[sdiy] Really Low, LFO

[Kyle Stephens]

Accuracy means getting, in this case, a specific frequency. Precision means it may be wrong (not necessarily), but at least it's consistently 'wrong'.

My ears are liable to pick out what "sounds good," independent of any specific value like 5.000Hz, and I'd like to be able to pick more than less the same point again and again when I set the pot to a given position, relatively free of stuff like temp drift or other second order interference.

I brought it up as I figured most material on function gens that slow would be scientific equipment where both those factors are important concerns.

Call it like a clock that's always 5 min fast - if you know it's off by that exactly much, it's still a perfectly usable clock.

Oh, and some more info here: http://en.wikipedia.org/wiki/Accuracy_and_precision


_Kyle

--- On Fri, 4/2/10, Chromatest J. Pantsmaker <chromatest at azburners.org> wrote:

> From: Chromatest J. Pantsmaker <chromatest at azburners.org>
> Subject: Re: [sdiy] Really Low, LFO
> To: "Kyle Stephens" <lightburnx at yahoo.com>
> Date: Friday, April 2, 2010, 2:04 PM
> What's the difference between
> accuracy and precision?
> 
> On Fri, Apr 2, 2010 at 1:51 PM, Kyle Stephens <lightburnx at yahoo.com>
> wrote:
> > Can anyone point me to some reading material on
> infrasonic oscillator design? I want to build a really low,
> low LFO, with a period of around half an hour (yes, _that_
> slow!).
> >
> > As HF designs have their share of issues that get
> worse in that spectrum, infrasonic has its problems too I
> would imagine - I just don't know what exactly they might
> be.
> >
> > For my app, accuracy isn't as important as
> precision/repeatability, though if both are possible then
> both are welcome.
> >
> > Closest I've found so far is this:
> >
> > http://tinyurl.com/yf9wzp3
> >
> > I reckon I can tailor it if I make the integrator cap
> several decades larger, to shift that 0.1Hz to 100KHz range
> several decimal places downward.
> >
> > I've a copy of AD's Nonlinear Circuits Handbook, which
> has some material on the topic, though nothing too specific
> on freqs beneath 1 Hz (half an hour is ~ 0.0001 Hz).
> >
> > I spoke to Prof. Lanterman about this a while back,
> and he recommended a microcontroller based solution, and
> while that's something I want to break into, it's a whole
> 'nother can of worms too. If this can be done in analog,
> it'd be a cool achievement and an enrichment exercise if
> nothing else... :]
> >
> >
> >
> > _Kyle (so slow it Herz?)
> >
> >
> >
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> >
> 
> 
> 
> -- 
> .sig
> -Chromatest J. Pantsmaker
> http://www.chromatest.net
>