[sdiy] quadrature VCO - a different approach

[Magnus Danielson]

From: "JH." <jhaible at debitel.net>
Subject: Re: [sdiy] quadrature VCO - a different approach
Date: Sun, 2 May 2004 19:57:34 +0200
Message-ID: <002c01c4306f$142d9050$527fb9d9 at jhsilent>

> > > Still working on my FS-2 project (it goes very slow - most of my spare
> time
> > > is consumed by that big project of building a house now),
> >
> > Now, tell us... any neat modules in that project? ;O)
> 
> No, it's just a new frequency shifter.

The HOUSE Jürgen, the HOUSE!

You are among nerds, must I point such obvious facts out to you? ;O)

> 2 channels this time, so it can either be used in stereo, or as a chain
> upshift -> fixed filter (bank) -> downshift to get some kind of voltage
> control on fixed filters. This won't be able to shift full-range audio
> signals over a wide range, of course, but I reckon it could be
> very useful to slightly move the notches of a comb filter, for instance.

Ah.

I really should build myself a frequency-shifter. I really should.

> > Have you looked at the Polyphase way of doing things? There is both ideas
> for
> > the phase-difference-filter as well as for direct oscillators.
> 
> I have downloaded this back then, but never read it all. The dome filter
> approach works just nicely. In retrospect, it's no big surprise: 2 x 6 stages
> make an excellent (0.3deg phase error) filter for 3 decades (15Hz ... 15kHz),
> so with another 2 x 6 stages I can get another 3 decades. It all fits on a
> 16cm x 10cm veroboard.

OK.

Cheers,
Magnus - slightly detuned by the Banyuls after dinner :->