The new Piezoelectric vibration sensor
LoopyByteloose
Posts: 12,537
It seems to have a polarity, but the Parallax PDF doesn't acknowlege the fact.
Since it says that it can put out a hefty 70 volts if really shook and safe reverse volt threshold is likely less than -1.0 volt before damage occurs [noparse][[/noparse]usually -0.5volts], someone might want to correctly identify this.
Personally, I am seriously thinking of buffering it with a voltage divider, a transistor or a 74hc07.· I know the 5.1volt Zener should do·the trick·on its own, but a bad connection on the breadboard and you might need a new BasicStamp.
Nonetheless I am very excited about using this to sense water flow in a pipe.· Seems I could just attach it to the outside and pick up enough vibes to trigger it.
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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)
······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
Post Edited (Kramer) : 12/14/2005 5:23:26 PM GMT
Since it says that it can put out a hefty 70 volts if really shook and safe reverse volt threshold is likely less than -1.0 volt before damage occurs [noparse][[/noparse]usually -0.5volts], someone might want to correctly identify this.
Personally, I am seriously thinking of buffering it with a voltage divider, a transistor or a 74hc07.· I know the 5.1volt Zener should do·the trick·on its own, but a bad connection on the breadboard and you might need a new BasicStamp.
Nonetheless I am very excited about using this to sense water flow in a pipe.· Seems I could just attach it to the outside and pick up enough vibes to trigger it.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)
······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
Post Edited (Kramer) : 12/14/2005 5:23:26 PM GMT
Comments
·· The notes in the documentation were to be clear for anyone using the device, regardless of what microcontroller they're using of the potential output in volts.· One thing that needs to be factored in on a BASIC Stamp is that first there are clamping diodes on the I/O pins.· Second, in input mode the impedance of the I/O lines and the fact that this device is extremely low current mean there won't be enough current to make any difference.· Bottom line is you don't even need the Zener Diode.· As I said, I was being safe for all possible applications.
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Chris Savage
Parallax Tech Support
csavage@parallax.com
I begin to sound like a pompous idiot.
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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)
······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
·· Don't worry about it.· It's really not that big of a deal.· The main thing to know now, is that the BASIC Stamps and the SX Chip can handle the output directly, and there is no polarity, due to the nature of the device.· Remember ohms law factors in here as well.· It's not always just the voltage that can kill an input, it requires sufficient·current as well.· The clamping diodes can handle the little bit from the Vibra Tab.· Take care.
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Chris Savage
Parallax Tech Support
csavage@parallax.com