Circlescope... how is done?

[laserdelic]

I have tried to obtain this at home:

YouTube

And failed miserably. One of the axis is obviously a rotating mirror, in this case rotating exactly at some multiple of the central C note to be synced to the music, but, how it´s done the other axis?. I tried fixing a mirror to the arm of a HD, but it doesn´t produce this nice concentric effect, but an uncool horizontal distortion of the circle... What Im missing?. :thinking:

 

[Jacob32123]

I would imagine the RPM of the rotating motor has to be tuned. I would put a potentiometer on it so you can tune it.

Let us know if you figure it out, that looks cool. I would love to build one.

 

[ElektroFreak]

Seems like the beam might be moved on a horizontal or vertical axis just prior to hitting the rotating mirror. Another possibility is a mirror attached to the cone of a tiny speaker placed very close to the rotating mirror, so that the static beam from the laser bounces off the speaker mirror first, then travels a very short distance to the rotating mirror, possibly producing that effect. The speaker would be fed the signal from the music source.

If mounting the mirror on a speaker gives sloppy output, you could mount the mirror on a movable joint and attach an edge of the mirror to the speaker cone via a tiny arm (like an unrolled paper clip or something similar), so that as the speaker cone moves it moves the mirror from side to side, generating a line that varies in width with the signal applied to the speaker.

No time to draw it out, so I hope that all makes sense..

 

[laserdelic]

My set up is an arm of a HD with a fixed mirror in the axis and a rotating mirror. Doesn´t matter if the laser first hit the rotating mirror or the HD´s arm, the effect is the same: a horizontal distortion of the circle, but not the concentric effect.

I haven´t tried yet the loudspeaker version, but I guess it would be the same as the HD´s arm...

Suggestions??

 

[ElektroFreak]

Sounds like it's a timing issue, his circle would look exactly as you described yours as being if it wasn't for very precise timing of the rotating mirror's speed.