switching at zero cross/noiseless switching

Don Tillman don at till.com
Thu Nov 11 16:21:06 CET 1999


   Date: Wed, 10 Nov 1999 22:39:46 -0800
   From: Buck Buchanan <voltagecontrolled at home.com>

   > You're thinking of delaying the switching until input A crosses
   > zero, right?  But then it's unlikely that input B is crossing
   > zero at that very moment and so switching to input B will 
   > cause a click.  It would be no less noisey.

   I think I should have explained the module better.  It takes one input
   and fans it out to one of 4 outputs.  So there's only signal A - there's
   nothing at B (C or D) until A is switched there.

Oh, well, that's very different from what I was picturing.  I'm off in
a parallel universe then.  

   From: Martin Czech <martin.czech at intermetall.de>
   Date: Thu, 11 Nov 1999 08:55:31 +0100 (MET)

   I have experienced that a continuous signal like this gives no pop, but
   a click.  The first derivative or higher order derivatives are likely
   to be not continuous, ie. the signal is not "smooth".

Okay, just for grins, here's another one...

>> Proposal 5

Delay switching until the *derrivative* of the input signal is zero, 
Then use a capacitor slowly discharging from there to bring down the
dc level.

  -- Don






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