[sdiy] what is trigger signal?

[Terry Michaels]

Message text written by INTERNET:grichter at asapnet.net
>Just as an additional aside...

Buchla systems carry the Gate and Trigger signals on the same wire. This
means you do not have to patch two wires for Gate and Trigger.

The Gate is a sustained +10 volt signal and Triggers are short pulses that
go above it to +15 volts. The output has a passive resistive mixer that
combines the Gate and Trigger signals. There is a small PNP transistor that
pulls the gate line to the +15 volt supply, past the Gate circuit current
limiting resistor. The Trigger transistor has it's own current limiting
resistor in series. The Gate/Trigger signal is then diode isolated, so all
the G/T lines can be wire-ORed.

The two signals are separated at the receiving modules with simple voltage
comparators. <

Hi Grant:

I really like this approach.  In fact, I am using this method in the new
modular system I am currently building.  As you said, it gives you both
gate and trigger in one wire, patchable with one cable.

The only disadvantage I can see is, there are some cases when you don't
want envelope generator re-triggering when playing legato.  In that
situation, you can't defeat the "new key trigger" by simply pulling out the
corresponding trigger patchcord.  It will require throwing a front panel
switch to turn it off.

Terry Michaels