XPost: alt.folklore.computers   
   From: g4ugm@dave.invalid   
      
   On 14/11/2024 22:29, Lawrence D'Oliveiro wrote:   
   > On Thu, 14 Nov 2024 22:19:48 +0000, Sn!pe wrote:   
   >   
   >> Lawrence D'Oliveiro  wrote:   
   >>   
   >>> On Thu, 14 Nov 2024 18:45:48 GMT, Charlie Gibbs wrote:   
   >>>   
   >>>> Original Teletype machines ran at 45.45 baud.   
   >>>   
   >>> I remember labels on Creed machines saying "50Bd".   
   >>   
   >> I had a Creed 7B 60 years ago, I used it for RTTY.  It had two   
   >> governers, one for 45.45 Bd, the other for 50Bd.  They had white strobe   
   >> marks on the circumference to set the speed accurately.   
   >   
   > Hmmm ... presumably the strobe marks were for use with a fluorescent   
   > light ... driven from AC mains frequency? Did they have different marks   
   > for 50Hz versus 60Hz mains?   
   >   
   > No, that wouldn’t work, you would need entirely different gearing for the   
   > strobe wheel ...   
      
   You used a tuning fork with a thin "slit" attached to each leg. The   
   slits were arranged so they opened and closed as the fork vibrated   
   creating a tuned shutter.   
      
   You viewed the bands on the governor through the slit and so could   
   adjust the speed and when they were stationary the spped was correct.   
   You had different forks for 45.5 and 50 baud. Some machines could do   
   75baud as well.   
      
   I found this site with some pictures and more info. There will be others...   
      
   https://www.cryptomuseum.com/telex/tools/fork/index.htm   
      
   Dave   
   G4UGM   
      
   --- SoupGate-DOS v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)