If you have a cat you have a litter box. If you have a litter box you have dust. This Instructable shows how I made a litter dust collector that uses a common fan and filter and some easily available electronics.
The idea is to detect my cat at the litter box and turn on a fan, drawing dust into a filter, for a few minutes.
See the block diagram image.
You will need:
- Box fan ($20)
- Furnace Filter, 20x20x1 ($5)
- Arduino Uno/clone & USB Cable for programming ($10)
- 9V DC Power Adapter ($5)
- HC-SR04 Ultrasonic Detector ($2)
- KY-019 Relay Module ($5)
- Mini Solderless Breadboard ($1)
- Hook up wires
- Extension cord ($2)
- Scrap plywood, any thickness, 6" square
- #4 x 1/2" screws
- #6 x 3/4" screws
- Cable Ties & Staples
Step 1: Box Fan and Furnace Filter
Get one of those 20-inch square box fans. If you're lucky you have one lying around. These have been around for years and used to be as cheap as $10, but now they're more like $20. The furnace filter is a 20×20×1 (inches), which is a common size. I got the basic one for $5. You can get more expensive filters, but I expect I'll need to change them fairly frequently.
I used duct tape to hold the filter on. There appears to be no space for leaks, so all the air should move through the filter.
Step 2: Gather the Electronics
An Arduino Uno clone is the microcontroller. You can get these for as little as $10 with the USB cable. To detect my cat I am using the HC-SR04 ultrasonic detector. And to control the fan I am using a 5V relay module. I laid-out the modules on a scrap piece of plywood about 6" square. I also used jumper wires, which is okay for a temporary connection. I may solder everything; I may not.
The relay normally open (NO) contacts switch the HOT line from the mains. This is important for safety. Once these are crimped into the relay connections, use an electrical staple to keep them from moving around. Note you have to cut the HOT wire of the fan's cord, so decide if you really want to do this project before cutting. And I should not need to say it but here goes: DO NOT cut the cord when it is plugged in.
Step 3: Software
You can find the software here. Let me know in the comments if you can't view this.