Ugha, · Here is something that I experimented with awhile ago with mixed results.· I was hoping to be able to·transmit Audio (wireless bug), or something along those·lines, but I couldn't get the·resonant frequency high enough·to make that practical.· Instead, low frequency vibration worked ok.· Now, I didn't spend a great deal of time with it, so it could be refined and possibly made to work. · Another theoretical application for the Piezo Film Vibra Tab, that I would like to experiment with would be in the area of Surface Doppler Acoustics where you have two sensors equidistant from an acoustic source on the surface of an object , for example a table.· Based on where and how you touch the table you disrupt the signal being received by the Piezo Film Vibra Tab sensors.· A differential comparison would/could reveal the location of the acoustic disturbance. ·
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IC Layout Engineer
Parallax, Inc.
I'll bet you could do a very small earthquake(tremor) detector with that circuit and a Propeller
with an SD card/clock for logging. Shame I don't get that kind of activity here, or I might do it.
i use them to measure vibration of stuff, when my cousin used to live with me, we wouble tape a mass to the end of it, and then tape the sensor to his subwoofer in his car, we would then "know" what kind of vibration we were getting, we would then place them in various parts of his car and at certain distances away and measure the vibrations of the car, we actually would use them to find where high vibrations that would probably lead to a rattle. i am actually working with them this week to figure out the vibrations on a steam engine we are building for my small engines teacher. i am also working on getting a small display to act as a type of scope to graph the vibrations, once i get that working i am going to see where certain parts of the motor are and the likely problems of vibration come from
In the Parallax documentation, it gives a 'switch' application that I have a few questions on:
On the mounting, can I place it on a flat surface·and it still generates an 'on' (e.g. applying pressure), or does it need to be elevated for flexing?·
Will the response remain 'on' as long as I apply pressure to the sensor?· This is in particular to mounting on a flat surface
Will the voltage change if I apply harder pressure if applied to·a flat surface?
I would imagine there's a certain amount of force that has to be applied if·there's a 5.1 zener applied.· Can this force be generated on a flat surface (e.g. pressure)?
I have one on the front door of my shop, responds to people knocking (or trying to break in) with a light display in the window that varies with the time and intensity.
Yendor, be sure to download the Piezo_Technical_Manual.pdf from www.meas-spec.com, under the literature link. It has LOTs of applications in addition to good device info. You will see that one application is as an acoustic pickup, where the sensor is fastened to a surface like a drum or sounding board. The sensor has to stretch or flex, and static pressure will not work well unless it causes some stress and strain in the surface the sensor is attached to. Not constant, but changing. It gives an analog output, proportional, not on-off in the sense of a switch. It is more like a capacitor that accumulates charge as a result of flexing, and that charge will leak off into any resistance (MOhms) that is present across the sensor. In my opinion, the zener is not really necessary, because the sensor can't generate enough current to damage the Stamp anyway. The best thing to do is get one, and hook it up to an oscilloscope so that you can experiment for yourself.
Ugha
Posts: 543
Comments
·
Here is something that I experimented with awhile ago with mixed results.· I was hoping to be able to·transmit Audio (wireless bug), or something along those·lines, but I couldn't get the·resonant frequency high enough·to make that practical.· Instead, low frequency vibration worked ok.· Now, I didn't spend a great deal of time with it, so it could be refined and possibly made to work.
·
Another theoretical application for the Piezo Film Vibra Tab, that I would like to experiment with would be in the area of Surface Doppler Acoustics where you have two sensors equidistant from an acoustic source on the surface of an object , for example a table.· Based on where and how you touch the table you disrupt the signal being received by the Piezo Film Vibra Tab sensors.· A differential comparison would/could reveal the location of the acoustic disturbance.
·
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Beau Schwabe
IC Layout Engineer
Parallax, Inc.
I'll bet you could do a very small earthquake(tremor) detector with that circuit and a Propeller
with an SD card/clock for logging. Shame I don't get that kind of activity here, or I might do it.
OBC
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humanoido
- On the mounting, can I place it on a flat surface·and it still generates an 'on' (e.g. applying pressure), or does it need to be elevated for flexing?·
- Will the response remain 'on' as long as I apply pressure to the sensor?· This is in particular to mounting on a flat surface
- Will the voltage change if I apply harder pressure if applied to·a flat surface?
- I would imagine there's a certain amount of force that has to be applied if·there's a 5.1 zener applied.· Can this force be generated on a flat surface (e.g. pressure)?
Also the web site in the documentation www.msiusa.com·is not correct.· It should be www.meas-spec.comMany thanks!
Rodney
·
Yendor, be sure to download the Piezo_Technical_Manual.pdf from www.meas-spec.com, under the literature link. It has LOTs of applications in addition to good device info. You will see that one application is as an acoustic pickup, where the sensor is fastened to a surface like a drum or sounding board. The sensor has to stretch or flex, and static pressure will not work well unless it causes some stress and strain in the surface the sensor is attached to. Not constant, but changing. It gives an analog output, proportional, not on-off in the sense of a switch. It is more like a capacitor that accumulates charge as a result of flexing, and that charge will leak off into any resistance (MOhms) that is present across the sensor. In my opinion, the zener is not really necessary, because the sensor can't generate enough current to damage the Stamp anyway. The best thing to do is get one, and hook it up to an oscilloscope so that you can experiment for yourself.
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Tracy Allen
www.emesystems.com
I'm seeing the light - thanks! I agree some experimentation is necessary, just wanted to make sure I'm going down the right path.
Rodney