"John Fields" wrote in message
...
---
Thinking about it a little bit more, if you were to replace the
fixed 1 megohm timing resistor with a pot and you adjusted it to
make the first five minute timing interval accurate, then all of the
other intervals would also be closer to what you're looking for.

--
John Fields
Professional Circuit Designer

I have ultimate admiration for anyone who can come up with something like
that on the spare of the moment. Personally I'd take the 'easy' route and go
with a www.picaxe.co.uk picaxe micropro - so easy to use its untrue. I was
introduced to them by someone on here too.

J