[Hallicrafters] Piezo

[Wilson Lamb]

I used dozens of ceramic piezoelectric xdcrs during my career.  The classic 
material was LZT, lead zirconate-titanate.  You'll see words like these in 
the nice writeup someone posted...very useful!

Every modern submarine has TONS of xdcrs covering its front end.  Generally 
highly classified, but the pictures of the sub that ran into a seamount a 
few years ago show some of them.

Then, a little way down
"  High-K ceramic capacitors can show significant piezoelectric effects; if 
you tap them they will produce a voltage spike.  This is caused by the 
barium titanate, the main material in high K ceramics.  The higher the K, 
the stronger this affect.  This can cause problems with circuitry dealing 
with low-level signals, making them vulnerable to mechanical shock.  "

Maybe this topic can rest now?

BTW, the ceramic xdcrs are many times more sensitive than quartz.
73,
WL