wiki:projects:humidifier [Luca's project log]

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wiki:projects:humidifier

Air Humidifier

project
Category3dprinting
Statusin progress

Looking for an excuse to learn Fusion 360, I've started working on a humidifier project. It uses a standard piezoelectric driver from one-and-only Chinese shopping site and is meant to be printed in mostly a single piece. For the water reservoir, I've selected a IKEA carafe from their 365+ line. It's cheap and available globally.

Bill of materials

This is work in progress. BOM is subject to change, but the driver, PSU and carafe are here to stay.
Item Price
IKEA caraffe part no. 503.518.54 About 3$
Ultrasonic humidifier 6$
24V Power Supply 3$
40x40mm 5V fan 1$
Grey PET-G and TPU filament
???

Design

Body

My goal was to make a humidifier that wasn't an eyesore. After some drafts, I've decided to make a model of a power plant condensation chimney.

I fount a suitable photo, imported into Fusion 360 and traced a bezier curve along the edge. With an extra line running down the middle to act as the axis of rotation, and two perpendicular lines to make a plane, I used the revolve tool to make a 3D shape. Then the model was hollowed out using the shell tool. It was surprisingly easy.

Bottle

The first iteration of the project made a problem apparent - there needed to be a way to fill the bottle and insert it upside-down without spillage. Inserting the humidifier onto the bottle and then turning it just wasn't going to cut it.

To solve it, I've designed a bottle cap. When the bolt is pressed down it lifts the little cap and lets water flow out. Outer casing of the cap is printed in TPU to make seal, rest is PETG. A spring keeps the cap closed, even when full bottle is held upside-down. The valve is released when bottle is inserted into the humidifier body.

TODO: Bolt travel needs to be elongated, as it is now bubbles aren't able to enter when perfectly level and no water flows out.

Vapour production

Water vapour is produced using off-the-shelf piezoelectric transducer. Once powered, it applies voltage to a ceramic piezoelectric driver making it oscillate vertically, breaking the water into a fine mist. A good explanation of the working principles is available on Quora.

The upside of working with a ready-made transducer is the integrated water level sensor, so there's one thing off the list. Unfortunately, it also comes with some tacky LEDs that need to be dealt with. I'll probably cover them up, but I recommend getting a different transducer. I might prepare a second STL for the new transducer.

After covering the LEDs on the transducer, I'm planning to incorporate some amber/orange tasteful LEDs that will provide a bit of a "open core" glow for the fancy look points. They'll most likely be placed around the bottle at the base

A fan is needed to force the mist out, as it's heavier than air. To solve that I've modelled a fan into the bottom of the case that will blow air into the machine. In order to prevent water getting into the fan, the air duct is cane-shaped.

Electronics

I don't want a power switch on the outside of the device, so I'm thinking on placing a capacitive switch at the base. It's a work in progress.

  • Select a capacitive switch design that will work through couple millimetres of plastic
  • Either change the fan for a 24V or select/make a step-down converter for it
  • Maybe throw an ESP8266 into it and make it IOT because it's 2019

Luca Bernardi 2019/12/21 16:30

wiki/projects/humidifier.txt · Last modified: 2020/06/09 15:44 (external edit)