If you have a raft in body of water, it can be relaxing and fun to hang out on. One aspect that is not fun is when birds also decide that it looks like a good place to rest and defecate on the surface as they please. MN Maker’s mom has one of these rafts, and after trying multiple methods to keep the birds off with no success, he decided to take things up a notch and create a device to make the bird’s raft experience less than pleasant.
What he came up with is a repeller that uses a motor to spin a pair of stainless steel rods around and push the birds on the raft away. While it spins slowly enough that it’s unlikely to hurt any woodland creatures, it would certainly make it a less fun place for them to congregate… and do their business. The build uses an ATtiny85 for control, along with a RTC module to only spin it from around 8:00 AM to 6:00 PM at a set interval. The unit is solar-powered, and this intermittent operation would save energy when not needed. Presumably the birds go somewhere else at night.
Another clever feature of the repeller is that it’s attached to its own little raft. When humans want to use it, they can then throw the spinner overboard and enjoy the surface, replacing it when needed to keep everything poop-free.