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Teletype etc (was RK05)

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  • David Gesswein
    ... Thanks ... I was recently looking at that and either missed it or didn t see the schematic for the 4915 board. I did find a version here
    Message 1 of 6 , Dec 30, 2012
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      On Sun, Dec 30, 2012 at 02:31:11PM -0500, B. Degnan wrote:
      >
      > By the way, thanks for the great web site, I really appreciate the
      > time and effort put into putting all this together.
      >
      Thanks

      > I am getting closer to having a
      > "DEC teletype" set up, by following these directions
      > http://www.pdp8online.com/pdp8cgi/query_docs/tifftopdf.pl/CHD/LT33_print_set
      > .pdf
      >
      I was recently looking at that and either missed it or didn't see the
      schematic for the 4915 board.

      I did find a version here
      http://so-much-stuff.com/pdp8/cad/boards.php
      The free version of Eagle will dispaly them. I put a PDF copy here in
      case you don't wish to download Eagle.

      http://www.pdp8online.com/ftp/misc/4915/

      I was reparing some of my spare cards and noticed that the reader run
      drive signal was going way negative at turnoff. When I originally did it
      many years ago I didn't put a diode across the relay coil. Adding that
      made it stop abusing the drive transistor.

      > Right now my teletype is stock, and only capable of receiving, but at least
      > that part works great now.
      >
      Thats good. Hopefully you will have it fully functional. It should
      transmit without the mod, just the paper tape reader may loose characters
      and won't turn on automatically.

      Those bus bars they used on cards for power distribution are annoying
      me. One card had an intermittent where one of the pins has bad solder
      joint. Another card several of the pins were broken off entirly that
      was a pain to fix.
    • Dave McGuire
      ... Seconded! It s great stuff. In fact when I first met you in person at VCF-E in 2011, I felt a bit of celebrity shock . :) -Dave -- Dave McGuire, AK4HZ
      Message 2 of 6 , Dec 30, 2012
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        On 12/30/2012 04:15 PM, David Gesswein wrote:
        >> By the way, thanks for the great web site, I really appreciate the
        >> time and effort put into putting all this together.
        >>
        > Thanks

        Seconded! It's great stuff. In fact when I first met you in person
        at VCF-E in 2011, I felt a bit of "celebrity shock". :)

        -Dave

        --
        Dave McGuire, AK4HZ
        New Kensington, PA
      • David Gesswein
        ... This may have been unclear. It is referring to the reader run mod. Teletypes had lots of options so it can be configured such that it doesn t work. The
        Message 3 of 6 , Dec 30, 2012
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          On Sun, Dec 30, 2012 at 04:15:19PM -0500, David Gesswein wrote:
          > It should
          > transmit without the mod, just the paper tape reader may loose characters
          > and won't turn on automatically.
          >
          This may have been unclear. It is referring to the reader run mod. Teletypes
          had lots of options so it can be configured such that it doesn't work. The
          teletype does need to be set to passive transmit loop (just contact closure).
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