Introduction: Music Visualizer (oscilloscope)
Finalist in the
Art of Sound Contest
all thats required is:
-an old crt (almost all b&w tv's work)
-some wire tape and pliers
-a bit of wire and an amplifier of some sort
-music to run threw zed amplifier
-basic electronics knowledge is helpful
ive got about 10 reports of success which is nice
I got the idea off of this site
this is a remake of my previous instructable for the art of sound contest and just to improve it
it can operate in 2 ways depending on how its configured, a horizontal line bent into waveforms, and a dot that expands into a squiggled up circle. both in sync with the music played. just look at the pictures and video
Step 1: The TV
a B&W TV should be easy to acquire at a yardsale, thrift store,maybe in someones trash, or probably somewhere in your house. It seems like most any b&w tv will work, but i have gotten reports of color tv's working (ive tried two to no avail), also a computer monitor can work too scorcher made an instructable on it
Once you have your TV carefully open it. You should see a big glass tube with a large circuit board under it. At the end of the tube close to you will see a few wires coming out of the tube connecting to the board (leave them alone) but ahead of them you should see thick coils of wires against the tube and 4 wires coming out near these coils somehow grouped into two on each side.
be careful as capacitors on the control board can store large charges for days, and the tube acts as a high voltage capacitor in most cases not lethal but dont take chances its still potentially lethal
Step 2: Make an Incision and Hook It Up
Cut any of those 4 wires identified in the last step then turn the tv back on
if you get a vertical line then you cut one of the horizontal coils wires
as you may have guessed a horizontal line means you cut the vertical coil
make a note of which is which
*there's no polarity with any of the wires
Now what you want to do is drive one of the coils with the wires that went to the vertical coil (the vertical supply) and put music into the other coil.
The easiest and most likely to work thing to do would be to leave the vertical supply hooked up to the vertical coil and put the music into the horizontal coil.
But you could hook the vertical supply up to the horizontal coil for a longer line I think that looks better but on my newer one that didnt work. Its hard to say how much less likely this is to work statistically its got a 50/50 chance it just depends on the tv you may try it if you like
also you could hook up both coils to your sound source for a dot that expands into a squiggly circle as i said on intro i just didnt like it as much
if you use the horizontal supply you get a flat line that moves up and down with the music which is pretty dull. this happens because the horizontal supply operates at a much higher frequency and pulls the electron beam back and forth so fast that the music dosent have any time to move it before its already crossed the screen
hopefully you can strip wires solder really isent necessary you can easily twist the wires together. taping over your connections is a good idea for insulation but i didnt even do that just make sure your wires arent contacting anything when you close up your case (or when your testing it)
once you have it the way you want it run wires off of the coil(s) your putting music into so you can close back up the case any wire will do speaker wire or whatever else just put it anywhere on the edge of the case as you seal it back up and it will be held in place(picture)
Step 3: Putting in the Music
The visualizer is basically another speaker for whatever amplification your using you may not want to use your most expensive amplifier
an average stereo or a guitar amplifier should do nicely or an amplifier from some computer
*theres no polarity for this either
put the coil in series with a speaker on your system if the volume has to be way up to get the line to move decently put the coil in Parallel with the speaker
Step 4: More Info
What your basically seeing is a constant series of graphs of something like 1 to .1 milliseconds of the vibration of the music
the vertical supply pulls the beam across the screen 100 to 1000 times per second the exact frequency depends on the TV. As the beam is crossing the screen the music signal pulls it up and down effectively drawing the waveform of the audio (at 100 to 1000hz(times per second)) giving you a dynamic view of sound hopefully thats a decent explanation.
if your brave enough you could attempt to make this
and get a pretty useful scientific tool from the looks of it, too much big scary circuity for me
a few ideas(no you dont have to follow this), you could use the volume potentiometer to adjust the output, build your own driver (sawtooth) if the driver circuity on the television refuses to work as it did on a color tv i tried, with a color tv possibly use a band filter and have the wave change colors depending on the frequency (see comments). if the driver circuitry refuses to work maybe a dummy load (resistor) across the horizontal drive would solve the problem(i think that was from a comment aswell). on certain tv's you may be able to twist the plastic that the deflection coils are wound on to get a horizontal line. feel free to post your own ideas in the comments
and also have fun with your oscilloscopeish audio visualizin thing
We have a be nice policy.
Please be positive and constructive.