[GreenKeys] How The Teleprinter Works- 1940 (11:05 mins)

[Sam Hallas]

COURYHOUSE at aol.com wrote:
> just  to clarify... single current  working is like  comes out of the
> back of HAL st-5000  tu?

I wouldn't know what comes out of an ST5, Ed.

By single current, I meant on/ off keying. Double current meant 
positive/ negative current.

I think the terms go back to Morse telegraphy on long cables. Double 
current was used on undersea cables with a mirror galvanometer to detect 
the signals at the far end.

Does that clarify it?

Cheers,
Sam