Double check all the capacitor values again. A 68pf cap is in the
feedback loop of the sawtooth buffer op amp. If this is a large value
by mistake it would act as a low pass filter, cutting off higher
frequencies. I used 18pf there. It is only to prevent parasitic
oscillations.
Richard Brewster
josh wrote:
feedback loop of the sawtooth buffer op amp. If this is a large value
by mistake it would act as a low pass filter, cutting off higher
frequencies. I used 18pf there. It is only to prevent parasitic
oscillations.
Richard Brewster
josh wrote:
>Thanks for the reply,
>I'm double checking everything but nothing seems abnormal. When i
>apply CV it changes octave correctly and can be tuned but the lower
>notes have so much gain that the upper haves of the signal are clipped
>and the output is about 6V pk-pk. when i play the higher notes the
>gain starts to decrease. two or three octaves up the amplitude is less
>than 1V pk-pk. Should i get a clean saw with this? Is decreasing gain
>normal for the higher octaves? I'm going to go on the assumption that
>i have an improperly placed resistor. Does amyone have any suggestions
>or things to check to narrow down the fault?
>
>--- In cgs_synth@yahoogroups.com, sasami@h... wrote:
>
>
>>I suggest you look elsewhere for the fault - more likely a wrongly
>>
>>
>placed
>
>
>>component. Using 2% resistors will at most cause a slight difference in
>>stability. It certainly won't be the difference between it working
>>
>>
>or not.
>
>
>>Ken
>>
>>
>>
>>>Hey. I just built the ken stone vco and i am trying to test it. I seem
>>>to be having a problem. The oscillator with no CV applied looks
>>>clipped. When i add higher CV voltages the amplitude decreases and it
>>>is no longer clipped. It also does not give a clean saw output. It
>>>looks more like a half rectified sinewave. I believe my problem might
>>>lie in that i used alot of 2% metal film resistors since i had alot of
>>>them already. Does anyone have any sugestions.
>>>Thanks
>>>Josh
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>The CGS Modular Synth home page: http://www.cgs.synth.net/
>>>
>>>Yahoo! Groups Links
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>_______________________________________________________________________
>>Ken Stone sasami@h... or sasami@c...
>>Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
>>Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>
>>
>>
>>
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