[sdiy] Gate outputs.. 0v or ground?

[Paul Perry]

The problem isn't at the 0.0 V / ground side, because the
circuit you are connecting to, can't tell whether it is a
short to ground, or whether it is a low impedance
output at zero volts.

At the OTHER end......
say you take the gate input to a MS20.
When there is NO input to it from the external world, then
it is holding itself up to a certain voltage by a pullup resistor.

And it is easy to turn it on, by either shorting (hence the name S-trig)
or by applying zero volts (same effect).

But how to apply "no connection" to it from logic?
Forunately, sending say 10V + to it, doesn't appear to hurt it.

paul perry Melbourne Australia

----- Original Message ----- 
From: "Mike Beauchamp" <mikebeauchamp at gmail.com>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Thursday, February 22, 2007 2:00 PM
Subject: [sdiy] Gate outputs.. 0v or ground?


> I have a simple question about gate inputs, but no hardware to quickly
check...
>
> When a gate output (or v-trigger) is LOW, it's at 0 V right? Does that
> mean it is "open circuit", or grounded, or somewhere inbetween? If
> it's inbetween, what is the resistance to gnd?
>
> I'm building a super-simple VCO and I want it to be able to respond to
> a gate signal to tell it when to actually output audio. I'm also
> working on a really simple switch that can output the gate signal, and
> I don't know if I should be grounding the output when the signal is
> LOW, or just leaving it open circuit, or having some resistance to
> ground. I'm also wondering if maybe I should be buffering my gate
> output?
>
> The way my VCO works right now, it responds to a gate signal that is
> >2V for HIGH and GND or around 100K resistance to gnd for LOW. If I
> leave the gate input open circuted, the VCO assumes gate is also HIGH.
> So you can see how if standard gate signals go from example 5V HIGH
> and open-circuit LOW, my VCO won't make a distinction.
>
>  Thanks in advance..
> Mike
>
>
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