[sdiy] Frequency counter

[Paul Perry]

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