[sdiy] Real slow LFO ICs?

[Michael Boracci]

I have seen the output of the 3080 and the sine output was not very pure (
switching glitch at zero crossing point )at higher frequencies around 10khz.
Does anyone know if this is true for the sub-audible range as well?

Any word on temperature stability?

MB

-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of harrybissell
Sent: Monday, October 27, 2003 9:01 PM
To: Tim Parkhurst
Cc: 'Paul Perry'; synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] Real slow LFO ICs?


iirc... the trimmer caps are all for the high frequency range (compensation)
and could be removed completely for a very LFO... or even over a reasonable
slice of the audio band.

H^) harry

Tim Parkhurst wrote:

> Look for the Intersil CA3080 spec sheet. One of the applications they show
> is a voltage controlled function generator with a 1,000,000 to 1 range!
The
> timing cap portion is real tricky in that it uses 3 adjustable caps, but
> perhaps that could be simplified for lower frequency use and the range
could
> be brought down in to "real slow" range (depends on the minimum input
> current for the 3080?). I just thought it was interesting because it
showed
> the 3080 used as a voltage controlled current source with a VERY wide
range.
> I think it would make a cool LFO, and the current source might just be the
> ticket for a wide range VCADSR.
>
> Tim Servo
>
> ********************************************************
> > -----Original Message-----
> > From: Paul Perry [mailto:pfperry at melbpc.org.au]
> > Sent: Monday, October 27, 2003 3:06 PM
> > To: synth-diy at dropmix.xs4all.nl
> > Subject: Re: [sdiy] Real slow LFO ICs?
> >
> > At 10:14 PM 27/10/03 +0100, Achim. wrote:
> > >> Hi, I am looking for a super-simple LFO IC... or multiple LFOs in a
> > >> single package.  sine or saw output will be fine, must be able to run
> > >> in the sub-1hz range.
> > >A microcontroller with PWM ouput or a built-in DAC would probably be
> > >the easiest solution. In both cases you can achieve higher resolution
> > >than the typical 8..10bit by using multiple outputs.
> >
> > Depending what you want to do with the LFO.... a very slowly stepped LFO
> > is very noticeable indeed. This is just about the only thing I wouldn't
> > want to do with a micro, but I'd like to hear more opinions.
> > The 3080 is good, but the range is (in practice) only about 1000 to 1.
> > (was there a work-around for that? Transistor as timing resistor?)
> >
> > paul perry Melbourne Australia
>
>
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