[sdiy] Sequencer thoughts

[Peter Grenader]

All,

I am in the midst of my annual 'think about making a counter-based
sequencer' pilgrimage.  It came about this time because I got two Blacet EGs
recently (highly recommended to anyone who takes synthesis seriously) and i
need a means to control all phases of the ADSR or AD with fixed voltage,
but having a separate, tunable voltage source for each phase (four banks).

High on my list of needs for any sequencer is control of direction, random
most important among that and I hoping for some input from the group on the
best (read: easiest) way of accomplishing this.

For clarification, I am mapping out a 4 bank, eight step sequencer.

I was thinking of an engine which consists of 4051 demux which is being
driven by a 4516.  Easy enough.  For the random, I was going to utilize the
present inputs of the 4516, which would receive binary data which is latched
by a 4042 by the same clock which was advancing the 4516.

It's where the 4042 is getting its four bit data that I am scratching my
head about.

Options I've come up with are:

1)  A single four bit data stream (another 4516) run at a super-high
frequency which, when gated by the 4042 at a considerably lower freq, should
give me quasi-random four bit number streams. A four bit sample and hold of
sorts. I believe this is how Serge did it, although I have not seen one of
those schemo's in a few years.

2) Four independant white noise signals into four different comparitors, the
output of each  routed into 4042 latch inputs.  Not sure what in the hell
would happen there, but it seems less random than option 1

3)  Make four different clock circuits running at four different frequencies
and route those into the 4042 latch inputs.  This seems like it would give
better results than option 2, and would require less circuitry (for me, a
big thing).

4)  The old LM3914 trick - using one of these bad boys with a single signal
input which would be attenuated so that only the first four comparators
would be active.  At this point, it would allow all sorts of direction
control, not just random.

I am going in the direction of 1 or 4.  Any input, along with any other
methods you might recommend, would be GREATLY appreciated.

thanks for your time,

PG