Archive of the former Yahoo!Groups mailing list: MOTM

This post is mostly cut and paste from emails I have sent privately, so
you'll have to forgive me if it seems a bit choppy.

Back in December, I sent Paul S. my idea for a "mini-sequencer". Later, I
sent the idea to Larry, and he came up with a brilliant idea for an
expander module.

The CV thru function is what makes this "mini-sequencer" work, and afaik,
it's an original idea. I haven't posted it anywhere up until now because
of the risk of manufacturers stealing ideas. However, since it might be a
while before I can invest in PCB software, and Moe seems ready to go, I
thought it would be best to post this now.

Moe came up with the idea of a modular sequencer with a "division of labor"
spread over many modules. I like that idea. The problem is that it
requires a large investment from both the manufacturer and the consumer
before a complete system is realized.

Like the "mini-moe", my idea was a stand-alone 2U mini-sequencer that can
be used by itself, or linked together in various multiples. This would
require much less of an outlay in parts to produce an initial run than a
"mother of all sequencers", and it would use PCB's and panels of a size
already used by the majority of the modules already being made. It would
also be much more affordable and an easier kit to build.

Overall, I agree with what Moe has said so far. I agree that in order to
avoid redundancy and minimize cost, this module should not contain an
internal clock or a quantizer. Any module from the 300 series could be
used as a clock, and the mini-wave does quantizing functions.

I also like the idea of being able to use different clocks for this
"mini-sequencer", especially considering it is both a gate sequencer and a
step sequencer in one module. I was thinking of using the clock to
directly generate the gates (by using the clock with AND gates). This
keeps the timing tight, and the pulse width of the gates is approximately
the same as the clock.

However, I do not know whether a PIC is the way to go. I don't know
anything about PIC's, but I think discrete CMOS might be easier and less
expensive (how is that for a qualified statement?? :) If it uses a PIC,
Moe will have to produce both a PIC and a PCB. Also, the CD4000 series can
run directly off +15V. The whole thing could probably be built with less
than $10 worth of board parts.

The module is a 2U combination 1-channel four-stage voltage sequencer and
four-stage gate sequencer. By itself, that's enough to sequence a bassline
and a couple of drums. Two units can be added together to make a 8∗1 step
sequencer or a 4∗2 step sequencer, three units can be added together to
make 12∗1 or 4∗3, four units can make a 16∗1, 8∗2, or 4∗4, etc. As you
will soon see, multiple units can be patched together in even more
interesting ways.

It has four knobs, and 9 jacks, and a toggle switch with two "regular"
positions and a momentary position (NKK M2029ES1W014 ??), such that:

KNOBS:

CV STEP 1
CV STEP 2
CV STEP 3
CV STEP 4


JACKS:

CLOCK
RUN RESET CVIN CVOUT
GATE 1 GATE 2 GATE 3 GATE 4


SWITCHES:

MODE: ONE-SHOT/STEP/SET


A switched jack for RUN is normalled to a sufficient voltage, so without a
jack, RUN is high.

In STEP mode, if RUN is high the sequencer advances forward with the clock,
the sequencer will continue to advance on each clock pulse as long a RUN is
high, but it will pause if RUN goes low.

In ONE SHOT mode, it will start when RUN goes high, but continue to advance
forward with the clock until it reaches the fourth stage or until reset
goes high, even if RUN goes low.

When RESET goes high, the sequencer skips to the first stage.

When the MODE switch is momentarily contacts SET (debounced!!) the
sequencer advances one stage -- this is quite useful in adjusting the
voltage output for each stage.

The sequencer has an internal bit for "running status" (please note that it
is not the same as RUN). If running status is high, then CV OUT is the
knob value for that stage. If running status is low, then CV OUT is CV IN.
While this might sound horribly confusing at first, but it should actually
be quite simple in practice.

By setting several modules to ONE SHOT mode, chaining the output of GATE 4
from each module into the RUN input of the following module, then finally
taking the last gate output of the last module to the RUN of the first
module, the modules will run in series and continue to loop as one big
sequencer. The sequence can be initiated by using sending the first RUN
jack a 5V trigger with a mult.

By chaining the CV connections together, CV IN is routed to CV OUT when the
sequence in one module ends and continues on in the next module. This way
several sequencer modules can be chained together with the last CV OUT
going to the VCO or whatever is being sequenced.

The MOTM system is very exacting about voltages, and the VCO's are very
precise. The input impedances are high, and an output impedance of less
than 100 ohms is required for the 820 bypass to work. So we need output
amps with less than 100 ohms that can drive shielded cable, and the lowest
possible offset for non-knob voltages.

Besides triggering envelopes and other modules, the GATE outputs can be
used as inputs to RESET, RUN or CLOCK on any of the sequencers. The system
is extremely flexible. Several units could be configured not only as a
large step sequencer, but also as pattern sequencers. Individual modules
could run off of different clocks in any combination. By multing the gate
output of the last stage used to both the RESET and RUN of the first
module, a sequence of any number of stages can be created. If you want a
bigger sequencer, the system can be expanded vertically or horizontally in
any direction simply by adding more modules!!

Additional modes of operation could also be added by adding more switches.


So the "mini-sequencer" would look like this:

l O
O
s O
x O
xxxx
xxxx

O - knob s - switch l - leds x - jack


The core can be built from two flip-flops and a 4052 mux. This also
provides a two-digit binary number for each stage.

Larry had the idea for an expander that uses a connection behind the panel.
One MTA100-4 could carry clock, stage number, and running status.

A two-channel expander would require 2 CV ins and 2 CV outs. With four
more gate outputs, that's eight knobs and eight jacks. So it would be
4-stage, 2-channel, and 2U, which would match up horizontally. The
expander module could carry that same header to the bottom of its PCB in
case you wanted to add two more channels or some other sort of expander.