circuit building blocks -- phase reversal

[caress]

i think i understand a bit about phase and polarity switching, yet am unsure about fully applying it

using r.g.'s page on polarity reversal... i have a few questions
http://geofex.com/Article_Folders/polarity_reverser/polarity_reverser.htm

if i plan on using a dual 12V supply on the opamp, would i set Vbias to reference ground?
would 100k resistors be a good starting place for R1-R3 and 1M for Rbias?
do i need Rpulldown if this is wedged somewhere in the middle of a circuit?

[earthtonesaudio]

i think i understand a bit about phase and polarity switching, yet am unsure about fully applying it

using r.g.'s page on polarity reversal... i have a few questions
http://geofex.com/Article_Folders/polarity_reverser/polarity_reverser.htm

if i plan on using a dual 12V supply on the opamp, would i set Vbias to reference ground? Yup.
would 100k resistors be a good starting place for R1-R3 and 1M for Rbias? Yup.
do i need Rpulldown if this is wedged somewhere in the middle of a circuit? Probably not, but it might help in certain cases.

[caress]

cool.  thanks alex