I recently did a little project up after a certain WBO2 controller kept hitting some kind of race condition which ended up only running the controller properly about once every 2-3 starts.
The circuit is fairly simple, and actually fairly similar to another open source WBO2 design I later found while trying to debug my circuit. The parts requirements are simple, consisting of:
A NPN darlington BJT or N-channel FET able to carry 2 amps
A quad opamp (rail to rail is better, but not necessary)
Some form of Ardunio capable chip/board (3 ADC, and 3 PWM and 2 on/offs)
A small handful of resistors and capacitors
For my use, I initially did the prototyping with the Teensy++ 2.0, but I have plans to change it around to work with regular AVR C (with Arduino sketch option) on an ATmega167, but for the current setup I'm using, I get a sample rate of about 250Hz with enough accuracy to compare the readings I get out with my previous WBO2 controller (when it worked).
https://github.com/Hell-Fire/WidebandO2
Schematics are in gEDA gschem format, feel free to fork and push requests up for other Arduino family boards and chips
![Smile :)](./images/smilies/icon_e_smile.gif)