[sdiy] On cloning, and the Oberheim VCO

[mark verbos]

It was a long time ago. I don't remember what troubles I had, but I  
did get it running.


mark



On Apr 15, 2008, at 12:14 AM, Aaron Lanterman wrote:
>
> On Apr 15, 2008, at 12:00 AM, mark verbos wrote:
>
>> I'd suggest you look at the Kobol oscillator on my page
>>
>> http://www.simple-answer.com/DIY.html
>>
>> It's basically the same one that's in an SEM, but with OPamps  
>> instead of those transistors for that buffer. Sadly, you'll notice  
>> that it uses wider supply rails than +/-15, like the SEM. They  
>> also used a 3086 for the NPNs in the core.
>>
>> Incidentally, Q4 does not invert the signal. Q5 and Q6 are a  
>> comparator, R29 is adding positive feedback for hysteresis, Q8 and  
>> Q9 are switching not buffering.
>>
>> My guess is that they used transistors because they are small and  
>> cheap. It's probably a fatter, driftier sounding oscillator for  
>> it. RSF used SSM chips in every part of the Kobol except the  
>> oscillator, it's a GREAT sounding box.
>
> Excellent - I guess you got this running without any troubles?
>
> - Aaron
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