[sdiy] Thomas Henry XR-2206 VCO Page Up

[Scott Stites]

Thanks, Ian!  

Yes, that lower octave was the heartbreaker.  Tuning for perfect flatness down that low would shift things enough on the high end where the tracking just wasn't terribly good beyond five octaves.

I guess the main reason one would want to worry about the low end like that is that the ramp wave (from the skew) is double the frequency, so with the wave skewed to the octave up, it would still have the same amount of error.

Of course I think it's possible to get a ramp wave at the fundamental frequency, but that takes a bit more circuitry than Tom was willing to put in.  

Cheers,
Scott


-----Original Message-----
>From: Ian Fritz <ijfritz at comcast.net>
>Sent: Jun 29, 2006 11:40 AM
>To: Scott Stites <scottnoanh at peoplepc.com>, SDIY <synth-diy at dropmix.xs4all.nl>
>Subject: Re: [sdiy] Thomas Henry XR-2206 VCO Page Up
>
>At 10:02 AM 6/29/2006, Scott Stites wrote:
>
>>We were able to get around 5 musically useful octaves out of it - it would 
>>be much better if the low end would have cooperated more, but we think 
>>that's all the XR-2206 would provide without running afoul of the law of 
>>diminishing returns - IE, it would start to increase in parts 
>>count/circuit complexity, which Thomas reasoned would defeat the original 
>>intent of the circuit (a very simple, easy to build VCO with some neat 
>>features).
>
>
>Hmmm... looks better than 5 octaves to me.  Within 0.1% from 1V to 8V.  I'd 
>call it 7 octaves.
>
>Nice work!
>
>   Ian 
>


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