How do you make positive ions? I found a kit device that is made of a bunch of capacitors and diodes that's supposed to make negative ions (it says to reverse the diodes to make positive ions) how does this work? Wikipedia and HowStuffWorks weren't much help. Wikipedia explained what diodes do, but it didn't explain why it's direction-specific. In other words, what makes the cathode a cathode and the anode an anode?