My first negative ion generator has been in operation for two years and has been a success. I’m now putting together a second using physically smaller capacitors and have decided to paint the cap-diode ladder with a conformal coating:
http://www.vitency.com/electronics/naig.html
After checking the stores, I’d guess that most of the spray cans contain a common thinned-out polyurethane with a fancy label and a top-dollar price.
It’s quite likely that a good-quality hardware-store can of polyurethane would serve just as well, perhaps better. I’d prefer to brush on a thick coat rather than go through the mess of spraying. I also note the availability of acrylic coatings, some or all of which I know are water-based.
Checking the volume resistivity and dielectric strength of poly supports my views - not sure about acrylics. Does anyone have practical experience or specialized knowledge of these things? With thanks for any replies.
From http://4hv.org/e107_files/public/149083 … ysics_.pdf
… it looks like polyurethane has around 50 times the electric breakdown strength of air, so even a thin coating will be useful in your application. A thin coat will also cure/dry faster.
-Mark
Thanks for that - useful. Frustration eventually prompted me to finally build something I’d been putting off for yonks, a Mains Breakout Box:
http://52midnight.com/MPBB/home.html
This allowed me to poke around in a dried coating at mains potential to prove that whatever leakage current there might be was too small to matter. I’d been concerned that additives may have compromised the resistivity, but that’s darned hard to do unless you include powdered metal or something similar.
Liquid electrical tape? You can paint that on as thick as you like.
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Liquid electrical tape
Interesting. Didn’t know about it. Thanks. I’d also thought of potting compound, so there are a number of options.