[sdiy] Auto Center waveforms

[David Anderson]

And there's a DC blocking cap on the output.

David Anderson wrote:
> Funny you should ask. I just reworked an old guitar effect from E&MM 
> that uses a voltage divider to create a ground. The signal input and 
> output shields ("ground" relative to the guitar signal) are connected to 
> the V- of the circuit. Since it's powered by a single 9v, the circuit is 
> powered by +/-4.5v. Of course, this analog. Not sure what the equiv 
> would be for digital except some input signal buffering and offset.