[sdiy] what is trigger signal?

[Grant Richter]

Hi Alex,

These apply mostly to monophonic keyboards.

In the ARP standard, a Gate signal is a signal from the keyboard (or other
controller) the indicates a key is pressed. It goes active and stays active
as long as at least one key is depressed.

But what if a new key is depressed before the old one is let go? There needs
to be a "new key" signal that will "trigger" a new attack for that note from
the envelope generator. That is the Trigger signal, for the most part it
indicates a new key has been pressed, even if the old one is not released
yet.

It is a short electrical pulse, hopefully, not shorter than 1 millisecond.
It is usually positive going. Very short trigger pulses can cause problems
when interfacing between equipment from different manufacturers.

Interesting control waveforms can be obtained by routing two different
square wave LFOs to the Gate and Trigger inputs of an ADSR envelope
generator.

> From: Alex Dickey <Alex at centricitysoftware.com>
> Reply-To: owner-synth-diy at node12b53.a2000.nl
> Date: Wed, 21 Feb 2001 10:17:50 -0800
> To: "synth DIY (E-mail)" <synth-diy at node12b53.a2000.nl>
> Subject: [sdiy] what is trigger signal?
> 
> i *excel* at these newbie questions...
> 
> what is trigger signal?  just a surge of voltage?  how is it different from
> a gate signal?
> 
> thanks,
> alex
>