[sdiy] simple noise gate circuit?

[Tim Parkhurst]

On 2/14/06, gregory zifcak <zifcak at hotmail.com> wrote:
> hi,
> i'm trying to get rid of bleedthrough on a few devices (realistic reverb,
> ring mod, nintendo). any ideas for a simple noise gate circuit? i don't mind
> if it's a somewhat harsh clamping down on the signal below the threshold. it
> would be fun to have a variable threshold, but if this complicates the
> circuit i can forget about it. i'm guessing a noise gate is basically an
> envelope follower controlling a vca; how can i do this with the least amount
> of parts?
> thanks for any suggestions,
> greg
>
>
>

A comparator (with hysterisis), controlling an analog switch? This
would be really simple, but the action would be ON or OFF with no fade
or transition between. Even better, how about a comparator controlling
an optoisolator? Pick a reasonably fast optoisolator (or even build
your own from an LED and a photocell), and use an A/R type circuit to
control the on and off times (within the limits of the phtotocell
response time, of course) with the signal from the comparator acting
as the "gate."


Tim (my action is either ON of OFF too, come to think of it) Servo
--
"Imagination is more important than knowledge." - Albert Einstein