0
\$\begingroup\$

I've recently been playing around with analog video like composite to S-video and VCR related things like that. I've always thought it would be really cool to create some kind of analog video generator from sound.

If anyone could explain how composite video signals work and should look that would be great.

Some inspiration is from the "Atari video music" https://www.youtube.com/watch?v=BX1LVBLUYNs I also have seen people make "Dirty video mixers" which is sort of the path I want to go down.

What I haven't seen is a guitar hooked into a TV. Is it possible to convert a guitar signal into a signal that resembles RCA video? Possibly an arduino could be a good way to go? All analog would be cool though.

Thanks alot for reading.

\$\endgroup\$

1 Answer 1

Reset to default
1
\$\begingroup\$

At minimum, a guitar's signal would need to be passed through some kind of preamplifier to have any effect whatsoever on a 75-ohm composite video input. If the input was scaled to a suitable range but didn't have any sync pulses added, some analogue monitors might flash at varying intensities in response to the audio signal, but the results would probably not be very consistent or useful.

If you add horizontal sync pulses but omitting vertical, it may be possible to build a simple analogue circuit (probably 2-3 cheap chips, a couple capacitors, and a few resistors) to make an analogue TV act as a crude oscilloscope which sweeps vertically rather than horizontally. Adding vertical sync pulses would require adding another chip or two. The results would likely be rather crude, but would mirror what could have been built in the 1980s.

\$\endgroup\$
6
  • \$\begingroup\$ Awesome. Yeah I was thinking I'd be using some simple Op Amps circuit. What do you mean by cheap chips? And is there any documentation that you know of for simple composite video? Possibly simple starter circuits to play with? Thanks \$\endgroup\$
    – Cole-Peterson
    Commented Jul 15, 2017 at 0:14
  • \$\begingroup\$ The much simpler method is use an audio scope like Audacity or Audio player Visualization on the source with a PC using Aux input from Guitar preamp. \$\endgroup\$
    – D.A.S.
    Commented Jul 15, 2017 at 0:35
  • \$\begingroup\$ I could do that yeah but my goal is to build somthing \$\endgroup\$
    – Cole-Peterson
    Commented Jul 15, 2017 at 0:45
  • \$\begingroup\$ Iv'e Been looking all over for some kind of "Test pattern generator" not much has come up. \$\endgroup\$
    – Cole-Peterson
    Commented Jul 15, 2017 at 0:59
  • \$\begingroup\$ Do you have an oscilloscope handy? Your first step should be to build a 555 circuit which outputs a 15.75Khz signal with a low period of about 3.7-5.7us, and scale that to be at 0.6 volts when "high" and 0.0 volts when "low". Use 75 ohms as the bottom end of your voltage divider. A typical video input will add another 75 ohms in parallel, and thus cut the voltage to about 0.3 volts. \$\endgroup\$
    – supercat
    Commented Jul 17, 2017 at 16:02

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.