Deodshiot

A Light Triggered Air Freshener

This project was heavily inspired by James Callaghan’s project: Can you IoT an Airwick air freshener?

The default behaviour of this device before you tweak it is to spray once every 15mn. This is wasteful and inconvenient.

I wanted to have the Air Freshener triggered every time I leave the restroom, when I switch the light off. Depending on the sliding switch position, it will spray more or less often:

• ❚ : Off
• ● : Will spray once every 30mn at most, if light was on during at least 5mn.
• ● ● : Will spray once every 5mn at most, if light was on during at least 3mn.
• ● ● ● : Will spray once every 30s at most, if light was on during at least 5s.

I also wanted everything to fit in and to use the default AA batteries.

There are two versions:

• Deodshiot, using a 3V3 Arduino Pro Mini
• DeodshiotIOT, using a NodeMCU / ESP-8266 / LOLIN (WEMOS) D1 mini connecting to a ThingsBoard server, so that you may monitor how long you are spending there and make statistics out of it…

Todo: Test with a MQ-136 gas sensor if the Air Freshener can be triggered when it smells bad.

Parts List

You will need:

• 2 pieces of bakelite testing plate (0.1in/2.54mm, 6x8 and 6x15)
• 2 resistors ~1KΩ
• 1 photoresistor
• 1 PNP transistor (PN2222 or equivalent)
• 1 diode (1N4007 or equivalent)
• 1 relay (JRC-23F or equivalent)
• 1 microcontroller (Arduino Pro Mini or equivalent / LOLIN WEMOS D1 mini or equivalent for the IOT version)

The build

There is nothing complicated as long as you are cautious.

Have a close look at the schematics and pictures below to see how things work.

• Flash your microcontroller with the suitable program.
• Remove the top cover.
• Remove the 4 screws (you need a long - 4cm long minimum - Philips ⨁ screwdriver).
• Remove the block out of Air Freshener.
• Push gently the part with the motor away from the rest (so that the axes are out), then up.
• Remove the circuit board.
• Un-solder the sliding switch and the two battery connectors. (NB: You need to bend the sliding swicth pins so that they can fit into the 0.1in/2.54mm testing plate.)
• Cut the 2 bakelite testing plates, solder all the components.
• Drill one hole so that the wires can go through.
• Solder the wires to the bakelite testing plates, microcontroller an motor. Double check that the motor turns the right way.
• Put everything back in place.
• Drill one hole in the top cover so that the photoresitor can see the ambiant light.

Schematics

Schematic is very classic.

• 1 digital output controls the motor. We use a transistor and a relay to avoid frying the microcontroller.
• 1 analog input reads value from the photoresistor.
• 2 digital inputs read value from the sliding switch (position ● / ● ● / ● ● ●). We use the embedded pullup resistors (INPUT_PULLUP).

Arduino version

IOT version

Bakelite testing plates

First one

Second one

Project pictures

Reading measurements

You may use Arduino Serial Plotter to check if everything is working as intended.