[sdiy] sequencer ideas

[Tavys Ashcroft]

I have a pair of Boss RSD-10 sampler/delay units, and I want to make 
a sequencer for them.  The really nice feature about them is the 
keyboard jack on the back that takes a square wave input and uses 
that frequency to determine the playback rate of the sample.  So I 
can record a sound into it and play it back at, really, any rate (it 
says two octaves, but I get much more than that out of it...down to 
the crunchy rumbles).

I want to make a sequencer (8 or 16 step) similar to the one here:

http://www.webdevils.com/schematics/SEQ8.jpg

But I plan on having each step have it's own 555 osc with both pitch 
and on time controls.  I want to be able to have little short blips 
down to the full length of the step.  Is this just a matter of using 
a pot to set the RC time constant of the 555, or will I need a second 
one in there for that?

The RSD-10 also has a gate input along with the keyboard input, so 
maybe I should utilize that for the triggering, using a separate 
one-shot 555?

Also, how difficult is it to string together two of these 8 step 
sequencers to make one 16 step..or is there a better way of doing it?

-Tavys