
Build an Ioniser in Under $10 - sthottingal
http://amaldev.blog/build-ioniser-in-under-10-dollars/
======
Someone1234
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...](https://en.wikipedia.org/wiki/Air_ioniser#Adverse_health_effects)

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).

~~~
seltzered_
Veritasium had a good video showing the test of ozone being produced by air
ionisers: [https://youtu.be/ZQ--scjcAZ4?t=663](https://youtu.be/ZQ--
scjcAZ4?t=663)

(time-linking since the ioniser part was sortof hidden within a video
debunking himalayan salt lamps)

~~~
pergadad
Thank you, really enlightening video. I'm happy I bought a HEPA filter now,
rather than an ioniser.

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amluto
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.

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m0xte
Please don’t build this. There are numerous ways to kill yourself with it.
Especially the construction as described.

~~~
hydgu
Could you elaborate a bit more? I am curious from the technical side.

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m0xte
Lap soldered mains connection (can break off easily). Not double insulated
(think small children and fingers). Also the actual ioniser port is usually
recessed to avoid accidental contact as it hurts if you touch it.

Also lots of hand soldered MLCC caps are high potentials. They like to crack
and explode if you do that. They need to be machine soldered really.

Edit: also the design doesn’t use proper voltage rated resistors on the
output. I haven’t checked the other parts but it’s probably marginal. You’ll
get home one day and find your house burned down.

~~~
chadcmulligan
could do with a fuse to.

Those needles connected to active make me uncomfortable, though there's a 10M
resistor, I'd have an isolating transformer on the mains - not an engineer
though.

~~~
m0xte
Fuse would be good. Here in UK there’s one in the plug. The 10M resistor will
current limit. Or probably flash over here.

Isolation transformer is not required if the enclosure is better. It also
doesn’t help you if you stick yourself across it somewhere, only helping
yourself with respect to ground. If you’re testing it or doing development
with it I would use one. But I wouldn’t build it.

I used to hang around inside old valve radios when I was a kid. You learn
respect for high voltages very quickly.

~~~
dev_000
Hey you guys, Author of the article here. Thanks for mentioning the issues. I
never meant it to go this viral. Crashed my website in the morning. You seem
to mention that the output resistor was wrongly chosen. Can you elaborate? I
thought I designed it properly. This post was not ever meant to be used
without using basic safety features in mind. (Like keep it away from children
and all). I will explicitly mention that to be taken care of in the post.
Happy to take any more constructive criticisms to make the post better.

~~~
m0xte
Yeah no worries. We’re all hyper critical. Need to outline the dangers because
people who are unaware of the issues working with mains tend to be the first
to drop dead. This is followed by the people who suffer from Dunning-Kruger
effect. Us amateur radio operators like to kill ourselves on vintage power
amplifiers doing that.

The output resistor need to handle potential to ground so say 7kv across
output to ground. Resistor is rated for 200V working voltage. Usually you use
a chain of many smaller resistors here.

I haven’t reviewed the design entirely but the main problem is the enclosure
and mains connection and the component choice. The mains connection should be
clamped in the enclosure and either spade connections or screw terminals or
ferrules. The enclosure should be double insulated. As mentioned a fuse would
be a good idea as well.

Always design for worst case with these things.

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userbinator
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](http://www.bigclive.com/ioniser.htm)

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joecool1029
[http://web.archive.org/web/20191229051555/http://amaldev.blo...](http://web.archive.org/web/20191229051555/http://amaldev.blog/build-
ioniser-in-under-10-dollars/)

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ncmncm
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.

~~~
pbhjpbhj
I love the smell of ozone though (not kidding!).

I think it's an association from dicking around with dodgy electric motors
(that sparked in a cool way) when I was younger.

~~~
ncmncm
It's the same reason people like Lisp: it smells of youth.

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jvanderbot
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?

~~~
h2odragon
For some uses. I have to recommend the commercial Honeywell units highly:
they're excellent at pulling tobacco smoke and smell out of the air; and yes
the area around them will catch all the other dust around too.

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fortran77
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](https://www.nytimes.com/2008/02/21/business/21sharper.html)

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amelius
> 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!

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eeZah7Ux
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.

~~~
Tempest1981
During crop-burning season in India, when the air is hazardous, would an
ionizer + ozone be a net positive?

Crop burn pics: [https://www.theguardian.com/world/2019/nov/08/indian-
farmers...](https://www.theguardian.com/world/2019/nov/08/indian-farmers-have-
no-choice-but-to-burn-stubble-and-break-the-law)

~~~
pbhjpbhj
Interesting, we banned it in the early 90s in the UK (I used to love watching
it).

[https://www.eurekalert.org/pub_releases/2019-08/imaw-
atb0807...](https://www.eurekalert.org/pub_releases/2019-08/imaw-
atb080719.php) suggests there are better alternatives that will yield better
returns for the farmers; but I gather some UK farmers want to return to
burning as it - in their eyes - reduces weeds and provides ash for tilling in
to the soil. It's not a simply equation though, eg
[https://www.researchgate.net/publication/230319729_The_effec...](https://www.researchgate.net/publication/230319729_The_effects_of_stubble_burning_and_tillage_on_soil_carbon_sequestration_and_crop_productivity_in_Southeastern_Australia).

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Tempest1981
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)

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tomaszs
Epic

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willis936
$10 really means ripping apart and wiring up cheap Chinese consumer
electronics. A PCB project is at minimum $100.

