[PD-ot] piezo-electric sensors

Enrique Tomas warholiano at yahoo.es
Tue Jan 8 23:13:10 CET 2008


Hi
try putting a 1 MOhm resistor (at least) between your analog input and ground. It tends to discharge the energy and it also adapts the input-output impedance (that it's really diferent). 

it also helps to put a simple RC low pass filter centered at 300Hz (more or less). If you can see the piezo signal in time you will discover a sinusoid multiplied by a negative exponential. Try to filter the signal and you will get the envelope (the peak). 

good luck!
Qq

----- Mensaje original ----
De: Patrice Colet <pat at mamalala.org>
Para: pd-ot at iem.at
Enviado: martes, 8 de enero, 2008 15:54:53
Asunto: [PD-ot] piezo-electric sensors

  Hello, I'm trying to build a system for getting impulses from
 bouncing 
balls on a medium board, for driving sounds or a step sequencer.

  The cheapest solution was about using a piezo-electric disc, that 
transform the mecanic impulsion into electrical energy. So I use the 
analog input of the Arduino interface for receiving this energy amount,
 
and then I just have to choose a threshold level of the released
 energy, 
for triggering into PureData.

  But the problem I'm encountering is that the electrical circuit made 
by the piezo probe and the arduino, with no other additionnal component
 
has a too high capacitance, so the energy level is lowering too slowly 
after each mecanical impulsion, then my system doesn't trig anymore 
until the circuit capacitance goes below the threshold level set in 
PureData.

  There certainly is an electronical trick for discharging the energy 
just after each impulse, maybe someone that read this message has 
sufficient skills in electronics to help?

  Thanks,

pk.

_______________________________________________
PD-ot mailing list
PD-ot at iem.at
http://lists.puredata.info/listinfo/pd-ot






       
______________________________________________ 
Web Revelación Yahoo! 2007:
Premio Favorita del Público. 
http://es.promotions.yahoo.com/revelacion2007/favoritos/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.puredata.info/pipermail/pd-ot/attachments/20080108/e537a638/attachment.htm 


More information about the PD-ot mailing list