Page 29 - 2015-12
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The  machine                        The  school  wanted  three  different  TV  sets
        was   enor-                         converted  to  connect  to  the  VTRs,  as  well,
        mous, it used                       they wanted provision to be able to record the
        two inch wide                       off-air programs from the TV.
        tape  on  large
        reels,  which                       There was no way this could be done on the
        seemed to run                       spot, as it required a considerable amount of
        through  at  a                      work. I took a VTR and one of the class room
        very   high                         TVs to my workshop,  where I started on the
        speed (actual-                      design of an interface between the VTR and
        ly  it  was  15                     the TV.
                    Ampex 2” VTR (source: Internet)
        inches   per
        second).  The  black  and  white  image  on  the  This took quite a bit of designing, with a lot of
        monitor looked pretty good (by the standards  cut and try involved. The audio was of course
        of the day).  This was an Ampex quad video  no problem, but the video presented a greater
        tape recorder (VTR). The word quad referring  challenge.  How to connect the low impedance
        to the four video heads which scanned the tape  in/out of the VTR to the high impedance of the
        in a transverse (width-wise) direction.  video circuitry of the (valve) TV - bearing in
                                            mind the TV still had to be usable for normal
        Now moving  forward to around 1970, I had  TV viewing.
        started my own business by then. I received a
        call  from  a  well-known  school  here  in
        Geelong, they had just bought three video
        tape recorders, but could not connect them
        to their class room TV sets, could I come
        and  sort  it  out  for  them.  Well,  always
        being interested in new stuff, the answer
        was  pretty  obvious.  On  arrival,  I  was
        shown one of the machines - it was a Sony
        reel-to-reel VTR. The video/audio output
        was odd looking squarish multi pin con-
        nector. Only video/audio in and out. No
        internal  tuner  for  recording  off-air  TV
        programs.  At  that  time,  no  TV  on  the
        Australian market had provision for direct
        connection of video/audio -in fact the only
        connector on the TV was for the antenna.   Sanyo Reel to Reel VTR
        Below: Sony CV-2000 VTR  (source: Internet)
                                            The eventual design was a four transistor ar-
                                            rangement  on  a  small  circuit  board,  which
                                            could be fitted anywhere in the TV that space
                                            would allow.
                                            All three class room TVs were converted and
                                            worked quite well,  the school must have been
                                            happy with the job, as within a few weeks, I
                                            had two other schools wanting the same job
                                            done, they had bought the same VTRs.



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