what the rules and regulations are here would you?

And do you know any websites I can get onto for these radio modules?

Thanks
jameske

Licence-Free Data Radios - RF Innovations Wireless Data Australia

Australia and NZ are fairly free (have more licence free freq's then the rest of us around the globe)... but local shops are sure to know what is "locally licence free"

jameske said:

Sorry, I come from Victoria, Australia about four hours from Melbourne. you wouldn't happen to know what the rules and regulations are here would you?

And do you know any websites I can get onto for these radio modules?

Thanks
jameske

Click to expand...

Have a look here :
Radiometrix uk radio modules low power radio module miniature radio modules uk

I found these modules on this website. Do you think they would work?
(A transmitter as on the bottom of these pages would be added)

Oatley Electronics

or

Oatley Electronics.

Thanks,
Jameske