HOWTO build an Electronic UFO Detector

  Qepcmku0Hrw Tuic-Piwwoi Aaaaaaaaaju Oulhzcm8M80 S1600 Ufo Detector

From a 1968 issue of Flying Saucer Review is this HOWTO on building your own Electronic UFO Detector. It's actually an electronic magnetic field alarm, so even if you're skeptical about UFOs, this device could probably also be used to detect ghosts.
"1968 UFO Detector" (Strange Attractor)