Yamaha DTXpress/DTXplorer/DTXtreme

--- In DTXpress@yahoogroups.com, "bznx9c" <bznx9c@...> wrote:
>
> Here it is, please find the PiezoSwitch.jpg in the Files section. 

You might want to make the threshold adjustable with a potentiometer
instead of fixed resistors.  Also, you might want to put a resistor in
series with the inverting input (maybe 100k) to protect the comparator
input.  You can easily get 15V out of the piezos which could blow up
the comparator if you are running it on less than that.

Your circuit will work fine, and be more sensitive than the one I have
been proposing.  However, I tried to get away from power supplies for
a few reasons - risks of liabilities blowing up other people's
modules, cost, regulatory issues, and supplying it to different
countries.  I did build a complex system with gain in the rim switch
side as well to overcome the DTXpress module's lack of rim sensitivity
- see "DTXpander E.pdf" in the files section.

As it is, I will probably have to stop selling ready built modules to
people due to WEEE regulations.  

Keith.