from Hacker News

Build an Ioniser in Under $10

by sthottingal on 12/29/19, 5:10 AM with 39 comments

  • by Someone1234 on 12/29/19, 6:50 AM

    Just be cautious, while correctly working Air Ionisers are safe, poorly working or designed ones can produce Ozone which is unsafe (particularly over prolonged periods or high exposures). This article has more information (in particular citation 10 used in Adverse health effects):

    https://en.wikipedia.org/wiki/Air_ioniser#Adverse_health_eff...

    Personally I don't see the benefit over a HEPA filter on a standard electrical fan, or a commercial unit with a similar design. Yes, replacing filters is annoying/has a cost, but there's no health downsides to the design and it is effective at removing air particulate. Building one requires an off the shelf HEPA filter, an off the shelf fan, and a couple of rubber bands. It isn't "sexy" or technically sophisticated, but it works. Want it improve effectiveness? Increase the surface area/make it bigger/increase the airflow.

    Let's also consider what both devices (when working correctly) do. An Ioniser gives particulate a charge causing it to be attracted to and stick on surfaces. A HEPA traps particulate within a filter membrane. Or to phase that differently an Ioniser causes the particulate to dust onto every surface within range, causing dirt buildup/stains, dust blooms when disturbs, and people may still contact the air contaminants (since they still exist, now on surface rather than in the air). HEPA allows you to simply remove the particulate from the environment, Ionisers just move it from one location (air) to another (surface).

  • by amluto on 12/29/19, 8:40 AM

    As the former owner of a biggish HVAC-integrated electrostatic precipitator, these things are not really worthwhile. An ESP needs frequent cleaning to work well, in comparison to a plain old MERV 13 or so filter, which will work for quite a while with no maintenance.

    An ionizer doesn’t need maintenance, but that’s because it deposits all the gunk nearby. Eww.

  • by m0xte on 12/29/19, 10:09 AM

    Please don’t build this. There are numerous ways to kill yourself with it. Especially the construction as described.

  • by userbinator on 12/29/19, 6:14 AM

    The article mentions BigClive, and his YouTube channel does have a lot of stuff about ionisers, but his site has an article about them too: http://www.bigclive.com/ioniser.htm

  • by joecool1029 on 12/29/19, 5:49 AM

  • by ncmncm on 12/29/19, 7:12 AM

    He talks about carbon-fiber stuff to get lots of ionization points, but steel wool works great.

    You will be able to smell if you are producing ozone, which you don't want unless you like permanent lung damage. The smell is sharp. like around electric sparks. If you get that, the voltage is too high. Just leave off a few voltage stages.

  • by jvanderbot on 12/29/19, 1:03 PM

    All comments seem to recommend a good old filter over an ionizer. Would an ionizer in series with a filter (e.g. in air ducts ) be more effective than a filter itself?

  • by fortran77 on 12/29/19, 2:11 PM

    It is not healthy to breathe in high concentrations of ozone. It's difficult to make an "ionizer" that doesn't generate ozone.

    Also, the health claims of ionizers are dubious. False claims about them (and ozone) bankrupted The Sharper Image

    https://www.nytimes.com/2008/02/21/business/21sharper.html

  • by amelius on 12/29/19, 5:12 PM

    > I these days use LCSC.com to buy all my generic parts. Great selection at a great price. It’s way cheaper than Digikey or Mouser.

    That's a good one, thanks!

  • by eeZah7Ux on 12/29/19, 2:22 PM

    You can buy a ionizer for less than $10 on aliexpress and it might be less electrically dangerous.

    However - DON'T DO IT. Many ionizers generate ozone which is unhealthy.

    Also if the goal was merely to combat dust settling on the floor (rather that health), it will only make the problem worse.

  • by Tempest1981 on 12/29/19, 5:17 PM

    An estimated power use of 4 kWh per year -- only costs 4 Rupees in Mumbai? (around $0.05 USD) That's surprisingly cheap power. The US average is 10x higher. ($0.13/kWh)

    Still a small cost ($0.52/yr in the US)

  • by tomaszs on 12/29/19, 8:59 PM

    Epic

  • by willis936 on 12/29/19, 11:42 AM

    $10 really means ripping apart and wiring up cheap Chinese consumer electronics. A PCB project is at minimum $100.