phasers (was: Mutron)
costello at seanet.com
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
More information about the Synth-diy