Although I chose an on / off / on circuit, the amount of distortion can also be controlled by simply adding a POT. Now the effect can be adjusted, and the desired asymmetry "dialed in." It should be noted that I've add a fixed "mix control" to mine--the two resistors. But a variable control might be of value....
And there are many diode types we haven't covered: zener
, other LED colors
, etc. Even MOSFET transistors
have a voltage drop.
Flipping the asymmetry--switching the directions of all the diodes, will also have an effect. This can emphasize odd or even harmonics. Choose whichever sounds best to you.
There are a great many variations of diode clipping circuits. Here are a few links to get you started... :
-- DIY Fever: Diode Clipping
-- MOSFETs as diodes
-- AMZ - Diode clipping staturation controls
-- AMZ - "Warp" controls--balancing diode clipping
-- AMZ - Mosfets and Zeners as clipping diodes