Joe Koberg wrote:
> These guys did a bit of hacking inside the monitor to allow it to
> serve as an analog waveform (not raster) scope.

I didn't look at the link, but I did something like that in college 35 year=
s
ago.  One of my friends had a old black and white TV with a busted tuner.
He also had a neon sign transformer we used to make the high voltage.  That
left the deflection coils all to us.  I rigged up a sawtooth generator and
driver for the horizontal coil and we used a regular audio amp to drive the
vertical coil.  We never set up any trigger circuit, but it was still fun t=
o
see the waveforms on a really big screen.

Then we drove the horizontal and vertical coils from my roomate's stereo.
You could switch the amp to mono, and you got mostly a diagonal line as you
would expect.  Switching it to stereo you saw interesting displays.  I
remember that one particular John Denver song (I think it was "Calypso")
displayed nearly a circle when he sang a long note.  The left and right
pickups must have gotten the note just right at 90 degrees out of phase wit=
h
each other.

It was fun to mess around with, but making a real oscilloscope out of it
would have been a lot more work with not great results.  Due to the
inductance of the coils, it would have been limited to the audio range.  We
did this just for fun, and of course learned a bunch in the process.  We ma=
y
have created the first mindless automatically generated visually interestin=
g
display to accompany music.  It was better than what Windows Media Player
shows today.

By the way, the guy who's TV it was and I think had the original idea may b=
e
known to some of you as "Crash" on the Nerds Junkyard Wars team of a few
years back.  The TV oscilloscope thing was when we were both sophomores at
RPI.


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