Yamaha DTXpress/DTXplorer/DTXtreme

--- In DTXpress@yahoogroups.com, "Chris Todesco" <desco911@y...> wrote:
> Keith, PFozz, plhalli, et al:
> 
> Anyway, I tried out your circuit last night (with a Roland TD-7t box 
> and pads), but I had bigger problems...  The main pad (J3 in the pdf) 
> was severely cut down on the sensitivity, and same as plhalli, the rim 
> pad (J1) was sensitive enough, but wouldn't trigger the switch for 
> lighter hits.

I have managed to get my hands on a Roland tom pad for a quick test. 
While the polarity is negative, there is plenty of positive going
signal as well.  However, if the Roland module only takes notice of
the negative going signal, a diode as I have drawn it would be a bad idea.

Could you try something?  Fit both D1 and D2, but the opposite way
round to my diagram!  This should give the isolation between the two
piezos, still drive the transistor for the rim switch and allow the
negative pulses through for the Roland module.

Keith.