Other uses for old TVs

I started this thread to see if anyone else has used old televisions for other interesting projects, other than wine cabinets, that they would like to admit to on this site.

I was finishing high school in the late 60's when I recaped my first set. It was an Admiral with a 19 inch round metal tube. Shortly thereafter, I decided to play around with the idea of using it to display audio signals. After much experimenting I ended up with something I called my Psychoscope. The Psychoscope was a box that contained audio amplifiers that could drive the deflection yoke of the TV with audio signals. One channel was fed to the vertical, and the other channel was phase-shifted with a resonant tank tuned to bass frequencies common to most rock and pop recordings, and fed to the horizontal. The vertical and horizontal amplifiers were push-pull 6L6 transformer-coupled designs, and coupled to the yoke using the 16-ohm secondaries. Since the yoke was an inductive load and fed with what was more or less a voltage source, the low frequencies resulted in the most deflection on the CRT.

The display on the TV using the audio as the deflection in this way resulted in a toy that was a real blast. I even sold a bunch of these in the early 70's. With rock music, you would get pulsing circles and cardioids that would explode and spin around to the music. For classical music, you could switch out the phase shifter and get exploding squiggly patterns. I also added several internal oscillators to the Psychoscope that could be used to apply video signals and additional deflection signals that could be mixed with the audio. With the video, you could get exploding star-burst patterns or dashed lines. The oscillator-audio mix produced other patterns that were too weird to describe. Because all of the light output from the CRT that is normally spread out over the whole screen via the raster pattern was now concentrated into thin lines, these lines were extremely bright and vivid. With only one exception, I made all of these using B&W sets. The lines were so vivid, though, in a dark room most people would start seeing colors after a short time. Actually, the color on occasion was real; as if the high-intensity beam was allowed to shrink to a small dot it would quickly burn the phosphor with an orange flash. On the color one I made, I designed auto-brightness circuits to prevent this from happening.

Magnetic deflection TVs of this era needed the deflection yoke for energy storage for the flyback pulse that was used to provide high voltage for the CRT. Because I was using the yoke for audio deflection, I mounted a second deflection yoke somewhere in the TV cabinet so that the inductance from the winding could be used in the flyback-based high-voltage circuit. On many of the sets that I converted for use with the Psychoscope, I included means to switch back and forth between Psychoscope use and TV use.

I might even be able to dig up the schematic for the Psychoscope if anyone is interested in seeing it posted.

I remember seeing an ad for a kit that converted a b&w tv into a large screen oscilloscope.

[Eric H]

Don't anybody say Fishtank

[Rob]

David,

That sounds like a very nifty display idea! I did something similar to a 14" B&W Sparton chassis that I had when I was in grade 8. I rotated the yoke on the CRT so that the vertical sawtooth became the horizontal timebase. I mounted an outboard yoke to satisfy the requirement of the horizontal output circuit to have an inductor to still operate and provide HV for the CRT, and used the newly disconnected horizontal windings of the yoke on the CRT to provide vertical sweep. I used the loudspeaker pre-amp as the vertical deflection amplifier (6AV6?) and ran an input jack to the high side of the set's volume control, disconnecting the feed from the FM detector. The output of the audio transformer was disconnected from the speaker and hooked to the H. windings of the yoke. Voila... big screen audio oscilloscope! You sure are right about the trace being bright! I never did burn any phosphor though. I was playing guitar in a garage band at the time (also built my own tube guitar amp, P-P 6L6's) and we used my o-scope on the set when we were playing as a visual effect along with our home-made rotating disc stobelight.

I had ideas about doing along the same lines with a color TV chassis and having a whole bank of 6SN7 based multivibrators (which I was fascinated with at the time and breadboarding) as pattern generators to mix into the input and brightness circuits, but never got beyond the drawing stage. It was impossible for me to come up with a color TV chassis at that time of my life 1968'ish. People were buying their first color TV's in my Vancouver neighborhood in 1968, not throwing them away. Canada went to limited color broadcasting (testing) in 1966 and some networks, notably the CBC adopted it in 1967.

Rob

[radiotron]

Originally Posted by Eric H

Don't anybody say Fishtank

PLEASE DONT OR ELSE:

[crtfool]

F...i...s...

[stromberg6]

Originally Posted by eric h

don't anybody say fishtank :d

nfw!!!!!

[Eric H]

Talk about bringing a thread back from the dead, this ones ten years old!

[radiotron]

Originally Posted by crtfool

F...i...s...

Thank you
ME= fish what?
fish t...=
after=(police right next to me) Did I do that?

[zenithfan1]

Wow, I was just out of high school when this thread was made......
EDIT: Oh crap, almost forgot.

[snelson903]

been getting kinda wild in here lately,esp with banana's

[josephdaniel]

I was four or five when this thread was started!!!

[zenithfan1]

Yeah, so wild that they have stopped working it seems. LOL! I see them all standing still, do you? I think we killed them! YAY!!!!!
Josephdaniel.....SHOWOFF!

[Eric H]

Bunch of young punk Whippersnappers!

[radiotron]

Originally Posted by snelson903

been getting kinda wild in here lately,esp with banana's

I see your 2 bananas, and raise you 2 more