# Simple distortion unit

**URL:** <https://lookmumnocomputer.discourse.group/t/simple-distortion-unit/639>\
**Category:** DIY STUFF\
**Created:** [April 15, 2020, 8:41am UTC](https://lookmumnocomputer.discourse.group/t/simple-distortion-unit/639 "2020-04-15T08:41:11Z")\
**Posts on this page:** 1\
**Showing post:** 23

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**Author:** ![fredrik](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/fredrik/32/682_2.png) [@fredrik](https://lookmumnocomputer.discourse.group/u/fredrik)\
**Post date:** [April 18, 2020, 12:47am UTC](https://lookmumnocomputer.discourse.group/t/simple-distortion-unit/639/23 "2020-04-18T00:47:08Z")

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While you were preparing that 😃, I entertained myself by calculating the “effective resistance” of a generic small-signal diode, as a function of the voltage across the diode. I-V plots are common, but I couldn’t find a corresponding R=V/I plot so made one myself by stepping through a simulation:

 ![image](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/2X/f/fa3cc85ebcf7c1d1e67643fbef9ddc53d2ae81f7.png)

The red line is the cut-off frequency for the equivalent 10μF highpass filter (the properties of which keeps changing during the cycle, obviously).

Zooming in:

 ![image](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/2X/c/c0944d0d637835d3e26108cdd516a6ed2e800e80.png)

EDIT: Turns out the default diode I used has a relatively high reverse current and a lower forward voltage than your typical small signal diode (e.g. 1N914/1N4148) so should probably redo this some day to fix the reverse slope and knee voltage, but the general idea still applies.

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