Hi,
There are cat finder units available, but the various cat type forums
don't rate them much.
The audio type of thing reminded me of a tale about a bloke who lost
his watch in the dark, in long grass.
Back home he remembered that it was set to alarm daily, and he went
back to find it when the alarm went off. He got his watch back.
I dunno, i don't fancy having the cat bleeping anyway, i would
want the unit to be small enough that it won't bother the cat,
and also i would like it made so that it only sends an RF beep upon
a signal from 'home'.
I reckon a transmitter could be made really small and run from a tiny
battery cell. If it were dormant most of the time, then maybe it could
last a very long time.
Such a project has intrigued me for a long time now,
I would be interested in any ideas or suggestions.
John