I found a circuit to do exactly what I wanted here:

http://www3.telus.net/chemelec/Projects/Timer/Timer.htm


Here is an example circuit of the above:

http://www3.telus.net/chemelec/Projects/Timer/Timer-1.jpg


I'll let you know how it goes ;)

Cheers, Graham



--- In CasioSK@yahoogroups.com, "gmeredith1" <gmeredith1@...> wrote:
>
> That's the sort of circuit I had in mind when I was toying with the
> idea. Does anyone know what value components you need to use with a
> 555 to get it to pulse once every 5 mins, but with a short "on" time?
>
> Cheers, Graham
>
> --- In CasioSK@yahoogroups.com, "Mark Rauch" <billbigrig@> wrote:
> >
> > Howdy,
> >
> > Couldn't a guy put a 555 timer in there and have it trigger a non-
> > sound event every 3 or 4 minutes to keep things powered up? It
could
> > be switched off when APO is desired.
> > Rig
> >
>