[GreenKeys] very cool Hell Feldfernschreiber demo

[Harold Hallikainen]

> https://youtu.be/VDB7wmV7ekA
>
> Thought you would like it. Very cool.  Radio and teleprinter condition
> superb.  I enjoyed it!
>
> 73 Eugene W2HX


That is great! I had never heard of this. Wikipedia says it was used for
newswire services into the 1980s (
https://en.wikipedia.org/wiki/Hellschreiber ). The impact printing helix
is clever. I used to work on Alden fax machines for the FAA that used a
helix drum, but they passed current through the paper to mark a pixel.
Here it's by impact. Also, the use of two helixes on the drum is clever.
You don't need any sync since lack of sync just results in vertical
displacement on the receiver, and with the text printed twice, one will
always be readable.

Something not clear to me is whether the tape advanced continuously. The
video says he had to press the keyboard keys at just the right time.

Anyway, thanks for posting the link to the video. It's a very clever
machine I'd never heard of. The printer seems pretty simple, but the
keyboard must have been a bit more complex to convert the key to an image
for the character.

Harold



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