[sdiy] Sequencer Interface connectors

[Tim Parkhurst]

So I'm thinking I wanted to throw together a cheap, simple little 8 step
analog sequencer. Then I'm thinking, what if I wanted to make another one at
a later date and hook the two together. I haven't really found anything that
would provide a means to easily daisy chain two (or more) sequencers. So
here's what I think you would need to do this:

*****************
A "Clock In" jack for a clock signal from upstream
A "Sequence End" jack for a end signal from upstream

A "Clock Out" jack for sending clock out to downstream
A "Sequence End" jack for sending end signal out to downstream

A mode switch that would allow selecting Serial, Parallel, or Independent
operation of each sequencer.
*******************

The Parallel and Independent modes would be easy. The serial mode is a
little trickier, but not impossible. Basically, at start up all sequencers
in the chain would be stopped and their outputs disabled (this is really
what makes the serial mode work). The CV outputs are summed together to
drive a single VCO, for example. Pressing START on Sequencer 1 enables its
output and starts it counting. Sequencer 1 would provide the clock signal
for the other sequencers when they are enabled. When Seq 1 reaches the end
of its sequence, it stops counting, disables its CV output (so that it
doesn't add to the CV and transpose the sequence), and sends a "Sequence
End" signal out to the downstream machine. When Sequencer 2 sees this
signal, it enables its output and starts stepping to the clock signal
applied at the "Clock In" jack. Sequencer 2 could use its own internal clock
if you wanted it to (just don't plug anything into the "Clock In" jack). The
same actions would repeat if you have three, four, or however many
sequencers daisy-chained together. At the last sequencer in the chain, you
run the "Sequence End" signal from the output jack back to the "Sequence
End" input on the first sequencer so that the whole thing will keep running.

If you did the logic right, you could just hook up three or four sequencers
and then quickly switch between parallel and serial combinations by just
using the mode switch.

I was also thinking of adding a "Transpose" mode. In this one, Sequencer 1
would run through its sequence, and Sequencer 2 would be advanced to the
next step by the "Sequence End" signal from upstream (Seq 2 would not use
the Clock signal). Both sequencers have their outputs enabled and are
basically running in parallel. If you summed the CV outputs together, then
Sequencer 2 would transpose the output of Sequencer 1. You could also use
the CV from Sequencer 1 to drive a VCO and the output of Sequencer 2 to
drive a VCF. Then the output of Sequencer 2 could be set to act like an LFO
synchronized to Sequence 1. 

Any thoughts? Has this already been done? It seems very handy, and I would
think it's been done before. I await your comments, criticism and collective
wisdom. 


Tim Servo
"Imagination is more important than knowledge." - Albert Einstein



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