Shop OBEX P1 Docs P2 Docs Learn Events
pizo vibra film tab's. — Parallax Forums

pizo vibra film tab's.

stamp_demonstamp_demon Posts: 69
edited 2005-06-26 00:14 in BASIC Stamp
Hello, I ordered a few of the pizo vibra film sensors. I was wondering wich lead is possitive, and wich is negitive. Or does it not matter?? Also if I can't find the 5.1 v zenor diod is there a possible subsitition?? Thanx _Duane

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-06-25 21:20
    Hello,

    ·· The Piezo Vibra tabs don't really have a polarity, per se.· No negative or positive lead.· As for the 5.1V Zener Diodes, Parallax carries them and there is a link on the product page for them.· The Zener Diode is recommended but not absolutely necessary.· The device outputs up to 70V under certain conditions, and a Zener Diode clamps that down.

    ·· The current, however, is extremely low, and shouldn't damage a Stamp I/O pin.· I prefer to use the Zener in conjunction with a 220 ohm resistor (Just to be on the safe side), although you could use an op-amp, or even I 1MOhm or 10Mohm resistor with a small capacitor.· The device really has several characteristics that lend well to other applications if you understand it.

    ·· One example I tried was using an Op-Amp to amplify the signal (And buffer/filter the output) so that I could read air movement, such as breathing on the device.· If you have a scope and set your volts/div down to 500mV or less you will see what I mean.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • stamp_demonstamp_demon Posts: 69
    edited 2005-06-25 23:05
    I had planned on ordering a few diods latter... It was my mistake; I didn't see that I needed them untill after they arrived. So I ws thinking about ordering them with my next order; in a few weeks. I might try using a 10 meg ristor.. What size cap were you thinking of ??·A 0.1 uf perhaps?·
    · Thanks again _Duane
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-06-26 00:14
    Duane,

    ·· Those other components values really depend on the application and the way you're using the part.· For now, I would just tie one end to ground, and the other through a 220 ohm resistor to the Stamp I/O pin.· Any movement on the tab (Bending/Flicking) should result in the I/O pin seeing a HIGH.· I would still get the Zener though, but you could mess around with it for now.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
Sign In or Register to comment.