Challenge: design a water cannon for deterring cats
I'd like to improve the odds of survival for all the birds, amphibians and small mammals in my garden, but without causing physical harm to the cats. I've tried scent-based cat repellents without success, and I completely reject the idea of indiscriminate noise scarers. I can't police the garden 24/7, so my preferred solution is a water cannon capable of detecting a cat and soaking it.
To keep things simple, I'd be thinking of using mains pressure to power the water jet, and batteries to power a motion sensor (infra-red). To be useful, the design would need to:
- hit targets within a user-specified arc and at varying distances
- allow the user to configure the sensitivity of the sensor, so that cat-sized heat sources are treated as targets, but smaller mammals are non-targets
- avoid being triggered by foliage disturbed by the wind.
For extra credit, the design could:
- use solar power instead of batteries
- focus the jet at the target, rather than spraying mist over a large area