[GreenKeys] Mystery RTTY Project

[Harold Hallikainen]

That IS pretty clever! I assume the printer has auto CRLF since the
generator would only generate RY. Also, all bits would be the same length,
including the stop bit which, for 60 wpm is usually 31 ms long compared to
22 ms for the other bits. But, if we are sampling in the middle of the
bit, it seems like any stop bit longer than 11 ms would work. Thinking
about the square wave, I get

0 - start
1 - D0
0 - D1
1 - D2
0 - D3
1 - D4
0 - stop

So, it seems like we'd get framing errors on a square wave since the stop
bit is a 0.

Harold
https://w6iwi.org

On Sat, July 8, 2023 3:41 pm, Skip Macaulay wrote:
> Wild project, real bread " board" stuff !!
> Skip
>
> Skip MacAulay
> VE6BGT
>
> On Sat, Jul 8, 2023, 4:20 PM B. Smith, <smithab11 at comcast.net> wrote:
>
>> Several have figured out the project. The RY's are generated by sending
>> a square wave using a 555. The 555 then drives an HSR series optical
>> switch which keys the local loop. Dovetron does a similar operation with
>> their RY generator. There are plenty of Chink 555 boards on ePay that
>> are all ready built and cost is around 2 bucks.
>> Photo Attached.
>> K4CHE
>> http://k4che.com/Tempvideo/RTTY%20Mystery%20Project/Mystery%20K4CHE.mp4
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