Author Topic: Capacitors In Parallel With Clipping Diodes  (Read 2065 times)

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Paul Marossy

Capacitors In Parallel With Clipping Diodes
« on: November 16, 2009, 08:17:07 AM »
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?
_/\_/\_PJM_/\_/\_

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"Tone is in the fingers."

aron

Re: Capacitors In Parallel With Clipping Diodes
« Reply #1 on: November 16, 2009, 08:49:07 AM »
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...

Paul Marossy

Re: Capacitors In Parallel With Clipping Diodes
« Reply #2 on: November 16, 2009, 09:11:39 AM »
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:
_/\_/\_PJM_/\_/\_

www.diyguitarist.com
www.soundcloud.com/Paul-Marossy

"Tone is in the fingers."

teemuk

Re: Capacitors In Parallel With Clipping Diodes
« Reply #3 on: November 16, 2009, 09:12:28 AM »
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.

Paul Marossy

Re: Capacitors In Parallel With Clipping Diodes
« Reply #4 on: November 16, 2009, 09:17:34 AM »
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:
_/\_/\_PJM_/\_/\_

www.diyguitarist.com
www.soundcloud.com/Paul-Marossy

"Tone is in the fingers."