Sequencer Update

[jhaible]

 I originally
> planned on using John Simontons 4-bit convert 
> http://www.paia.com/ek7.htm

Looks interesting !
I just wondered how to build a logic for 16 comparators ...
but this might be an alternative! Any drawbacks of
this design? John?


> My last idea involves creation of another module of which I have
> never seen an implementation of. A "random probability select".
> A gate input will trigger the module to randomly select a channel
> and output an associated voltage. Each channel would have two
> controls. One control is the voltage to be output. The other control
> determines the probability that this channel will be selected.

This might be useful. I think the OB-8 has a feature in its arpeggiator
that even in Random mode the first note you enter will have a higher
probabillity than the others. Easy in software, but probably not to
be included in my hardware only sequencer.

> Well, I have probably too many ideas for a single design. I would
> be very interested in your designs. I would also be interested
> if you decided to do something similar to the ASM-1, w/ circuit
> boards and/or faceplates. I know many on the list are interested
> in a good sequencer.

I think I won't make a PCB myself, but maybe a 3rd party may join 
in here. I will have my frontpanel made from Schaeffer Apparatebau,
and I will offer the design data to anybody who wants them for
private use.

But it's still a looong way to go before I can think of that.

Update:
I have just finished the "core" of the sequencer, that is up/down
counter, skip and random control, reset and preset, VC clock
and VC gate length. It's pretty much the ARP sequencer with
an improoved random generator and up/down counting.
Just a test board with 4 LEDs to monitor the binary output.

Next steps:
(2) A control board.
I like the ARP seq's way of handling start, stop, and step functions.
Use 2 buttons for start/stop, ore use one and toggle between the states.
Use an extarnal gate to trigger functions, or to *gate* the on/off
function.
I guess I will replicate that, too. And duplicate this whole section
for up/down control.

(3) The "vertical" stuff.
I looked at the Serge schemos again, and boy, do *they* have implemented
a wealth of functions ! The inputs for all these functions are very simple,
compared to the ARP (debouncing etc.). I wouldn't leave it this way ...
4 complete rows of 16 steps are a lot of potentiometers - to buy, to put
on a front panel, and to tweak. I really had something like 2x8 or 2x12
in mind when I started, and not 4x16 ...
I am not sure what I will do in the end, but the use of a separate vertical
clock has something for it. So at the moment I tend to go 4x8 or 3x8.
A skip function for the vertical clock would be useful. And the
possibillity
to derive the vertical clock pulses from one of the horizontal gate busses.
For comfortable live use, I have a special "delayed row selection" in mind:
When I want to change from one sequence to the next I hit a button,
and then this "change request" is stored in a latch until another event
takes place, like end of one sequence, or step #N in a sequence. This
should be fairly easy with Gate busses, too.

Ok, that's all for now. Thanks again for all suggestions (and keep them
coming 
in ...), they are all very helpful !

JH.

PS.:

Any Ideas where to get these highly ergonomic pushbuttons that several
commercial
Sequencers have built in? (Korg SQ-10, for example)