Mon Dec 20 14:17:48 EST 2010

Distortion board rev1

Board shortcomings:

   - No connectors or holes for in,out,GND,Vcc

   - No output coupling cap.

   - Feedback resistor hard to replace by pot.  Also needs pot in

   - No feedback cap


   - Diodes are the wrong way.  Together with the biasing this made
     the opamp saturate.  Fix: replace 100k R5 with 22k to bring the
     bias point near 1/2 Vcc.

   - Schematics wrong: the 2nd opamp is a ground following buffer ;)

   - After different biasing, 10K from out to ground is necessary to
     enable class A, only upper transistor in LM358.

   - 1/2 ref needs regulation.