[sdiy] Real slow LFO ICs?

[Tim Parkhurst]

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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