[sdiy] Frequency meter (was Re: Anyone in the UK used RS Calibration Services?)

[Neil Johnson]

Hi Tom,

> In a similar vein, I often find myself in need of a high accuracy frequency
> meter for audio and sample clock frequencies. 0-25KHz for sure, and 0-200KHz
> would be nice. Presumably there are expensive pieces of test equipment
> available that do this job, but does anyone know of a cheap/accurate way to
> do it? My definition of "accurate" would be something like "so I can see
> errors of a cent or less" I suppose - e.g. an order of magnitude better than
> I can manage with my ears. Otherwise there's really no point.

What is your definition of "cheap"...?

I picked up an HP 5334A counter off ebay a while back for not much
which has 8-digit precision.  For audio use and your sanity you really
want a reciprocal counter so that at low frequencies you aren't
waiting too long for a reading (the reason why I upgraded from my old
Racal Dana counter).  If you want high accuracy, then you're entering
the realm of GPS-disciplined reference clocks to give to a very
accurate 10MHz timebase.  Or you may be happy enough with the internal
crystal oscillator.

What you get in a fancy box are things like a great analogue front
end, multiple channels, various triggering and counting modes, maybe
some maths functions, various gate functions, etc.

Neil
--
http://www.njohnson.co.uk