[sdiy] cool TV/oscilloscope hack..

[Scott Gravenhorst]

"Paul Maddox" <P.Maddox at signal.QinetiQ.com> wrote:
>Jay,
>
>> in my opinion, there's just not enough oscilloscopes in synthesizers.
>> maybe this can fix that:
>>
>> http://www.censtron.com/avu/
>
>I did something like this a while back, its quite simple.
>
>- Get a TV,
>- Get an old PA
>- open the TV and diconnect the coils from the PCB (one 4 prong connector
>usually).
>- meter the wires and find which are the two sets of coils (somewhere
>between 4 and 8 ohms normally)
>- Connect the speaker out of your PA to these pairs of coils.
>- apply you signals to the input of your PA, switch on the TV and you're
>done!

I did this too in the days of black and white TV, the one step you missed
is that (at least for my TV) the high voltage is produce as a product of
the horizontal sweep oscillator and amplifier.  This system required the
horizontal yoke coil to operate both sweep and generate high voltage for
the CRT.  So I found another compatible yoke coil, bolted it to the side
of the TV, wired that into the horizontal circuit and high voltage was
produced.  Then using 2 amplifiers, one for X, one for Y and you have a
Lissajou figure display.

It was cool as in better than no oscope at all, but very crappy.


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