[GreenKeys] Polar Loop wiring?

[Sam Hallas]

jhhaynes at earthlink.net wrote:
> If there is more than one sending machine then you don't have a polar
> loop.  A polar loop works fine where there is one sending machine and
> lots of receive-only sets - you just wire them all in series.  But
> when there is more than one sending machine it gets complicated.

Thanks, Jim for the detailed explanation. There's a diagram of how polar 
loops work on my web site about single needle telegraphs. The principle 
is the same. Current reversal are signalled by multiple stations in 
series. The battery is not earthed in this case, but the principle is 
the same.
http://www.samhallas.co.uk/railway/single_needle.htm

Cheers,
Sam