How to use Basic Stamp to actuate the piezoelectric film to excit the structure

cornetlin

Hi
My idea is use Basic Stamp to actuate the piezoelectric film to excite the structure.
Then use other piezo film to detect the signal.
My question is, I don't know if base on the purpose, What components that i should buy to implement this device.
I have Board of Education Full Kit Serial and USB compatible now, but i don't know what else i could buy for this project.
By the way, i am not a EE background,so anybody can help me please ?

Thank you very much.

wintonlin

cornetlin

Could anybody can help me?

Or i should post in other forums
Thank you very much.

wintonlin

D Faust

If you get a piezo electric buzzer (not the kind with the boe-bot, one that makes noise when just connected to ground and Vdd.) you can turn it on and have a recieving buzzer that will generate a small voltage whren it gets the signal.

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--DFaust

metron9

If you use a comparator with the receiver (piezo buzzer) you can snap your fingers across the room and it picks up the sound wave.
I use LM393's for my acoustic lights and a small piezo buzzer (CEP-1110) for the pickup. I use a 10K pot to ground to adjust the sensitivity.

You can not use a piezo that has electronics on it like a radio shack piezo buzzer that runs on 12V, there is a tiny circuit on those. Also the magnetic buzzers dont work very well either.

Check out www.MSIUSA.com they have lots of information on piezo sensors.

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Think Inside the box first and if that doesn't work..
Re-arrange what's inside the box then...
Think outside the BOX!

Phil Pilgrim (PhiPi)

Parallax sells a piezo film sensor, and the product page includes documentation and sample code for its use with a BASIC Stamp. While most piezo-electric materials can be used "in reverse" to generate vibration from an AC voltage, nothing about such an app is mentioned in the docs for this product. Moreover, whether a piezo actuator would be adequate to "excite" your "structure" depends on the structure's size and stiffness, among other characteristics.

A little more information from you about your exact application will enable people to help you better.

-Phil

cornetlin

Hi guys,
Thanks for all your reply.
I have the Piezo Film Vibra Tab Mass now.
Yes, My application is like used the Piezo Film "in reverse" to generate vibration.
I know whether a piezo actuator would be adequate to "excite the structure depends on the structure's size and stiffness, among other characteristics. It is very important.
But now, i just can do the simple things that to generate vibration via in reverse the piezo.Then i can test the adequate of piezo actuator in next step.

So, If i want to used the Piezo Film "in reverse" to generate vibration.
Whats any other components should i buy for my purpose.

Thank you very much.

Mike Green

Most piezo films require a high voltage to get much movement out of them. You might use a transformer to get a voltage more like 50V from the 5V available from a Stamp. You'll need a diode (like a 1N4001) connected in reverse across the primary of the transformer to prevent the back EMF from destroying the Stamp's I/O pin. The secondary of the transformer you'd connect across the piezo sensor. A cheap audio transformer would do, maybe with a 1:5 or 1:10 turns ratio.

Others may have more suggestions. I haven't actually tried what I suggested, but it sounds reasonable.

Phil Pilgrim (PhiPi)

Mike is right: you will need a higher voltage than the Stamp can provide. An alternative to a transformer for this purpose is a so-called "peaking coil". The attached circuit shows an example. When the MOSFET gate is pulsed high, the drain is pulled to ground, forcing the inductor to conduct current. When the gate returns low, the drain is released, but the current in the inductor continues to flow, raising the voltage at the cap to a level higher than 5V. By rapidly pulsing the gate, you will end up with an AC waveform on the piezo film whose peak-to-peak voltage is much higher than 5V. The purpose of the drain resistor is to limit current through the inductor and MOSFET in case the gate gets stuck high. The gate resistor is there to keep the gate low if the Stamp pin floats (e.g. during reset and program uploading).

As to actual values for the illustrated components, you'll just have to experiment. I haven't built the circuit, so I can't make any recommendations.

-Phil

cornetlin

Thank you very much,
I Will try that all you mentioned.
If i success, i will post here.

Thank you very much.


wintonlin

Tracy Allen

I'd suggest you read the piezo film sensors technical manual from Measurement Specialties Inc. I'm guessing that is the kind of film you have. Great stuff. The technical manual shows how to both sense and excite the film, including examples of liquid measurement, hydrophones and speakers. It actually does not take much voltage to excite that PDVF film. You can roll a thin sheet into the form of a cylinder and apply freqout from the BASIC Stamp, and you can hear the tones.

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Tracy Allen
www.emesystems.com