Hello everyone.

Sorry to be a pain but, in spite of Bg's efforts to put some photo's
in the group files, I'm having trouble getting my head around it
all. I want to be able to flip the polarity of various voltages,
(all low..) and a simple miniature relay change-over timer circuit
would enable me to do this, rather than what I see featured in the
files.
I need to find a simple schematic using a 555 timer chip which will
do this.
The 555 switches on for a while then switches off for a while I
understand the 555 won't flip polarity on it's own, hence the relay -
A minature Double pole changeover relay, driven by the timer WILL do
this.

I've looked at various sites featuring the 555 timer but can't quite
get my head around the various terminology and can't see a simple
enough circuit.

Can anyone give me a hand on this?

This seems really fundamental to group experiments in this area and
I'm sure that there will be others wanting something similar.

Having a relay there with totally independent contacts means that one
can use any voltage and not rely on the timer chip circuit.

Cheers.

Ed