Piezoelectric Speaker Substitution in BASIC Stamp Lessons
Ol' Geo
Posts: 30
Hi, folks...
As I am studying Stamps in Class course, I notice some upcoming lessons would require piezoelectric speaker for experiments. Because of my deafness since infancy, I would not be able to follow the leassons without outside hearing help. I wonder if there is such a substitution for the speaker such as vibrating apparatus, perhaps a piezoelectric vibrator (not sexy one, mind you.) Deaf students would be able to feel vibration instead of listening during the study.
I understand Parralax does not sell such an apparatus. Anyone has a suggestion? Would very much appreciate it.
Thanks.
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Ol' Geo
Retired Software Engineer
An oscilloscope is a window of unseen electronic world. - GM
Post Edited (Ol' Geo) : 9/17/2007 4:37:44 AM GMT
As I am studying Stamps in Class course, I notice some upcoming lessons would require piezoelectric speaker for experiments. Because of my deafness since infancy, I would not be able to follow the leassons without outside hearing help. I wonder if there is such a substitution for the speaker such as vibrating apparatus, perhaps a piezoelectric vibrator (not sexy one, mind you.) Deaf students would be able to feel vibration instead of listening during the study.
I understand Parralax does not sell such an apparatus. Anyone has a suggestion? Would very much appreciate it.
Thanks.
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Ol' Geo
Retired Software Engineer
An oscilloscope is a window of unseen electronic world. - GM
Post Edited (Ol' Geo) : 9/17/2007 4:37:44 AM GMT
Comments
The key is discarding the peizo element and working with the port.
Code can toggle the port high and low, so why not use a blinking
LED? It may be more easy to see a light than constantly keep
a finger on a sensor.
humanoido
Geo
Having a little background in bio-feedback sensory mechanisms, for most if not all of the lessons, you could use a standard 8 Ohm speaker (size of your choice)...
To "feel" the frequency you could place your fingers (lightly) on the speaker cone. For higher pitched sounds where the vibration might be too small to distinguish,
you could feed the speaker a second frequency in a bridge amplifier configuration so that it creates a beat frequency that can be felt.
i.e. If you are trying to "feel" 2000Hz, combining it with a second frequency of 1900Hz would create a Beat frequency of 100Hz AND 3900Hz... you will be able to
"feel" the 100Hz much easier than 1900Hz, 2000Hz , or 3900Hz.
Let me know if this sounds (no pun) applicable, and I will try to put a schematic together for you and others that may benefit.
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Beau Schwabe
IC Layout Engineer
Parallax, Inc.
Beau, yours might be more applicable. Yes, I understand what you meant about beats in music. I already studied "What's a Microcontroller" lessons. Big help, indeed. I had an experience with speaker's cone vibrating in the past. The problem is that I ain't no hardware guy but can read schematic. Would very much appreciate if you supply a schematic showing how to "hook up" the magnetic speaker with BASIC Stamp board. I understand the speaker needs more power than the board, correct? If you are interested in knowing about the vibrating mouse that is soon to market, I'll supply the info.
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Ol' Geo
Retired Software Engineer
An oscilloscope is a window of unseen electronic world. - GM
Thanks.
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Ol' Geo
Retired Software Engineer
An oscilloscope is a window of unseen electronic world. - GM
http://www.collegeofsoundhealing.co.uk/pages/cymatics.html
Geo
PS I could be wrong that Parallax does not sell small mikes for BS boards. Couldn't find them at their website.
PSS I don't like salt spilling over me. [noparse]:)[/noparse]
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Ol' Geo
Retired Software Engineer
An oscilloscope is a window of unseen electronic world. - GM
Yikes!
You apparently negected to mention that the 8ohm speaker CANNOT directly connect to the BasicStamp as it would pull too much current.
I am setting up a 'one transistor/ one resistor' amplifier to drive a speaker. While it isn't pure audio in the sense that the square waves are not smoothed to sine waves that swing from plus to minus, it is a minimal approach that can be fit onto a breadboard and existing power. {True sine waves require a dual power supply, like +5 and -5 volts}
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"Everything in the world is purchased by labour; and our passions are the only causes of labor." -- David·Hume (1711-76)········
If you require the visual representation of the sound use this software
http://www.zeitnitz.de/Christian/Scope/Scope_en.html
It's a PC sound card oscilloscope - it will let you see the waves coming from the piezo,it's free and will us the same microphone.
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Have Fun
TR
Post Edited (TechnoRobbo) : 9/18/2007 10:28:56 AM GMT
I was thinking of the method similar to what is described·in the Stamp manual (see attached) for driving a speaker, but I have not had time to do any testing.
15Ohm + + + 15Ohm I/O #1 >--/\/\--||---o---||----o---||--/\/\--< I/O #2 10uF | 10uF | 10uF | | | | o SPEAKER o + - I/O #1 - Frequency from Stamp you want to hear I/O #2 - Fixed Frequency from 'another' Stamp, 555, etc. Note: The Speaker should be approximately 8 Ohms.·There is nothing wrong with using a 1-Transistor amplifier, you might even totem-pole two transistors so that you have two separate inputs.
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Beau Schwabe
IC Layout Engineer
Parallax, Inc.
Post Edited (Beau Schwabe (Parallax)) : 9/19/2007 6:59:56 PM GMT
Substitue the Pizo Speaker with a small pager vibrator, resistor and a small signal NPN transistor. Use a long 3 conductor servo extention wire to connect the circuit to the stamp. The vibrators are cheep and available from Mouser and or Digikey and or Jameco. Choose a 3VDC 80mAmp model. The NPN transistor can be any transistor with a greater then 200mAmp collector current (2 times the motor current to be safe) and a Bata of greater then 25. (80 mAmp / 25 = 3.2 mAmp) The Stamp can supply up to 25 mAmp. Use a base drive resistor between 200 ohm and 1.3K ohm (1300). Closer to 1.3K ohm would be better.
Stephen Wagner
Geo
Glue the pizo to the bottom of a bowl of water. It should produce acoustic waves in the water. Or, current amplify the stamp signal and drive one of the cheap surplus solenoids glued to one solid piece of wood and the armature glued to a second piece of wood that could be felt by the students fingers.
Good luck
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D. A. Wreski
A deaf person could live a better life in the name of Electronics!
Geo
Post Edited (Ol' Geo) : 10/16/2007 7:48:28 PM GMT
1. Frame
2. Circular bowl (square would cause wave-bounces and interference patterns from the corners)
3. 4 Springs (stiff)
4. Time and effort
Build a simple, heavy frame with four uprights, one at each corner. Mount the bowl to these uprights using stiff springs to all for some movement. Attached amplified piezo or vibrator to the bottom of the bowl. Fill the bowl with coloured water, and watch those waves dance!
The springs have to be stiff enough not to woble easily, but stiff enough that the bowl will move slightly when triggered.
I saw this on TV once, can't remember what it was but they were just touching vibrating objects to the bowl, rather than permanently fixing them together.
Different coloured food dye works wonders - experiment as different lighting in the room can make different coloured water easier to work with.
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Flying is simple. You just throw yourself at the ground and miss.
"I think computer viruses should count as life. I think it says something about human nature that the only form of life we have created so far is purely destructive. We've created life in our own image."
Stephen Hawking
Post Edited (Morrolan) : 10/17/2007 5:11:31 PM GMT