[sdiy] 90-degree phase displacement network calculations

David G Dixon dixon at mail.ubc.ca
Tue Feb 9 20:49:32 CET 2021

Hello SDIYers,

To close the (long) discussion on phase displacement networks, I would like
to alert you to a YouTube video I posted a few days ago showcasing the new
frequency shifter that I built with two PDNs -- a 12-stage,
3-order-of-magnitude unit for audio signals, and an 18-stage,
5-order-of-magnitude unit for modulating signals which goes down to 0.1 Hz.


As shown in the video, the 18-stage unit generates quadrature signals which
are identical to externally supplied quadrature sine waves (from an
oscillating 4-pole filter).  Also, giving the option for internal or
external modulating signals creates opportunities for some very interesting
sounds from this unit.  Finally, using a PDN to generate quadrature from
external signals really expands the possibilities of controlling the
frequency shifter, including using two sine waves mixed together to get two
sidebands.  I'm very pleased with how this unit works.

If anybody wants the PCB shown in the video, I'm offering them for $200,
fully stuffed and tested.  I'm making them in the 5.3" x 6.0" version as
shown, and also as a stack of 3 PCBs 2.0" x 6.0".  If you are interested,
please email me privately.  Sorry for the sales plug.

Dave Dixon
aka Doc Sketchy

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