[sdiy] Percussion sequencer idea

[Dave Magnuson]

Hi List,

I'm working on an idea for a percussion sequencer, and I'd like to hear
peoples' opinions on my concept before I go through and design/breadboard
it.  Here's my plan:

I want to use a Blacet MIDI to DIN-Sync IC to provide clock pulses @
24ppqn.   I'll run that through a divide by 3 circuit to get 8ppqn or 32nd
notes.  I was planning to use (3) J/K flip-flops for divide by 3, or
perhaps a decade counter wired to reset on the 3rd step (lower chip count
this way).  I realize that using a counter will provide approximately 33%
pulse width instead of 50%, but I'm not sure if that will cause problems...
so I'd like anyone's advice about this.  

Next, the output of the divide by 3 will run into a 4516.  This will
further divide the signal by 2, 4, 8, 16.  I'll then take the 32nd note
clock (from /3) and all of the 4516 outputs and run them to a few rotary
switches to select the beat division required. (32nd, 16th, 8th, quarter or
half notes)

The output of each rotary switch will run to an 8 (4022) or 10 step (4016)
gate sequencer.  There will be a total of (4) of these gate sequencers.
Each sequencer will have it's own beat division setting allowing one to run
at 32nd notes, while others are running at 16th, 8th, etc.  Also, each
sequencer will have a pattern length setting and each step of the sequence
will have gate on/off switches.  I may also use the carryout function and
allow the sequencers to be arranged in combinations of 8 and 16 step
sequences (options for 4x8, 2x8&1x16 or 2x16).

Finally, the gate outs of each sequncer will run through a shaper to
provide adjustable gate length since the 1/2 note gates will be much longer
than the 16th or 32nd note gates.

I'd also like to tie the start/stop line from the din-sync IC to the reset
line on each counter so the sequence will start at the zero state when the
MIDI clock starts.  I'll probably also provide individual buffered step
outputs from each sequencer on 9 pin D-SUB connectors on the rear of the
unit.  This will allow me to connect external CV circuits later as I need
them.  All of this will be housed in a 2U rack box with pretty blue LEDs :)

I'm picturing this project giving a vast possibility of sequences... I'd
love to hear everyone's opinions.  

Dave Magnuson

Resonant Frequency:
resfreq at hoohahrecords.com
http://www.hoohahrecords.com/resfreq/index.html