Emitter design for negative ion generators...

I have a commercial bionair HEPA filter with an ionizer that uses a single needle. I think if you need a special electrode like the one in the link, you are probably producing too many ions for regular use in an occupied room. I'm not a big believer in the benefits of negative ions, and I'm sure it's possible to do harm with too high a concentration.

I would think that around 4-5kV on a single stainless steel needle would be fine. If you can hear it hissing in a quiet room it's working, and if you can smell it, it's producing ozone.

Use some spikes and ignore the bullshit. Just remember what youre trying to achieve.

Emitters dont need trimming btw.

Regards, NT

I'm guessing (not looked at link) that they are talking about carbon fiber. "Carbon Fiber Electrode" ? There are various sellers selling raw carbon fiber on ebay, for little money.

One or two needles is quite satisfactory. Ideal voltages are between 4,500 to 5,000 volts. Voltages greater than 5000 volts creates large amounts of OZONE. This can be Very Dangerous!

Take care..........Gary

Thanks to all of you for the replies...was appreciated. Yesterday i've bought a ready-made air purifier based on negative ions technology. It's not that i'm too lazy to build one myself, but i couldn't resist when i saw it. I was shopping for a humidifier and went out of the store not only with a humidifier but with this ionizer! Was all air quality-related expenses, finally :-)

I've saw the product a few years ago on TV and believe me, after 36hours of operation, let me say that it works! The surrounding collector band is positively charged to attract the dust that have been negatively charged with the negative ions (from three needle that acts as the emitters...they didn't used CFE emitters like on the website you've seen on the link in my previous post). It collected a lot of dust already wich seems promising. Ian...you're probably right about the defenition of "CFE". Even if they don't specify the material, they state: "The long-life CFE ion emitter used in this model is made from a high-tech, space-age material that is virtually maintenance-free." Theese days, when we speak about space age material, carbon fiber is often mentioned. I don't know the voltages used for the one i've bought, but it produce very little ozone...only a slight odour is noticeable whithin a feet from the unit.

If the unit still continue to work correctly in a few days, i think that i will sneak inside to check the circuitry. I don't have a high voltage probe, but they probably use the inexpensive and common diodes/capacitors voltage multiplier method. By measuring the 1st stage's voltage(wich is under 1000V most of the time) and checking the number of diodes used, i'll be able to estimate the output voltages, both for the positive (collector band) and the negative (ions emitting points). Thanks again...i'll keep in touch within this thread.

-- Alain(alias:Kilowatt) Montréal Québec PS: 1000 excuses for errors or omissions, i'm a "pure" french canadian! :-) Come to visit me at:

Be sure to keep it clean! Maybe even an ordinary particulate filter in the room would help keep the dust from accumulating on the ionizer.

Have Fun! Rich

KILOWATT wrote: