[sdiy] Re: [AH] AD converter was.. Re: MILTON [AH] News affecting...

[Peter Grenader]

To anwser J's question below in regard to the operation of the Milton CV
input:

<<Hello,
> 
> The CV input signal looks very interessing, but I've got a question. The
> state is calculated by using a AD converter. What is the sample rate of the
> converter? Will noise as cv input result in random steps at random time or
> is it possible to use the clock input as S&H control signal for the cv
> input? 
> That would be nice, because then you can get random synced sequences,
> without spilling a S&H module in your modular.
> 
> A nice-to-have, not a must-have.
> 
> Kind regards,
> JohnnyBusca
> http://www.tonyblack.org>>

John,

The short-form answer to your question is 'All of the Above'.  Allow me to
explain.

The control voltage input to the Cynthia Milton has three modes of operation
(one async, two synchronous). You will notice a toggle switch labeled
'SENSE' next to the CV input.  It is a three position toggle, to wit:

A)  Mode A (Std)

In this SYNCHRONOUS mode, the voltage present at the CV input will not
effect the sequencer count unless it rises above .18 volts. Being
synchronous, the changes from that CV ARE PACED TO THE MAIN CLOCK.

This inhibiting comparator was included so that an operator could
effect/interrupt an otherwise 'normal' (left to right) sequence periodically
while it was running.

As an example, if an envelope generator was connected to the CV input, it
would have no effect on the counting sequence until it was fired.  At that
point, the curve of the envelope would dictate the direction and selection
of stage assignment.

This mode reflects a power of 1 cv response (more on that in a second).

B) Mode (Power of 2, non gated)

In this SYNCHRONOUS mode, the voltage present at the CV input will override
the counting sequence regardless of the voltage level present.  What this
means is when the voltage is sitting idle (ground), the sequencer wll sit at
stage 1 waiting for a change to the CV input in which to determine it's next
location, regardless of the fact that there is an incoming clock going to
the sequencer.  At that point, it doesn't care.

Like mode A, mode B is also synchronous. The changes from that CV ARE ALSO
PACED TO THE MAIN CLOCK.  So, inserting noise into that input will give you
random stage assignment of your presets, paced to the speed of the incoming
clock of the sequencer.

This mode reflects a power of 2 CV response - twice that of Mode A.  In mode
B the incoming voltage is passed through a voltage doubler which features an
internal trimpot that allows the user to set or change the sensitivity of
the cv to +/- 10% of times 2 response.  The X2 sensitivity was added so that
a 1V/oct keyboard could be used like a programmer - which each adjecent key
incrementing or decrementing the current stage by 1.  In short - 16 adjecent
keys on a keyboard will act control Milton like the 16 touchpads of a TBK.

And it is exactly X2: If you insert a static voltage into the input while in
Mode A which holds the sequencer to step 5, flipping the SENSE switch to
Mode B will force the sequencer to stage 10 immediately.  If on stage 4, it
will jump to stage 8, 2 to 4, 8 to 16, etc.

C) Mode C (ASYNCHRONOUS)

This mode is identical to Mode B, but is asynchronous - it is NOT paced to
the incoming clock.  Stage assignment is determined purely by the voltage
level of the CV input and occurs in real time when the increment is
sufficient to effect a change.

Connecting noise into this input will give you very quickly paced random
step assignment.

The refresh rate of the A to D is approximately 22 Khz.

I hope this addresses your questions  - please feel free to fire off more at
any time. 

best,

Peter Grenader