Strange Hall effect CV pedals

[Harry Bissell]

Harry Bissell writes: Don't go weird on me guys... Texas used to make a linear
hall output device in a TO-92, but do they still?? This would be even harder
electrically than an opto pedal. While you drift into left field...
going...going... how about the LVDT (linear variable displacment transformer)
You need an oscillator to drive it, syncronous rectifier to demodulate it,
etc... but it is "non contact". An easier method might be an RF oscillator
detuned by putting an iron slug into a fixed coil, and changing the
inductance, then decode that. Also non contact... (but not non-silly). I'd
still go with the Ernie Ball old time dial cord around a pot. If you worry
about life use a really good optical encoder thay're good for millions of
cycles...  :-) Harry Bissell

Paul Perry <pfperry at melbpc.org.au> wrote:
At 04:44 PM 6/04/99 -0300, edu silva 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.

Yes, it works.
Make sure the Hall device you get is linear, nearly all are for switching
and have a built-in comparator and digital output.

paul perry Frostwave p/L melbourne australia

BTW if you are thinking of using a pedal in a mangrove swamp, this is the way.
Also, for a nice hand-operated lfo, spin a bike wheelpast one with magnets
stuck on. 


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