[sdiy] Cheap frequency counter for oscillator calibration

[johnspeth at yahoo.com]

I've have used a free app you can find on the web on my Windows computer using the mic input.  I was successful and it was easy to get the audio input level to work on my computer.  Of course, YMMV.

I don't have the source of my app (I'm at work now) but a web search could probably get you good hits quickly.

JJS



----- Original Message ----
> From: Karl Ekdahl <elektrodwarf at yahoo.se>
> To: synth-diy at dropmix.xs4all.nl
> Sent: Thu, April 22, 2010 7:53:37 AM
> Subject: Re: [sdiy] Cheap frequency counter for oscillator calibration
> 
> 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 <> href="mailto:fanwander at mnet-online.de">fanwander at mnet-online.de>:

> 
> Från: Florian Anwander <> href="mailto:fanwander at mnet-online.de">fanwander at mnet-online.de>
> 
> Ämne: Re: [sdiy] Cheap frequency counter for oscillator calibration
> 
> Till: "Karl Ekdahl" <> href="mailto:elektrodwarf at yahoo.se">elektrodwarf at yahoo.se>
> Kopia: 
> > href="mailto:synth-diy at dropmix.xs4all.nl">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
> 
> 
> 


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