[sdiy] Varying gate lengths (using a 4017 counter) for a simple sequencer?

[fmg]

Julian,

This is a clockless (autotrigered) 4017 sequencer with individually
adjustable step-lenghts.
Not for percussion or rythmic music (but able too). I made it just
for ocasionally solos.

This is a one year frozen project. I made a functional proto but
there are still "bugs" in the circuit that won't let it run as I
draw it. I used LM324 as comparator for convenience then but this
should be changed. Hope one of these days I found enough time to
complete it (put it in a box, draw the correct schematics, etc)

Basically each 4017 output charges a capacitor through a pot
(adjustable time) until a level where the comparator "clocks"
the 4017 repeating a new cycle with the next step.
A single 4017 block gives you 8 outputs. Blocks can be reseted,
do loops, be "shocked" (externally clock forced), or serialized
(cascade) for longer sequences. I also used the 4017 outputs as
gates (with FETs - not in the schematics) for individual notes
fx (vibrato, pitch bend)

Building 8 or 10 blocks that can be connected in parallel
or serial or forming groups could bring interesting results.

The schemo below is a 2 cascaded blocks (16 steps) seq.

Hope it helps

http://www.geocities.com/eqys_p/eqys_q.pdf

Fabio
.

Julian wrote:
> 
> Hi there,
> 
> I'm messing with a 4017 decade counter, as a simple sequencer.
> 
> Is there a simple way to take the regularly spaced outputs (gates) from
> this, and vary the length of them - i.e.. both make them shorter then they
> actually are, and longer then they actually are?
> 
> Basically what I'm thinking is a simple sequencer, like the one mentioned in
> the 'simple sequencer' thread earlier, but with control over the gate times
> too.
> 
> Ken stone's project using this chip offers a solution using switches to swap
> between the gate signal and a set, shorter, pulse, but what id really like
> is a completely variable time that can also be different for each step,
> ideally being able to even have overlapping gates (i.e.. longer then one
> clock cycle) although, i guess this isn't nearly as important as being able
> to shorten the gate individually for each step.
> 
> So, any suggestions? (in relativly novice terms please - im still quite near
> the bottom of the curve ;)
> 
> Thank you,
> 
> Julian