Learning about guitar and acoustic pickups and the physics and electronics behind them. I've heard that pyroelectric acoustic guitar pickups are nice? Looking and can't find anything.
You probably are hearing people say "piezoelectric pickup" because it is often erroneously pronounced "pie-zoh" instead of the correct "pee-ah-zoh".
Piezo (for short) pickups work by sensing vibrations. They are based around piezoelectric crystals which create electric potential (voltage) when they are flexed. They are used often for acoustic guitars because they pick up more the vibration of the top and body of the guitar versus a magnetic sound hole pickup, which works like an electric guitar magnetic pickup by inducing an electric current in the strings. Piezo pickups also work for nylon string guitars where magnetic pickups worn't work at all.
Piezo pickups are also popular for all kinds of other string instruments like violins and banjos, etc. And they are used for certain kinds of microphones. Some solid body electric guitars have piezo pickups build into their bridges to allow for a more acoustic sound from an electric guitar.
Piezo pickups have a crisp, often brittle sound, that can be musically appropriate but usually their sound quality is considered a downside of them. One very famous piezo pickup recording is the acoustic part of "Low" by Cracker from the 90s.
See also: https://en.wikipedia.org/wiki/Pickup_(music_technology)#Piezoelectric_pickups
+1 I would not have guessed that's what the OP meant haha. Good work! Piezoelectric energy is fascinating. I've piezo mics before, and when used WITH other mics, you can get some great clear sound. Never heard piezo pickups though. For certain instances, i'm sure it'd be great. Like if there are two or three guitarists, having one use piezo would really help with separation i bet.– user42882Nov 10, 2017 at 21:13
1@AytAyt - Piezoelectric energy is one of the many ways kinetic energy can be transformed into electrical energy. Piezoelectric Effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress. First Law of Thermodynamics: the total energy of an isolated system is constant; energy can be transformed from one form to another, but can be neither created nor destroyed Different materials convert or transform kinetic energy when it's applied to them. Piezoelectric materials do it by generating an electrical charge - very interesting indeed. Nov 10, 2017 at 23:47
A pyroelectric pickup would convert fire into electric signals. It would likely only make sense for rather exotic playing styles.
You are probably thinking about a piezoelectric pickup. Those convert mechanical vibrations into electrical signals and are typically located in the bridge. They are more typical for acoustical guitars (and semiacoustics) than for electrical guitar since the usual magnetic pickups on an electric guitar fit the expected style of sound better.
1A pyroelectric pickup would convert fire into electric signals... I read somewhere that Jimi Hendrix used them... Nov 10, 2017 at 23:42
Actually it wouldn't have to be fire. Just temperature changes. Nevertheless, it couldn't produce waves above 20Hz (which are audible and have a pitch) under normal circumstances. To control an oscillator with, that might be interesting though.– user43681Nov 12, 2017 at 7:57