Motorized Barberpole Phaser (was Re: Another kind of Pha

Bob Schrum Bob.Schrum at
Wed Jan 14 18:44:56 CET 1998

At 1/13/98 8:36 PM Sean Costello <costello at> wrote:

>What if you constructed an actual "motorized phase shifter," ....  I think
>that a similar circuit may have been used to create vibrato in some older
>organs. Think of it as a cross between a Univibe (the photocells) and a 
>Leslie (the rotating drum).

Look no further than the Hammond "Scanner Vibrato" used on the B3 et al.  It 
had a motor-driven rotor, capacitively coupling stators connected to taps 
along a delay line.  The Vibrato settings take the signal straight from the 
scanner, and the Chorus settings mixed in a little of the dry.  There are 
better descriptions available on the Net--even complete schematics for the 
B3 in PostScript or PDF files somewhere out there--I downloaded them 
probably a year or so ago.

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