Here’s a simple electronics project we can all approve of: The Electronic UFO Detector, from a 1968 edition of the then-highly-respected British journal of ufology, Flying Saucer Review.
The device is actually a magnetic field detector. While the case for UFOs producing strong magnetic fields is not exactly cut and dried, magnetic anomalies do appear to have been detected in at least some cases over the years.
Magnetic anomalies do seem to be associated with earthquakes [see this paper from the Journal of the Society for Scientific Exploration for example] and so, perhaps, with the UFO-like lights sometimes linked to them.
Even if it won’t help you spot UFOs , this would be a fun paranormal project and it might help you to detect a quake, or perhaps even a ghost.
Via the excellent Forteana blog