what is piezo

Escobon said:
True. I can add that most piezoelectric transducers are ceramic, which has a crystalline lattice structure. Physical stress on this element causes changes in conductivity. This can be sensed when a potential is applied to the piezo element. Changes in conductivity, and therefore current, can then be sensed and amplified by passive (reactive), or active circuitry.
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Disagree. All piezo systems I'm familiar with are based on crystals generating voltage whenever pressure is applied. AFAIK that's actually what piezoeffect is - charge appears when pressure is applied.
 
Shoewreck said:
Escobon said:
True. I can add that most piezoelectric transducers are ceramic, which has a crystalline lattice structure. Physical stress on this element causes changes in conductivity. This can be sensed when a potential is applied to the piezo element. Changes in conductivity, and therefore current, can then be sensed and amplified by passive (reactive), or active circuitry.
Click to expand...
Disagree. All piezo systems I'm familiar with are based on crystals generating voltage whenever pressure is applied. AFAIK that's actually what piezoeffect is - charge appears when pressure is applied.
Click to expand...

The charge develops when the lattice structure is stressed. At the atomic level, valence band electrons become conduction band (free) electrons at that point (yes, a quantum leap occurs), hence a charge (negative) builds up, and the surface of the piezo becomes more conductive. When the stress is removed, the piezo reassumes its intrinsic insulator properties.

From the piezo, the potential difference can be detected in more than one way. What I described is but one (common) way the changes can be sensed.

The phenomenon you are describing is called the 'direct piezoelectric effect'. Vibrations from the strings cause the stress, and therefore the changes in potential.

The 'converse piezoelectric effect' is exactly the opposite mechanism. Applying an electric field to the piezo causes physical vibrations in the ceramic. We see this phenomenon in the piezo tweeter.

I think we're basically saying the same thing here.

O
 
Escobon said:
I think we're basically saying the same thing here.
O
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Most likely we do. But I don't say anything about what happens inside the crystal. For me it's just a capacitor connected in series with a voltage source. :)
 
Escobon said:
The charge develops when the lattice structure is stressed. At the atomic level, valence band electrons become conduction band (free) electrons at that point (yes, a quantum leap occurs), hence a charge (negative) builds up, and the surface of the piezo becomes more conductive. When the stress is removed, the piezo reassumes its intrinsic insulator properties.

From the piezo, the potential difference can be detected in more than one way. What I described is but one (common) way the changes can be sensed.

The phenomenon you are describing is called the 'direct piezoelectric effect'. Vibrations from the strings cause the stress, and therefore the changes in potential.

The 'converse piezoelectric effect' is exactly the opposite mechanism. Applying an electric field to the piezo causes physical vibrations in the ceramic. We see this phenomenon in the piezo tweeter.
Click to expand...

Warp speed mr Zulu !!! 8)
 
For me it's just some fancy boutique addition to sweet basses that will generate some sweet sounds. I don't like to study and know everything about stuff. I like it to be a little mystical :)
 
Benjamin said:
For me it's just some fancy boutique addition to sweet basses that will generate some sweet sounds.
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Piezo pickup was the only pickup on my cheap starter bass for about a year (so it was the only pickup available to me).
 
`

It's a pressure transducer. When pressured, it induces trance :-b


Without getting technical but describing most piezos functionally,
AS INSTALLED, you could just consider them to be a contact mic.

Now if you know a whole lot about the "anatomy" of contact mics,
you will prolly want to argue this. But if you just USE contact mics,
then just consider any installed piezo to be a contact mic and its
function and tone will be pretty much what you expect.

Installation, EQ, and buffering can have a major impact on the
results [just like with regualr magnetic PU's], but I've got about
15 piezo basses on hand and in use, and despite their variety,
the "contact mic" concept is what they all have in common.

`
 
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