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reve

Joined: Feb 23, 2008 Posts: 147 Location: USA
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Posted: Mon Oct 10, 2011 11:39 pm Post subject:
Understanding Saw Animator imperfections. Subject description: (with handy scope shots) |
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(Sorry, I thought I was adding images right... clearly I was wrong)
Hey everyone.
So after a couple years of (successfully!) using my YuSynth Saw Animator, I finally got around to buying an oscilloscope... and trimming it properly.
What's weird is that different VCOs behave differently. Here's a shot of an MFOS VCO as trimmed as I could get it:
[img]http://electro-music.com/forum/phpbb-files/ds0000_108.bmp[/img]
Here is a TH XR-VCO with those same settings (this is, given the description on Yves' page, what I would expect):
[img]http://electro-music.com/forum/phpbb-files/ds0001_145.bmp[/img]
Here's the same TH VCO as trimmed as I could make it:
[img]http://electro-music.com/forum/phpbb-files/ds0003_248.bmp[/img]
So. Why the funny triangle shape on that first one? My initial theory was that the fall time was longer on the MFOS VCO, but after measuring that doesn't seem to be the case. I note that the MFOS VCO actually delivers more like 11.5 Vpp -- could that be the reason?
Again, no problems with the unit, just trying to understand things better.
| Description: |
| MFOS VCO as trimmed as possible. |
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DS0000.BMP |
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16.3 KB |
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110 Time(s) |
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DS0001.BMP |
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13.35 KB |
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103 Time(s) |
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DS0003.BMP |
| Filesize: |
17.09 KB |
| Downloaded: |
105 Time(s) |
_________________ - r. mosquito
SynthDIY Synthpop -> http://www.reverbnation.com/photovoltaik |
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yusynth

Joined: Nov 24, 2005 Posts: 1156 Location: France
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Posted: Tue Oct 11, 2011 8:15 am Post subject:
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As stated on the saw-animator page the module expects a sawtooth signal balanced around 0V, that is ranging from -5V up to +5V. Unbalanced sawtooth wont give a good result (MFOS VCO ?)
To help us understand the graph may be could you telle which curve (yellow, blue) correspond to which signal. _________________ Yves |
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reve

Joined: Feb 23, 2008 Posts: 147 Location: USA
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Posted: Tue Oct 11, 2011 9:06 pm Post subject:
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| yusynth wrote: | As stated on the saw-animator page the module expects a sawtooth signal balanced around 0V, that is ranging from -5V up to +5V. Unbalanced sawtooth wont give a good result (MFOS VCO ?)
To help us understand the graph may be could you telle which curve (yellow, blue) correspond to which signal. |
Hi Yves! Sorry; the yellow (top) is the output of the Saw Animator -- the bottom (blue) is the ramp wave being used as input. The MFOS VCO is indeed centered around 0v; but it swings between 5.8v to -5.6v. Is that extra 1.2 volts what's causing that foldover? _________________ - r. mosquito
SynthDIY Synthpop -> http://www.reverbnation.com/photovoltaik |
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yusynth

Joined: Nov 24, 2005 Posts: 1156 Location: France
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Posted: Wed Oct 12, 2011 12:54 am Post subject:
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| reve wrote: | | yusynth wrote: | As stated on the saw-animator page the module expects a sawtooth signal balanced around 0V, that is ranging from -5V up to +5V. Unbalanced sawtooth wont give a good result (MFOS VCO ?)
To help us understand the graph may be could you telle which curve (yellow, blue) correspond to which signal. |
Hi Yves! Sorry; the yellow (top) is the output of the Saw Animator -- the bottom (blue) is the ramp wave being used as input. The MFOS VCO is indeed centered around 0v; but it swings between 5.8v to -5.6v. Is that extra 1.2 volts what's causing that foldover? |
Yes it may cause the foldover, what you can do is to increase the value of R11 ,R8,R23 and R26 to 120K _________________ Yves |
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reve

Joined: Feb 23, 2008 Posts: 147 Location: USA
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Posted: Wed Oct 12, 2011 1:08 pm Post subject:
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Yves, thank you so much for taking the time to respond -- I appreciate it greatly! _________________ - r. mosquito
SynthDIY Synthpop -> http://www.reverbnation.com/photovoltaik |
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