What would you do with those old PIRs? I've made "Candle light" movement sensor.
The reason is simple - we are getting the cat soon and I was tasked to do something to see where I am going at night and did not step on the kitten :-)
Money can buy anything these days, security lights out of the box are non-expensive but so goes the fun away :-)
So instead of doing it an "easy way" and going to the warehouse - I've done it the "fun way":
1. PIR sensor from the decommissioned alarm
2. Mains to 12V adapter from whatever network system
3. MOSFET + 2 Diodes + 3Caps + 1 micro relay (or transistor equivalent could be used instead) - all from recycled power supplies
4. Empty canister from the Candle Light
5. 2 x 6V bulbs in series making 12V form the backlight of the car ODO.
End result - lights on for 15 seconds every time you walk:
If external relay is added - you can switch something else - some people were making "cat repellent" activating water sprinkles :-)