[sdiy] Real slow LFO ICs?

[harrybissell]

I'm assuming you are still considering the 1Hz - 1MHz from the app note.
Looking at the data book (not the app note) I don't see the sine converter.

There is one shown on the CA3280 sheet with .37% distortion...

Most CA3080 sine converters do not make a really pure sine.. it is either
distorted
at the zero cross or at the peak...

Temperature stability ??? Probably not perfect...  do you need stability in a
really
LFO ???

H^) harry

Michael Boracci wrote:

> 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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