Last weekend our cat died. A car didn't see him and bang our little 1 year old kitten died. I couldn't blame the driver. It was dusk and cats are then barely visible.
Now I thought of the LED collars we have for our dogs. When we take the dogs walking for their piss before they go to bed we press a button on the collar and the LED's light up.
So I thought, what if I made a LED collar for a cat. The problem is, cats don't come home before dusk and say: "Hey, press the button to make me a shining cat". They just keep messing around in the neighbourhood until they decided to call it a day.
I think I could fix this problem with a light resistor. It detects when it's dark and plop lights go on, problem solved.
Next problem: "Battery consumption", in case the cat stays outside all night hunting down innocent mouse the lights will light all the night. I dont want to replace the battery every day so in perfect circumstances the LED's only light up when the collar detects a car approaching.
So my question for you: Is it possible to create a sound recognition for an approaching car? It doesn't have to be prefect offcourse. In the worst case: No sound at all -> lights off. Any sound -> lights on.