The problem is the RF part. It is very difficult to make RF work reliably as a distance detector. It would require something that sends out a signal which is answered by the collar and the timing measured, a simple "signal lost" will probably not work much. Radio range is a very fickle thing...
I dunno, but here we tend to attach some string to a collar to solve that problem in a very cost efficient way. Many people have leashes with a spring operated windup mechanism so the dog can move away a certain distance like you would like. The only advantage i would see is that a electronic version would no longer tangle around lampposts and other people and stuff.
Some dogs seem to be clever enough to even ride on the tube more or less independently, but others seem so chase after everything...
ST
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On Tue, 25 Apr 2006 18:26:57 +0200, fuzzzydog1 <fuzzzydog@...> wrote:
The circuit I can't design (due to lack of knowledge) is an RF
signal triggering a relay on the ultrasonic circuit stopping it from
emitting. It can't be that hard - I have seen toy radio control
cars with very small transmitters/receivers. In my example, the RF
signal would open/close the relay of the ultrasonic circuit instead
of turning the toy car's wheels...
In retrospect, i can see how the adjustable RF frequency would be
more difficult - scratch that part - it can be a fixed frequency,
preferably something that won't interfere with other people's
electronics (the range will be quite short as well so that really
shouldn't be an issue)
