[sdiy] Mod Wheel Thoughts

[Blandon Ray]

Just this past week I took apart one of those Morley wah pedals with
the light shutter, to turn it into a CV pedal. It turns out that
Morley made several pedals using the same circuit board, so I could
add a second LED/LDR pair and make use of an existing hole in the
shutter.

http://www.monkey.org/~blandoon/gfx/morleycv1.jpg
http://www.monkey.org/~blandoon/gfx/morleycv2.jpg

I noticed two things: first, they use red LEDs. Second, the hole in
the shutter is shaped like this (warning, bad ASCII art):

  _________
 /         \
|           |
|           |
 \___   ___/
     |  |
     |  |
     |  |
     \__/


Now, the pedal has extremely short travel, so this arrangement
probably only works where the large end of the hole is about the same
size as the sensitive portion of the CdS cell. Also, I took the easy
way out and ran the CV output directly through the LDR, but for what
it's worth, the resulting CV looks and sounds surprisingly linear.

Blandon



On Sun, 13 Mar 2005 14:26:58 -0500, mark verbos <mverbos at earthlink.net> wrote:
>  See Buchla 219 joysticks. 
>  
>  http://www.synthtech.com/pix/buchla/b219/b219_joy1.jpg
>  http://www.synthtech.com/pix/buchla/b219/b219_joy2.jpg
>  http://www.synthtech.com/pix/buchla/b219/b219_joy3.jpg
>  http://www.synthtech.com/pix/buchla/b219/b219_joy_light.jpg
>  
>  you are looking at a light bulb with 4 photo resistors around it. The stick
> is attached to a knob that goes on top of the light bulb. As you lean the
> stick from side to side it exposes the light to the opposite photocell.
>  
>  As much as Paul S. hates this design, it could be an example of a way to
> implement a mod wheel as well. With the exception that this design uses the
> light bulbs as the rotating fulcrum, which is not exactly sturdy. At least
> there are no pots to get scratchy.
>  
>  Mark
> 
>  
>  
>  harrybissell wrote: 
>  Good idea, bad implementation. Don't use reflective mode. The surface of
> your gradient will always reflect at LOT of rediation, even when its black.
> Put the cell on either side of the wheel, and use a halftone pattern or just
> an eccentric cut on the bottom of the mod wheel, so that the shadow of the
> wheel shades the cell. Another solution would be a fabric 'shade' like
> Morley used in their optical guitar pedals. The rotary motion of the wheel
> could operate a little window shade between the light and the cell. The mod
> wheel will be able to respond quickly in the direction of more light (lower
> resistance) but more slowly in the other direction H^) harry Ray Wilson
> wrote: 
>  Hi All I would like to seed a discussion about mod wheels using LED and CS
> cell. Check this out and tell me how this might work... or not.
> http://www.musicfromouterspace.com/analogsynth/ModulationWheel/ModulationWheel.html
> Thanks Ray