[sdiy] frequency counter

[Magnus Danielson]

From: harrybissell <harrybissell at prodigy.net>
Subject: Re: [sdiy] frequency counter
Date: Sun, 27 Jun 2004 12:29:58 +0000
Message-ID: <40DEBDC5.2CE3FD2E at prodigy.net>

> I'm one of those who question the usefulness of the frequency counter. I use
> a musical tuner, sine wave generator, scope (lissajous)... and my ears as a final
> 
> QC check.

I hope you mean that you find their usefulness in the context of normal synth-
trimming somewhat questionable. I'm sure you find plenty of use for them in
other contexts. ;O)

> I set the sine wave generator to a midrange reference frequency. Use the Tuner to
> check
> the reference... then use the lissajous patterns to take it from there.  The
> lissajous patterns
> are very similar to a strobe tuner... it is a matter of pattern recognition from
> then on.
> 
> I think that freq counters are too hard to intrepret (sure they're OK for A=440).
> And too
> slow to settle to reasonable precision.
> 
> oh... and mine is broken :^P

That's it then! A broken frequency counter leaves you out in the woods with all
kinds of strange creatures... obviously!

But really, for 440 Hz and their octave relatives counters is kind of usefull,
but for other things they are not as easilly useful. The main reason is that
they display the wrong thing, but also the usually have a too poor update-rate
for a fruitfull speed in trimming. Then a tuner is much more usefull. It not
only displays the right format, but they are quick to catch on to changes.
For guitar-tuning that's strictly necessary, so no wonder that this method has
been taken as a reference.

Personally I lack a tuner but has a pretty darn good frequency counter.

However, tuners isn't very usefull in lab-type measurements.

So, it comes down to the application. Some tools are great, but they are not
suitable to all applications. Some is really speciallized and may collect dust
for long times, but when you need them, oh boy, then nothing else will rock as
much as then!

> I would like a frequency counter to determine the linearity of an unknown VCO
> design... lissajous patterns don't help much.

For that you need to combine a DMM and a frequency counter with a voltage-
source, preferably programable. I have all that, with the GPIB-cables on the
back in place... but no GPIB-card! If I only had a GPIB-card it would be a
matter of "a few lines of code" and I could be doing nice little app's for that
purpose.

Cheers,
Magnus