Re: ANL circuit

On Fri, 21 Apr 2006 17:46:51 -0400, T. Atkin wrote:

Hi all,

I'm looking for a _simple_ automatic noise limiter (or noise gate) for
non-hifi use like AM radio. I remember ANL in old CB transceivers using very
few components but can't find any schematics. Googling just returns
equipment stuff, no schematic :(


Find a point in the audio path where you expect the signal to be about
1 - 1.2 Vpp, and put antiparallel signal diodes to ground there, like
1N914s or 1N4148s. You shouldn't have to add any resistors, because
existing impedances should take care of that. That just simply limits
the P-P voltage excursion; it doesn't make the noise go away (it's not
a noise _blanker_), but it does _limit_ it to at least a reasonable
signal level. You could even put it in a gain-controlled circuit and
play with limiting of ordinary audio - voice, anyway, can take a
surprising amount of limiting and still be intelligible. Some people
call this "clipping", but I think clipping has much sharper "corners",
where limiting softens them a little. :-) (that's the corners on a
'scope display, has nothing to do with bandpass. :-) )

Hope This Helps!
Rich


.

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