I’ve been really fascinated lately by magnetic and electric fields and how they interact (mostly influenced by my interest in magnetohydrodynamics).
One relatively simple but fun project is an air ionizer. The one I’ve built converts mains voltages (~120VAC @ 60Hz in the US) to something on the order of a few kilovolts at a very low current. At the end of the discharge needles connected to this high voltage, we generate an ion wind.
You should be experienced in dealing with mains voltages if you are attempting this project. There are going to be live wires, and there’s a big potential for shocking yourself if you’re not extremely careful. Be smart!
To build my ionizer I used some .1uF capacitors each rated at 275 Volts (pictured below). This rating is far lower than the thousands of volts generated, but a couple of sources online indicate that, because these are “mains suppression capacitors,” this is okay. I picked them up from Digikey for $0.35 a piece.
The diodes I used are just jellybean 1N4007s.
First I wired three lines of ten capacitors in series. We are full-wave rectifying the mains voltages, so we need three different columns of capacitors.
Next, I began wiring the three columns together, as shown below. If you want to make a negative air ionizer, the stripes on the diode should be pointing towards where you are going to plug in the mains voltages. For positive ionization, the stripes should point towards the emitter.
Next, you must attach your mains voltages. Connect ground to the center, then live to one side, and neutral to the other. It does not matter which way you do this, as long as ground is centered.
To finish the project, add a large valued resistor (I used 1 Megaohm, you may want to use somewhere on the order of 10 Megaohms) to the emitter in order to limit the current. It’s important for something fairly large to be there, but in my experience even 1 Megaohm significantly reduced the current to a safe value.
For obvious reasons, the invisible ion wind is a tricky thing to catch on video, but you can certainly feel it by placing your hand a few inches in front of the emitter. Have fun!