Or Infra Red LED / Receiver
If you drill a hole through the frame sufficient for an IR led, this would be possibly better since you might have difficulties with persons who like to jam or interfere with RF frequencies especially 455 MHZ
In conjunction with this you don’t have to worry about the DTI complaining that you are interfering with other radio frequencies
There are of course the remote IC’s supplied by Maplin,s which give five channel decoding ,encoding ,with which you can use Infra red diodes pickups with slight alteration to the circuit
Or alternatively use the Phillips or Sony IR code and program a suitable PIC cpu to do the job of infra red / TX – RX
Or you could use very plain and simple RS232 protocol asynch to drive the led with another processore ready and waiting to recieve
You could further enhance this and produce a readily available attachment to a mobile phone which notifies you in the garden or elsewhere on your mobile phone to let you know someone is at the door by sending you an SMS
OR if you really fancy produce software with suitable attachment to the PC which automatically networks your bell message to a selection or receivers of your choice
One step further utilise bluetooth modules providing serial over bluetooth protocol or just simply IRDA
Finally if your bell is in a different room of a hallway or similar then you could add a simple TV remote extender which is essentially a repeater
There a stack of ideas for you to enhance on
All would work and very well they would too
Mark
www.harrington.force9.co.uk