Frequency changing stuff...

[D.V. Mitchell]

Hi...
I've been reading this page for about six months, under various addresses...
It's really good, and helped me e.t.c....
I've got a question, I've thought up two projects, one of which will be too
complicated for analogue, so I'll probably use DSP's...
But the other can be done in either analogue or digital (I hope)...
I'ts not really a synth circuit, (well for the application I'm going to use it
for, but the end circuit could be modified to give some effects...
Basically I need to get a full range audio signal, and increase it's frequency
by two or three hz...
err...
My first thoughts, were get a computer to do it, but thats not what I want...
It would be really cool, if it could be analogue, e.g. small, less complicated
that building a single board computer, cheaper to build, better quality
(maybe)...
I need it to be of extremely good quality, as if it wasn't it would be no good
for the application I've got in mind for it, and the system would be better off
without it...
Does anyone have any ideas, of how such a feat, could be achieved with analogue
electronics...

Also I built one of them 'State Variable Filters' In the TI OpAmp data book...
As my maths isn't all that hot, I used the rules of thumb (given below it), and
built the filter...
But now, it sort of works, (sometimes), but then other times all the signal
paths seem to 'clog up' with the supply, and inbetween D.C. voltages...
Very confusing...

Thanks...

Damian Mitchell
dvm1 at le.ac.uk