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Author Topic: Capacitors In Parallel With Clipping Diodes  (Read 1659 times)
Paul Marossy
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Capacitors In Parallel With Clipping Diodes
« on: November 16, 2009, 12:17:07 PM »

There is one pedal mod I have done where a 0.001uF capacitor is placed in parallel with an LED acting as a clipping diode in an opamp feedback loop. Can anyone tell me what affect this is supposed to have? Is that supposed to smooth out the clipping a little bit?
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aron
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Aron Nelson


Re: Capacitors In Parallel With Clipping Diodes
« Reply #1 on: November 16, 2009, 12:49:07 PM »

Yes, check out:

http://geofex.com/Article_Folders/TStech/tsxtech.htm
Quote
The small 51pf capacitor across the diodes acts to soften the "corners" of the clipped waveform somewhat

and more...
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Paul Marossy
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Re: Capacitors In Parallel With Clipping Diodes
« Reply #2 on: November 16, 2009, 01:11:39 PM »

Thanks! I thought that was the case, but I wanted to check to be sure. I'm going to read that GEO article now.  icon_razz
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teemuk
Posts: 338


Re: Capacitors In Parallel With Clipping Diodes
« Reply #3 on: November 16, 2009, 01:12:28 PM »

It's a low-pass filter.

Quote
The small 51pf capacitor across the diodes acts to soften the "corners" of the clipped waveform somewhat

Which is an effect of the low-pass filter. The sharper the "corner" of a clipped wavew the more higher frequency harmonics there are present in the signal.
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Paul Marossy
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Re: Capacitors In Parallel With Clipping Diodes
« Reply #4 on: November 16, 2009, 01:17:34 PM »

It's a low-pass filter.

Quote
The small 51pf capacitor across the diodes acts to soften the "corners" of the clipped waveform somewhat

Which is an effect of the low-pass filter. The sharper the "corner" of a clipped wavew the more higher frequency harmonics there are present in the signal.

Cool, that will get me exactly what I am trying to achieve.  icon_cool
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