<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:arial,helvetica,sans-serif;font-size:10pt"><div style="font-family: arial,helvetica,sans-serif; font-size: 10pt;">Hi<br>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). <br><br>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). <br><br>good luck!<br>Qq<br><br><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;">----- Mensaje original ----<br>De: Patrice Colet <pat@mamalala.org><br>Para: pd-ot@iem.at<br>Enviado: martes, 8 de enero, 2008 15:54:53<br>Asunto: [PD-ot] piezo-electric
sensors<br><br> Hello, I'm trying to build a system for getting impulses from
bouncing <br>balls on a medium board, for driving sounds or a step sequencer.<br><br> The cheapest solution was about using a piezo-electric disc, that <br>transform the mecanic impulsion into electrical energy. So I use the <br>analog input of the Arduino interface for receiving this energy amount,
<br>and then I just have to choose a threshold level of the released
energy, <br>for triggering into PureData.<br><br> But the problem I'm encountering is that the electrical circuit made <br>by the piezo probe and the arduino, with no other additionnal component
<br>has a too high capacitance, so the energy level is lowering too slowly <br>after each mecanical impulsion, then my system doesn't trig anymore <br>until the circuit capacitance goes below the threshold level set in <br>PureData.<br><br> There certainly is an electronical trick for discharging the energy <br>just after each impulse, maybe someone that read this message has <br>sufficient skills in electronics to help?<br><br> Thanks,<br><br>pk.<br><br>_______________________________________________<br>PD-ot mailing list<br><a ymailto="mailto:PD-ot@iem.at" href="mailto:PD-ot@iem.at">PD-ot@iem.at</a><br><a href="http://lists.puredata.info/listinfo/pd-ot" target="_blank">http://lists.puredata.info/listinfo/pd-ot</a><br></div><br></div></div><br>
<hr size=1><br><font face="Verdana" size="-2">Web Revelación Yahoo! 2007:<br> Premio Favorita del Público - <a href="http://es.promotions.yahoo.com/revelacion2007/favoritos/">¡Vota tu preferida!</a></font></body></html>