Detect those pesky kids before they get to the front door. Put it outside to spook the Trick-or Treaters as they walk up to your door. This project is motion activated using a PIR sensor, upon activating the Owl and some cheap LED string lights turn on.
Step 1. Prototyping
I built the circuit on a breadboard to test the idea. I used the PIR sensor and breadboard from the brilliant CamJam EduKit 2. I used transistors to drive the LED’s as the Raspberry Pi GPIO pins cannot supply a lot of current. The code was written in Python using the great GPIO Zero API. I set the Python script to load on start-up.
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| Breadboard layout |
GPIO Connections
GPIO 4 - PIR sensor
GPIO 5 - Owl via driver transistor
GPIO 6 - Bat lights via driver transistor
GPIO 12 - Hand lights via driver transistor
GPIO 17 - Shutdown switch
Step 2. Transferring the circuit onto a PCB
The circuit worked well so I decided to transfer the breadboard prototype onto a more permanent Adafruit Perma-Proto HAT.
Step 3. Building into an enclosure
While looking for suitable enclosures in Poundland I came across a nice plastic pot full of Halloween sweets, having removed the sweets to eat later. I set about cutting some holes in the pot for the PIR sensor and 3.5mm mono jacks. I connected all of the cables and checked that it worked.
Parts List:
1 x Raspberry Pi board, any model will work
3 x NPN Transistors
3 x 10KΩ Resistors
3 x Suitable resistors for the LED’s ( I used 22Ω resistors)
1 x PIR Infrared Motion Sensor (HC-SR501)
1 x PCB tactile switch
3 x 2 way Molex KK type 2.54mm headers and housing
1 x 3 way Molex KK type 2.54mm headers and 2 housings