[sdiy] r/c phase shift on face (esoterica could save the pie)

[Magnus Danielson]

From: Chris K <synth at wayfar.net>
Subject: Re: [sdiy] r/c phase shift on face (esoterica could save the pie)
Date: Wed, 18 Apr 2007 11:02:15 -0700
Message-ID: <46265D27.1070602 at wayfar.net>

> I don't know how much this will help, since its R/C based, but theres a 
> good circuit and information on page 78 in "The Art of Electronics" that 
> covers a variable phase 0 to 180deg.

That is one of many forms of the polyphase filter I was mentioning. It looks
strangely bizare compared to normal filters, but if you read up on
Mike Gingells PhD and supporting articles (read them first), you might
finally get it. The Art of Electronics doesn't properly refer to it.
Here is a drawing without any values assigned:
http://users.vnet.net/gingell/polyphas/polyphas.html

Hans Summers have used it in radio filters (he has schematics too):
http://www.hanssummers.com/radio/polyphase/index.htm

Further reading which also might be of interest is that of Pim Niessen:
http://home.planet.nl/~niess153/Polyphase_networks.htm
He also has an Excel spreadsheat to calculate with. A bit complex, so one
probably needs to read the paper.

Cheers,
Magnus