way to check tha knock ?

[Tony Lum]

At 01:57 PM 12/13/2004, Denis wrote:
>Any way i can check the knock ?
>
>Ðenis
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The knock sensor is a piezo (crystal) microphone.  In other words 
vibrations distort crystal element which then generates a voltage.  IMHO, 
one way to check it is to use an oscilloscope (because piezo is high 
impedance) bolt the sensor to a block of metal and then tap the block with 
a hammer and observe if there's an output.  No BTDT, though and nobody's 
actually done it.

Tony