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do u know any piezoelectric sensor
to measure pressure
i can use with arduino?
thanks
emanuele bari italy
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No piezo sensor can measure static pressure, piezo sensors only output voltages proportional to change (well more precisely they output charge proportional to the signal, but leakage current eventually reduces the signal to zero again when the input is static).

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  I once attempted to use a piezo buzzer element (Radio Shack) as a pressure sensor.
  I used a TL082 op-amp (also Radio Shack ...super high input "resistance") to avoid loading the voltage appearing across the the crystal. When I added pressure from a finger, the voltage leaped to about 9 volts and took about 5 secs to fall (as long as I maintained pressure). As long as you pedal quickly enough (faster than 1 Hz.) you should be OK.
  What you need to watch out for electronically is what happens after you release pressure on the crystal. When it rebounds to a no load position, the voltage will be pulled LOWER than ground. You'll need to reset the piezo after you read it (on the upstroke somehow ... analog switch to ground maybe?) so the crystal starts at 0 volts on the next pedal downstroke.
  Mechanically, what are you going to do so you don't fracture the crystal? It won't bend much without breaking ... Google "wiki "load cell" " for some hints!
Good Luck, watch out for traffic!
 
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