I'm looking to build a [simple] high voltage power supply in order to make electrets via corona discharge. I'd like to be able to fabricate both positively and negatively charged electrets using this method, ideally with the same power supply requiring only minor configuration changes.
Right now, I'm leaning towards using a "wasted spark" automotive ignition coil which has both ends of the secondary winding exposed as such:
The logic behind opting for such a coil is that they're plentiful (i.e. cheap), can generate 30+ kV, and some are easily interfaced with needing only a 12V supply and a logic-level signal for pulse triggering.
Based on my understanding of the corona discharge method used to make electrets (but not the "triode" method), the insulator that you're making the electret from sits on a grounded metal plate, and then some electrode (be it a wire, or needle/s) sits above it at either a high negative or positive potential depending on the charge on the electret desired, and produces a corona discharge.
So my question essentially boils down to this: assuming nothing on the primary side of the transformer changes, is swapping the polarity on the secondary as simple and switching the two output leads, and grounding the appropriate leg?
Also, I may want the output to be DC. If I'm to add a blocking/rectifying diode and filter caps, can I still easily swap the polarity? If so, would I do that after the diodes+caps?