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

[Peter Grenader]

there's an easy. albeit somewhat clunky way:

1) Set up a pot/time variable internal one shot, like the 4538, which gets
it's trigger from the incoming clock of the sequencer.

2) stick an AND gate at each of the gate outs of the sequencer

3) On one side of the AND, put each stage's gate out

4) on the other side, buss the one shot's output

there ya go.

Tiis will allow for outputs SHORTER than the gate signal would be otherwise.
if the one shot is dialed in longer than the gate lasts, it won't matter
because the AND gate takes care of that.  But what makes this clunky is that
depending on the speed of your sequence, you may have a lot of dead zone on
the pot.

If you want EACH STAGE to have it's own PW, forgo the AND gates and put a
separate 3538 at each stage output and this will allow you to set them
longer than the gate would be otherwise. You'll need a pot for each stage
now or one pot driving a slew of vactrols or OTAs. Remember, the pot in this
oneshot circuit's in an r/c, so it can't be bussed around directly.  The
cool thing about dong this is it would be quite easy to also add a VC Input
to adjust the width of the gate - kind of a new twist.

hope this helps,

P 

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
> 
> 
> 
>