"Electro-Static Air Filters"

Origionally Created: Jan 21, 2004

Latest Update: Dec, 9, 2011

Now this can operate on either 110 or 220 VAC.
If Ordering this, You MUST Specify Which Voltage you want.

These types of filters can be EXTREMELY Effective for removing Extremely Small Dust and Smoke Particles from the Air.

A vast majority of these Commerical Units that are on the market today are Crap.
Especially the ones used in Pubs and Bars which are: "Very Poorly Designed" with plates having a depth of about 3 inches.
But even Far Worse are Most of the Electrostatic Furnace Filters with plates only about 1 inch deep.

Additionally, "Ionic Filters" that don't use a Fan are Very "Inefficient" in Collecting Dust Particles. The plates on them are very small and even though they may appear to collect a lot of dust, the surface area is small, giving a false impression of the real amount collected. Additionally they only collect dust in there Immediate Vacinity and if there is is little or no real air flow in the room, it will do very little to clean all the air in a room.

The Basic principal of operation is to first charge the air flow either positive or negative, using a High Voltage Source of typically 4,000 to 6,000 Volts. Than past this air flow between sets of oppositely charged plates.
(Voltages greater than about 6,000 volts can create some Ozone, which can be harmful to a persons health and voltages less than 4,000 volts doesn't effectively charge the particles in the air.)

These positive and negative plates are alternately stacked as Positives and Negatives, about 0.2 inchs apart one on top of the other, so there is significent area for the volume of air to flow freely and at a relativel slow speed through the spaces between. As the air passes between these plates, all particles of matter will be Rejected from the Like charged plates and Attracted to the "Opposite charged plates".
This is simular in principal to rubbing a balloon on your hair which will than allow it to stick to a wall.

One Essential feature is to have the plates deep enough to allow for the rejection and attraction of the small particles. The other essential is to have a Relatively Slow Air Flow across each plate.
Both these design features give the particles more chance to attach themselves to the opposite charged plate.

A well designed filter will have plate with a depth of 5 inches Minimum. With as many stacked plates at your desired width to allow for a "gentle flow" across each one.

Pre-Filter: It is also a good idea to have a very simple screen filter, to catch "Larger particles of "Lint" as these can clog up an electrostatic filter quickly, but the electrostatic plates and Pre-Filter Screen, never need replacing, just a good washing from time to time.

About Paper Filters

Unlike all the paper filters such as "Hepa" and many others:
Electrostatic filters have very little resistance to air flow.

Also contrary to most persons who believe "Hepa" is a Specific Type of filter.
It Isn't!
It is a "Trade Name" and the "Hepa Company" make a range of filters that go from almost useless to really good. The really good ones are mainly used in the medical field and are Very Expensive.
Most household appliance paper filters Are NOT as good as people are led to believe.

IMPORTANT: Another thing most people Don't Understand is:
Unless the Polutant goes DIRECTLY into the Any Type of Filter System, it isn't immediately removed from the air.
It just gradually becomes less and less as the Air in the Room goes through the filter Over and Over Again.

Example: A person is smoking and blowing his smoke into the room, But NOT Directly into the filter.
Unless that smoke is blown DIRECTLY into the Filter, It takes a long time, Days, Even Weeks, to actually get it "Totally Filtered Out".

Until than, Your Breathing it!


Click here to see a Typical Good Designed Filter

Click here to see a Typical Filter Layout

Not too easy to see, but on either end are terminals, one end positive and the other negative.
These make contact with the High Voltage source.
The small wires running across the front that are attached to tension springs,
are there to charge the air positively, before it enters between the plates.

Click here, HV. Generator Schematic

Update, I can now supply the Trigger Coil:
I have now Obtained some more of these Isolated Trigger Transformers and have Tested them.

These will deliver about 6 KV output in this Circuit.

I Measured this voltage by connecting the output through a 100 K resistor into a .25 uF @ 10KV Oil filled Capacitor,
charging it and than measuring the output with a 25 KV Probe on my "Fluke Meter".
(You Can't Mesure the output Directly as Volt-Meters Draw More Current than the Trigger coil supplies.)

My Final Cost was $2.20 each US Funds, and I will also sell them at this price,
Plus the Postage Cost to mail them out.

I Can Supply Most of the Electronic Parts for this project.
But I do Not supply any Actual Filters or even the metal Plates for these filters.

These Transformers Measure aproximately 0.3 inches square by about 0.75 inches in Diameter
and are Vacuum potted in WAX.
They have 3 Terminals on the Bottom and the HV Terminal on the Top.

Click here, "REVISED" HV. Generator Picture OVERLAY.

Click here, for a PCB Layout

I was Given this "Honeywell", Electrostatic Filter.
This is the Type of Smoke Eaters, used on the ceilings of Bars and Pubs.
However Not used as much today as Smoking is now banned in many places.

Honeywell Supply from a Pub type "Smoke Eater"
As Many people call them.

The Output Voltage is 4.6 KV and the Circuit is Quite Complex and seems like a Real OVERKILL to me.

Honeywell Filter from a Pub type "Smoke Eater"
I Also tried this filter using My Electrostatic Supply and it worked very well.

Honeywell Filter from a Pub type "Smoke Eater"

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