Lissajous?

[gar]

190126-0715 EST

Have you ever heard of a Lissajous curve or pattern?

These are quite interesting and fun to play with.

Oscillators or function generators, and an oscilloscope are the easiest way to play. One can also make a compound pendulum to generate some ratios.

You can search the Internet and find many different presentations.

One fairly good site is https://www.youtube.com/watch?v=6WFlbHi2xnE . However, like many sites it is not professionally composed so there is too much camera motion, and lack of smooth scripting, but still good.

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[Besoeker3]

Yes, I have seen them, produced them, and played with them. Fun, but I never had a practical application for their use.

 

[retirede]

Yes, I have seen them, produced them, and played with them. Fun, but I never had a practical application for their use.

Same here.

 

[K8MHZ]

Same here.

Ditto. Played with them in the apprenticeship.

 

[gar]

190126-1005 EST

Frequency measurement. Phase angle measurement. Input vs output voltage of a transformer. Input voltage vs input current of an unloaded transformer. Then with different loads. Wind a coil on a square loop material, then plot I vs V. Make logos.

I believe my first exposure was reading about the curves for frequency measurement. But first exposure may have been high school physics and a compound pendulum. Certainly I used beat frequency to measure frequency before Lissajous because I did not have a scope. Scopes were a rare item in those days and limited in frequency range.

On beats --- https://www.khanacademy.org/science...erence-of-sound-waves-ap/e/beats-ap-physics-1

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[ggunn]

There was a band that I saw in a club back in the 70's that used them creatively.

They had a CO2 fog machine feeding a PVC pipe running across the front of the stage that had a bunch of holes drilled in it so they could drop a fog curtain in front of the band.

They had a box that held two speakers set at right angles to each other with Mylar mirrors attached to them and clear windows at each end; they put it on a stand over the drummer's head.

They set up a red laser so that its beam went in one window, bounced off both mirrors and out the other.

They set up a pair of oscillators (the old type with the large clock face on the front that controls the frequency), each one feeding a channel of a stereo amp that drove the two speakers.

Their light guy sat back at the mixer space twiddling the frequency and amplitude of the oscillators, which drew Lissajous patterns on the fog curtain in front of the band. It was pretty cool; I remember this well but I don't remember their music at all.

 

[Besoeker3]

190126-1005 EST

Frequency measurement. Phase angle measurement. Input vs output voltage of a transformer. Input voltage vs input current of an unloaded transformer. Then with different lo
ads. Wind a coil on a square loop material, then plot I vs V.
.

But would you?

 

[sameguy]

Yes back in 1975 in lab class.

 

[Besoeker3]

Yes back in 1975 in lab class.

But in real life?

 

[junkhound]

Last time I used them was in the early 60s on an old EICO kit scope, good for calibration of low frequencies on very basic equipment.

Liked the shape so much though that when I pur a new front door on the house in the 1980's incorporated the pattern in the stained glass.

 

[sameguy]

But in real life?

Well it was the 70s

 

[Besoeker3]

Well it was the 70s

I thought psychedelic was in the sixties........

 

[JoeStillman]

There was a band that I saw in a club back in the 70's that used them creatively.

They had a CO2 fog machine feeding a PVC pipe running across the front of the stage that had a bunch of holes drilled in it so they could drop a fog curtain in front of the band.

They had a box that held two speakers set at right angles to each other with Mylar mirrors attached to them and clear windows at each end; they put it on a stand over the drummer's head.

They set up a red laser so that its beam went in one window, bounced off both mirrors and out the other.

They set up a pair of oscillators (the old type with the large clock face on the front that controls the frequency), each one feeding a channel of a stereo amp that drove the two speakers.

Their light guy sat back at the mixer space twiddling the frequency and amplitude of the oscillators, which drew Lissajous patterns on the fog curtain in front of the band. It was pretty cool; I remember this well but I don't remember their music at all.

Wish I'd been there.