[sdiy] digital delay, was ...

[jhaible at debitel.net]

> The "Wilson Analog Delay" as provided in Serge set-ups apparently has 
> some capability to process CV's. I have not used one personally, but was 
> told that the process used is something like the FM method Harry 
> suggested, normally used to delay envelopes. Feed audio-freq sine wave 
> into VCA, contour it with env gen, feed into WAD and use envelope 
> follower to extract delayed envelope signal. Anyone who has used one of 
> these care to comment?
> Regards, Mike

I've never seen one, and I have no idea if the Serge WAD works like this,
but it's agreat idea for sure!

You would use a sine carrier that is tracking the clock frequency
(fixed divider ratio). Maybe 1/2 fclock will work, if your 
modulator ("DC") is slow enough not to create notable sidebands.
Maybe even a square wave at 1/2 fclock will work (not sure!), because
the harmonics will be "aliased" to frequencies that don't matter?
So you'd have real chopper operation. This will give you low
offset voltage. But the _scaling_ of your delayed CV might still
be dependent of the delay time, so delaying precise V/Oct CVs
still seems to be difficult.

JH.

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