Introduction: Room Air Purifier

I made this device mainly to counter 2 main problems that I had:

  1. Air purification in my room
  2. Cost of Air purifiers that clean air

This made me search for alternatives for tackling the same problem but with a lot cheaper solution. So I thought of a not so conventional method of trying to capture particles and luckily found out on the internet that there was research and work done for the same that is, capturing particles by the use of negative ion.

There were negative ion generators available but none was trying to capture it systematically like a device or a machine. So I thought why not combine these two and try to make a cheap and wholesome air purifying equipment.

With further research, I came to know that negative ions ( arguably) have lots of positive benefits as well which made me even more fixated on going forward with the approach that I had in my mind.

Also, this is my first attempt at soldering anything so please excuse the untidy soldering work.

Benefits of negative ions supposedly include:

• freshen and purify the air

• help lift the mood

• alleviate depression including winter depression(SAD)

• eliminate most tiny particles suspended in the air (indoors)


You'll be dealing with extremely high voltage here so necessary precautions should be taken which I'll list later on in the step by step guide.

Step 1: Materials Required

Working Equipments:

  • Soldering iron and solder wire
  • hot glue gun
  • 3 pin socket (if you have earthing available) / 1metre 3 core 220v ac lead
  • wire pieces
  • wire cutter
  • multimeter

Circuit components: (11 stages)

  • PCB (acrylic preffered)
  • 20 x 1mega ohm resistors. (limit output current for safety) or 2 x 10 megaohm (whatever is available)
  • 44 x diode 1N4007
  • 33 x capacitor 100nF 275V class x2 suppression.
  • standard pins for high voltage grid.

Casing Components:

  • 4 acrylic sheets for body or anything that solid enough
  • Glue
  • 2 fans with sufficient suction capacity ( use them as per your desired noise levels by reducing the supply voltage to them. This will obviously result in efficiency change but that's a trade you gotta make.)
  • 1 mesh filter ( not too dense )
  • DC supply for fans via battery
  • Double sided tape as well as normal tape (or) clamps ( I used tape here in order to be able to open it for demonstration purposes).

Optional tool (recommended) :

  • wire wrapper. ( I hurt my fingers badly wrapping those ends lol)

Step 2: Understanding the Circuit

Walton Cockroft Voltage Multiplier

Step 3: Circuit Schematic Diagram

This is a full wave rectifier circuit.

Use this as a guide while placing components on the PCB

Step 4: Making the Circuit

  1. Place the capacitor and diodes stage wise.
  2. Solder them.
  3. Then solder the resistors in series like I have if you have only 1 megaohm ones available by the output of the Walton Cockroft multiplier circuit which you just made
  4. Then take naked copper wire, insert pins to it and solder them in position.
  5. Solder this part to the output for the series of resistors.

Optional but highly recommended step:

  1. Use multimeter after every stage to check if the diodes are working or not.
  2. Also, plug in the circuit after every stage is increased to check whether the circuit is functioning as desired or not. ( use multimeter by placing one point of it in the center line and the other at input)


Don't forget to discharge the capacitors after every use as mentioned earlier as well!

Repeat the discharging process twice or maybe thrice to ensure safety.

If possible, use rubber gloves while working to eliminate the possibility of getting shocks.

Step 5: How to Discharge the Circuit

Use a metal object to do it.

I used a cutter for this purpose since it's efficient at doing the job.

Step 6: Making the Casing:

  • Use acrylic sheets to create the structure
  • From cardboard (as per your dimensional requirements) create a body for the filter as well as for the fans
  • Place the fan as close to the filter as possible for maximum suction capability.
  • Create a nozzle type geometry out of cardboard on the section above filter for the air to be directed towards the filter.

Step 7: Assembly:

  • Join all the pieces via using the glue gun and also provide a protective casing for the circuit which has been attached on the outer side of the body
  • Place the nerve ending(pins) at the top of the body so that it ejects electrons in an upward direction.

Step 8: Working

This is the result obtained after switching ON the circuit for 25 ins in my less than average polluted room ( because I live in India if it's abroad you need to put it in areas of high pollution or generate pollution to test it which I can avoid since am in India lol).

You can see deposition on the needles if you zoom in.

If kept ON for prolonged time, the particles will get deposited on the needles as well as the area around it.

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