A
Allan Adler
- Jan 1, 1970
- 0
A long time ago I asked about what one would have to do to convert
a TV into an oscilloscope. I can't find my original posting on
dejanews but my recollection is that people told me one can't really
do that with a TV. I was thinking about it recently and realized that
I didn't really understand the reasons which, according to my vague
recollection, had something to do with the electron beams in oscilloscope
CRTs being controlled by magnetic fields while those in TV CRTs being
controlled by electric fields. For one thing, I'm not sure whether this
refers to a difference in the coils used or whether it refers to a difference
in the construction of the CRTs themselves.
One idea I had for converting a TV into a really lousy oscilloscope is
based on something I read once in an electronics magazine in the late
1970's and tried out (this isn't safe, e.g. once I did it and inadvertently
shorted the whole thing out with a rather large bang but no explosion):
(1) Open the back of the (b&w) TV and unplug the CRT tube.
(2) Carefully slip the yoke off the tube without cutting any wires.
(3) Take another TV and clip the wires to its yoke and remove it from
the TV. Connect its wires to another signal source, such as the
speaker wires from a record player. Then slip this coil onto the
yoke of the first tv.
(4) Plug the CRT tube from the first TV back in.
Then one turns on the first TV and the record player. When I played
Rimsky-Korsakov's Scheherazade the white dot in the center of the screen
spiraled around the screen in interesting ways.
I think that if one can do that, one can at least do some of the simpler
things one can do with an oscilloscope by building various circuits and
connecting them to the lead wires to the coil of the 2nd TV, or maybe by
programming a computer to supply signals to those leads.
Since one doesn't have any control over the circuits of the first TV,
one can't do stuff like turn the electron beam on and off, to keep
the dot from leaving a trail if one wants it to jump around to various
places on the screen.
a TV into an oscilloscope. I can't find my original posting on
dejanews but my recollection is that people told me one can't really
do that with a TV. I was thinking about it recently and realized that
I didn't really understand the reasons which, according to my vague
recollection, had something to do with the electron beams in oscilloscope
CRTs being controlled by magnetic fields while those in TV CRTs being
controlled by electric fields. For one thing, I'm not sure whether this
refers to a difference in the coils used or whether it refers to a difference
in the construction of the CRTs themselves.
One idea I had for converting a TV into a really lousy oscilloscope is
based on something I read once in an electronics magazine in the late
1970's and tried out (this isn't safe, e.g. once I did it and inadvertently
shorted the whole thing out with a rather large bang but no explosion):
(1) Open the back of the (b&w) TV and unplug the CRT tube.
(2) Carefully slip the yoke off the tube without cutting any wires.
(3) Take another TV and clip the wires to its yoke and remove it from
the TV. Connect its wires to another signal source, such as the
speaker wires from a record player. Then slip this coil onto the
yoke of the first tv.
(4) Plug the CRT tube from the first TV back in.
Then one turns on the first TV and the record player. When I played
Rimsky-Korsakov's Scheherazade the white dot in the center of the screen
spiraled around the screen in interesting ways.
I think that if one can do that, one can at least do some of the simpler
things one can do with an oscilloscope by building various circuits and
connecting them to the lead wires to the coil of the 2nd TV, or maybe by
programming a computer to supply signals to those leads.
Since one doesn't have any control over the circuits of the first TV,
one can't do stuff like turn the electron beam on and off, to keep
the dot from leaving a trail if one wants it to jump around to various
places on the screen.
