Identifying the Odd Electronic Component

If you ever come across an electronic component that looks like this (a small electrolytic capacitor or radial inductor) with simply the letters “HDX” and rattles if you shake it (even a little bit) then I’ll save you some trouble.  It’s called a “vibration switch”!  And, as you might guess, it’s a SPST switch that closes it’s contacts when it senses vibration.  These are not as sensitive as a G-Force sensor but they can do the trick in telling something when it’s being picked up or moved around.