[Bridging_the_digital_divide] The piezo crystal question

[Richard Lisi]

>>> You probably got an answer by now, but....
>>>
>>> "Piezoelectric effect" is  used in piezo switches.  They are 
>>> designed with  semiconductor crystal materials that have been 
>>> "doped" with impurities(gasses etc.) to respond under an applied 
>>> physical pressure.  When not touched or unactivated they remain 
>>> neutral and may be nonconductive ( or... they could be "resistive" 
>>> as opposed to becoming superconductive depending on their "doping").
>>>
>>> As pressure is applied to the body of the switch crystal, such as 
>>> when pressed, stretched,twisted or squeezed, a voltage or charge is 
>>> produced during this changing pressure being negative on one side 
>>> and positive on the other side of surface of the crystal ( no charge 
>>> is produced at rest position).
>>>
>>> If the opposite action occurs, that is, not pressing , but 
>>> expanding, the opposite charge can and will result thus reversing 
>>> the polarity of voltage charge as the action occurs.
>>>
>>> This ability to give a positive or negative charge by physical 
>>> pressure is adapted to transistors. Unijunction, bipolar, or field 
>>> effect gated transistors can be biased(set up electrically) to 
>>> independently turn them on or off. This allows for a positive ("hole 
>>> flow") or negative (electrons) current to pass through them in one 
>>> direction or another or to be blocked completely.
>>>
>>> There are many manufacturers of piezoelectric products besides 
>>> switches such as microphones and speakers.  Microphones use the 
>>> changes in modulated voice or sound to produce voltages which may be 
>>> amplified.  Piezo speakers use the reverse action to produce actual 
>>> physical action of shrinking or expanding the crystal material as 
>>> voltages vary and are applied to the crystal. Remember if you can 
>>> produce one form of energy using some methodology in a certain way, 
>>> then there will always be a way to produce the original form of 
>>> energy through some reciprocal process all ready in production or to 
>>> be yet discovered (Lisi Theory). As an example, light emitting 
>>> diodes ( LEDs) produce light from charging particles and 
>>> photovoltaic cells produce electrical charges from lighting 
>>> particals.  Another example is the  piezo crystal microphone which 
>>> produces sound as charges are applied and modulated (adding 
>>> information through variation) compared with the piezo speaker in 
>>> your watch which makes voice or sound as it is modulated using 
>>> electrical charges to shrink or expand a crystal attached to some 
>>> sounding device or membrane which is vibrated.
>>>
>>> I hope this helps.
>>>
>>>
>>>
>>> Rick Lisi
>>>
>>> On Jul 6, 2004, at 11:19 AM, Jason Barkeloo wrote:
>>>
>>>> Jeff (or anybody),
>>>>
>>>> How does a piezoelectric switch work?
>>>>