Air Scrubber

thingiverse

Human: A budget-friendly USB-powered air scrubber, aka a straightforward air purifier. It continuously circulates indoor air through a HEPA filter, which cleans the air of dust and particles. ## Bill of materials - 12V 80mm Fan: Noctua NF-R8-1800 (Get this particular model. It is low noise.) - A cylindrical HEPA filter. - Dimensions of my filter: 123mm tall, 107mm outer diameter, 71.2mm inner diameter. Bought at "Biltema" in Norway: https://www.biltema.no/hjem/innredning/peistilbehor/filter-til-askesuger-2000043226 - Micro USB breakout board: https://ebay.us/2XpoFR - MT3608 DC-DC boost converter: https://ebay.us/rZmGOk The Fusion 360 project file is attached. If you are unable to source the exact same HEPA filter i am using, it should be enough to get a similar one, and update the "filterId" parameter in the Fusion 360 project to the measured inner diameter of your filter. I recommend getting the exact same fan, usb breakout board, and boost converter as listed. Everything has been designed to fit exactly, and I'm taking advantage of some plastic protrusions on the fan to hold the micro USB board in place. ## Electronics The device is powered by micro-usb, which provides 5 volts. A boost converter "boosts" this voltage to 12V, to power the fan. The boost converter is adjustable, so you can decide if you want to run the fan at a slightly lower voltage, for lower noise. You'll have to use short and thin wires for this project; space for electronics around the fan is limited. ## Wiring 1. Solder the + and GND pins from the usb breakout board, to the input pins on the DC-DC boost converter. 2. Power the circuit and measure the output voltage from the boost converter. It might be pre-set to 14-20 volts from the factory, and that could damage the fan if you hook it up without checking. 3. Adjust the little screw on the DC-DC converter so the output voltage is about 10-12V. It will be possible to adjust this later. The case contains a small hole that will let you adjust the screw even after fully assembling the air scrubber. 4. Cut to length and solder the fan wires to the output of the boost converter. Red wire from the fan to the + pad on the converter, black wire from the fan to the - pad on the converter.