I don't remember offhand; it was just a generic off-the-shelf 120VAC motion sensor from the hardware store, the type used to turn on your bathroom lights when you walk in. It controlled the power supply to the rest of the electronics. Really minimal stuff. If I recall correctly, my oscillators...
I've done several things. First, cover the countertops with aluminum foil. You can always use it for other purposes later. That scares the bedgeezus out of them when they land on it.
For more pressing cats, I've laid out adhesive tape (do NOT use duct tape!) like blue painter's tape, sticky side...