phasers (was: Mutron)

Sean Costello costello at
Wed Mar 18 05:59:54 CET 1998

Haible Juergen wrote:

> Sorry for the delayed reply.
> This was a great list of phasers you posted !


> > - LM3900 configured as phase shifter (per Serge Tcherepnin's patent -
> anyone >tried it yet?  Looks like the easiest method of all)
> Do you have the patent # at hand ?

Set your browser to the heart of the sun - I mean, to

This has the entire patent (U.S. No. 4,306,480) viewable online.  It mostly
concerns itself with a guitar synthesizer-type device, but it has some nifty
applications for the LM3900.  Note:  the Serge Wave Multiplier secrets are
partially contained in this patent.

I found another phaser type schematic, in a Donald Leslie patent.  This one
uses a capacitive scanner, like the Hammond, and a phase shift network.
Unlike the Hammond, the phase shift network is a broadband phase shift
network, with 0, 90, 180 and 270 degree outputs, as used in a frequency
shifter.  The result is true frequency shifting, with the amount of shift
dependent on the rotation speed of the scanner.  This could be the core of a
true "motorized phase shifter," that produces barberpole phasing.  You can
look up the patent at the above IBM site, which is one of the greatest sites
on earth.

Sean Costello

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