This is brilliant

[culturejam]

The trick here is to use a small PC fan like midway implied.

Yeah, I bet the fan will put out less noise than a full-on motor. And you could actually clip the blades off and use the velcro/disc set up.

[madbean]

I think it could be made to sound quite good with the right circuitry. Just hooking up a photocell b/w in and out does not cut it for d00dz like us. The fan thing might allow for some speeds not attainable by LFO. Then again, I guess it will vary a lot on the actual photocell used.

[atreidesheir]

Why couldn't this be implemented in to a leslie sim.  Use the tremolo for the bottom speaker simulator and a second one with something blocking portions of the light detectors for the horn simuator.  You only block portions of the detector to simulate the doppler effect of the horn.  Or you could place the led on a horizontal fan blade to simuate the rotating horn and adjust the volume of the different photo detectors around the fan to simulate the doppler sound.

Am I making any senes?

[JakeFuzz]

Why couldn't this be implemented in to a leslie sim.  Use the tremolo for the bottom speaker simulator and a second one with something blocking portions of the light detectors for the horn simuator.  You only block portions of the detector to simulate the doppler effect of the horn.  Or you could place the led on a horizontal fan blade to simuate the rotating horn and adjust the volume of the different photo detectors around the fan to simulate the doppler sound.

Am I making any senes?

The doppler shift effect is from the velocity summation of a moving object emitting sound. You are adding (or subtracting) the velocity of sound to the velocity of the object relative to the observer. The change in velocity causes an apparent change in wavelength which results in a slight (think of the ratio of the speed of sound to the velocity of a leslie speaker) change in frequency (pitch). Putting the LED on the fan wont cause a shift in the sounds frequency. If you could put a speaker on a rotating fan that would work but then we are back to the leslie concept. 

[night-B]

Why not placing a small disc cutted of an old vinyl record with holes made with a paper punch, and place it instead of the wings of the fan 

[aballen]

Very cool, I love the idea of moving parts on my pedal controlling the effect... but this pedal does seem fragile and I'm already pretty fond of my modded EA trem.

A a proof of concept this this is awesome though, I can wait to see what you guys come up with.

[jkokura]

I think I agree - if this is going to be an occasional effect, only for showmanship really, I'd rather have the spinning element visually available, outside the enclosure.

Hearing that record idea, I wonder if it's feasible to take one of those old school, battery operated, kids record players. The ones that used to operate with a plastic disc? Repurpose the whole enclosure, then you don't even need to work about the motor for spinning or the material for spinning discs. Then we just need to find a way to fill the circuitry into the equation.

Jacob

[night-B]

I wonder what it would do to control the gain of an OD with that device instead of a pot, think it would give a sort of grainy tremolo at high speed 

[culturejam]

Why couldn't this be implemented in to a leslie sim. 

Yes. And the ramp up / down could be footswitchable. 

[atreidesheir]

I was thinking surround the fan mounted led with a piece of plastic  with ascending and decending circle cutouts to allow differing amounts of light to reach a detector surround array, slightly mimicing a rotating speaker effect [probably more doppleresque in conjunction with a vibrato for frequency modulation).  
A cutout similar to this:
I explained an effect idea using crop circles.   I could call it the aluminum hat.
 

[night-B]

Thinking of putting the ldr/led/fan system in a separate enclosure and connecting it to a stompbox via an expression jack ...

[jubal81]

This might be a good use for those hard drive motor hacks. There are plenty of tutorials and circuits out there for that.
If you go to the youtube page for this video, he has a link to the schematic and instructions.