[Re: Hall effect CV pedals (was: Volume pedals for CV discussion)]

[Harry Bissell]

Harry Bissell writes: I'll bet if they were making a awh out of it, it
probably wasn't a hall effect device. Old Maestro and Cry-baby wahs used a
fixed inductor and a tuned circuit using a pot. See my other post of "slug
tuned" inductors. I'll bet they made a variable inductor. I was using some
air-core coils for a speaker crossover. I wanted to see what would happen if I
made it an iron core, so I took a handfull of finishing nails and stuck them
in the center of the coil. WOAH!!! I could vary the corner frequency a lot.
(so I found how many nails gave the right sound, then measured the
inductance... )  :-) Harry (also dumpster-diving tonight) Bissell

WeAreAs1 at aol.com wrote:
Roland made a few pedals that used Hall Effect sensors, back in the late 
70's/early 80's.  They were the "Rocker" pedals.  I guess they'd have to be 
"Alternative Rocker" pedals, or "Post-Punk Rocker" pedals if they made them 
now.  I never got a chance to try one out, so I don't know how well they 
worked.  As John Blacet may have pointed out, unpredictable linearity, 
temperature response, and part-to-part variations may be mitigating factors 
in the practicality of these devices.  I may have a schematic diagram for the 
Rocker Wah around here somewhere.  I'll have a look and get back to the list 
about it.

Michael Bacich

In a message dated 4/6/99 12:27:39 PM, you wrote:

<<Have any of you ever tried to use a Hall effect device instead of a
potentiometer or LDR? A magnet can be glued to the underside of the pedal,
and as it is depressed, the magnet is brought closer to the Hall eff
device. The closer it is, the stronger the magnetic field is, and thus the
output voltage.>>



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