[sdiy] touchplate keyboard - works!

[Scott Gravenhorst]

"Roy J. Tellason" <rtellason at blazenet.net> wrote:
>On Saturday 05 February 2005 02:05 pm, Ian Fritz wrote:
>
>> I'm missing something. Could you clarify how you get a pressure output? It
>> seems to me the piezos just put out a pulse. In fact, it's impossible to
>> get a dc voltage from a piezoelectric transducer, since they are
>> capacitive.
>
>Eh?  A piezoelectric material is defined as one where,  when you apply a 
>mechanical force you get a voltage,  and vice versa.  Same principle that's 
>used in crystal-controlled oscillators,  too.
>
>They may be "capacitive" in the electronic sense,  but that doesn't change the 
>principle of operation...

As far as I understand it, the electrical discharge occurs only while the force
applied is actively changing.  Once it stops changing, so does the current.  Is
that correct?


---------------------------------------------------------
- Where merit is not rewarded, excellence fades.
- Hydrogen is pointless without solar.
- What good are laws that only lawyers understand?
- The media's credibility should always be questioned.
- The only good terrorist is a dead terrorist.
- Governments do nothing well, save collect taxes.

-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
-- Linux Rex         | RedWebMail by RedStarWare
-- FatMan: home1.gte.net/res0658s/fatman/
-- NonFatMan: home1.gte.net/res0658s/electronics/
-- Autodidactic Master of Arcane and Hidden Knowledge.