[R-390] Wise's Barebones Ending the Moment of Silence

[Charles Steinmetz]

David wrote:

> My recipe here is functionally equivalent
> to Charles Steinmetz's.  His approach does away with the
> capacitance multiplier; instead, SLOW is a 22uF cap and MED
> is a 2uF cap, and each goes between the AGC line and ground.
> Nothing tries to establish the right charge on a cap before
> you switch it in.
>
> And that's that.  When you switch away from a cap, it retains
> for some time whatever charge it had.  If you switch back
> and the signal doesn't happen to be the same strength, the
> system will take a moment to adjust, exactly as if the
> station abruptly changed while you were listening.  This
> will give you a Moment of Less/More Loudness, and
> very short compared to the original Moment of Silence,
> because less charge needs to be added or removed.

I did, actually, address this issue in my comments.  From my 12/27/19 post:

> One further note:  While the "cure" prevents the massive DC transient on the AGC line and the associated "moment of silence," the "Medium AGC" and "Slow AGC" capacitors can still be left with residual charge (and, therefore, non-zero voltage) when switching to one of the other capacitors.  It is good engineering practice to include bleed resistors from each of these two capacitors to the AGC buss, so that the voltages on the capacitors are maintained near the current AGC voltage and even these much smaller voltage transients on the AGC line are minimized. The bleed resistors must be very large, with time constants of a minute or so.

This will work regardless of whether you switch the AGC Buss end of the 
capacitors or the ground end.  Just put the bleed resistors across the 
switch contacts, in either case.  The charge on each out-of-circuit AGC 
cap tracks the average AGC voltage over the last minute or so, so it 
will almost always be pretty close to the "right" value when it is 
switched in.  Transients are minimized.  Of course, the same trick 
should work with Dave's circuit.

Best regards,

Charles