[sdiy] Frequency counter

[James Patchell]

Personally, I prefer using a strobe tuner for adjusting the pitch of VCO's 
as you instant feedback as to which way the pitch is going.  There is, of 
course, the cost problem.  I would keep an eye on Ebay, as they do show up 
there quite often.  A Conn Strobe tuner, when they are working and in good 
shape is real nice...but if it is in bad condition and not working, they 
can be a night mare.  The Peterson tuners are also very nice.

At 09:56 AM 1/29/2005 -0600, John Loffink wrote:
>Paul's comments regarding traditional frequency counters are correct.  They
>are optimized for radio frequency work and use the simple gate/count
>technique for frequency counting, which is too slow for audio.  I had an HP
>5314A Universal counter with 0.1 Hz accuracy, but it took 10 seconds between
>gates for the reading to update.
>
>Modern DMMs are somewhat better for audio range work, though check the
>accuracy before buying.  You want better than 1% accuracy when tuning VCOs,
>for instance, and that's what most brands of DMM provide for accuracy.
>
>The Extech line of DMMs have frequency resolution surpassing the name brands
>such as Fluke.  Model MT310 has 0.1% accuracy and 0.1 milliHertz resolution,
>for instance, and that's in the sub $100 range of DMM.  The MM560 has +/-
>0.008% accuracy and 0.1 millHertz resolution.  Some of their units cover the
>LFO range, and some do not.  Check the specs at their web site.
>
>http://www.extech.com/
>
>John Loffink
>The Microtonal Synthesis Web Site
>http://www.microtonal-synthesis.com
>The Wavemakers Synthesizer Web Site
>http://www.wavemakers-synth.com
>
>
> > -----Original Message-----
> > From: owner-synth-diy at dropmix.xs4all.nl [mailto:owner-synth-
> >
> >
> > From: "Mikael Mørup" > Are the ones that are build into the better digital
> > handheld
> > > Volt/Amp/Ohm meters good enough for synth DIY work ?  Do
> > > they have the required precision ? do they cover the low
> > > LFO range ?
> >
> > A problem with 'common' freq meters, is that they are intended for radio
> > frequency work.
> > And they usually total cycles over 1 second.
> > So that isn't too useful for LFO examination!
> >
> > The frequency meter you wnt for LFO examination is one that has a "period"
> > function, that
> > is to say, it has a mode where you can check the time taken for a cycle to
> > run, then
> > you just invert this to get the frequency.
> >
> > I've only got an RF model, so I use the scope to check the LFO rate.
> > Fortunately, the lower the LFO gets, the easier it is to tell the freq,
> > just
> > by
> > counting seconds! you don't often need any precision in this application.
> >
> > If you want to calibrate your VCO with a freq meter, a RF meter won't give
> > enough
> > accuracy (unless it has an extened time feature, where it counts a lot
> > longer than a second),
> > and a DMM definitely won't do. I believe most DMM freq counters work like
> > a
> > tachometer, they have a monostable pulse generator that spits out a little
> > charge for each
> > pulse & then averages the current (more pulses = higher freq). Not
> > precision.
> >
> > For calibrating purposes, zero beating with a digital synth or organ might
> > be the easiest.
> > paul perry Melbourne Australia
> >

         -Jim
***************************************************************
http://www.oldcrows.net/~patchell

***************************************************************