[sdiy] Cheap frequency counter for oscillator calibration

[Karl Ekdahl]

I apreciate the answers i've gotten so far and i'm taking in the information.

However i should perhaps have pointed out that i will possibly be tuning a *lot* of oscillators several times a week. Thus i'm looking for the most time effective procedure that will still be quite cheap.

Granted i realize that you might already have given me that, i just wanted to clarify :)

Karl

--- Den tors 2010-04-22 skrev Florian Anwander <fanwander at mnet-online.de>:

> Från: Florian Anwander <fanwander at mnet-online.de>
> Ämne: Re: [sdiy] Cheap frequency counter for oscillator calibration
> Till: "Karl Ekdahl" <elektrodwarf at yahoo.se>
> Kopia: synth-diy at dropmix.xs4all.nl
> Datum: torsdag 22 april 2010 15:28
> Hi Karl
> 
> > I'm looking to buy a cheap ($50-$200) frequency
> counter mainly to be used for calibrating the span and base
> tuning of analog oscillators - any suggestions? Is there a
> better way of doing this then just measuring the frequency?
> To be honest: I would not recommend a frequency counter for
> spread tuning. In theory it would be ok, if you always tune
> the spread testing between the 0 Volt at the VCO-core and
> plus 1/2/... Volts. But in fact you will have always some
> kind of offset voltage at the output of the CV-mixer. This
> will cause the base frequency to be different with each
> change in the spread setting.
> This means for each turn on the spread you have to
> re-adjust the tune.
> 
> I prefer the following method:
> 
> Use a wide range chromatic tuner with a analogue meter like
> a Boss TU-12H (in fact the TU12-H is the only today
> available tuner which I would recommend).
> Connect the tuner to the output of the synth and listen to
> the synth through the headphone out.
> Now send (multiple) octave jumps and adjust the spread
> trimmer and whatch the tuner: It does not matter WHICH note
> exactly is displayed (it may be a completely different notes
> at different settings of the spread trimmer), but you trim
> it until you hear a clean octave and the meters needle does
> noe longer move when the octave jump happens. The absolute
> pitch of those two notes does not matter at that moment.
> When this is done I set the absolute pitch, and - if
> requires - the trimming of octave switches.
> 
> I recently tuned an OBXa (16VCOs !) in around 40 minutes
> with this method.
> 
> Flroian
> 
>