[sdiy] gate sequencer (& chips)

[Rafael_Cohen at prusec.com]

Hey everybody,
Thank you so much for all the generous welcome & replies!  I decided to
order the Thomas Henry book.  I'm probably going to get a few of the basic
kit boards from Ken Stone including a gate sequencer.  I'm sure I will be
writing again in the next months as I start "getting my hands dirty."

One thing I am curious about is the different kinds of chips out there.
Just from the responses I got yesterday regarding different chips I poked
around Radio Slack after work.  They have several different kinds of 555s.
Also mouser has about a dozen different chips called "1N4148" so I'm a
little baffled as to getting what I need.  I guess I will wait until I get
some of the actual schematics and see specifically what is needed at that
point.

Thanks again everybody, feel free to keep the ideas coming, re: particle
accelerators or not ;  ) !

Rafael
Brooklyn, NY



                                                                                                                                       
              "john mahoney" <jmahoney at gate.net>                                                                                       
                                                          To:                                         <synth-diy at dropmix.xs4all.nl>,   
                                                           <Rafael_Cohen at prusec.com>                                                   
              Thursday November 18, 2004 08:29 PM         cc:                                                                          
                                                          Subject:   Re: [sdiy] gate sequencer                                         
                                                                                                                                       




----- Original Message -----
From: <Rafael_Cohen at prusec.com>
>
> I want to build a gate sequencer.  I'm curious how difficult it
would be
> and where I would start.  I was thinking 2 rows of 16 toggle
switches with
> LEDs to indicate on/off status.  In it's simplest form, that's
pretty much
> it.

I'd suggest Thomas Henry's Superseque, which I am accumulating the
parts to build, myself. Unlike most DIY sequencers, which are based on
the 4017 (a 10-step device), the Superseque pairs a 4516 up/down
counter and a 4514 1-of-16 decoder to create a 16-step sequencer. You
can get the plans in 2 ways:

For $25, buy Henry's book "Electronic Music Circuits: The Reprints,"
from his company:
    http://www.midwest-analog.com/catbooks.html

Or for $10, you can get the June 1985 issue of Electronic Musician in
which the Superseque originally appeared:
    http://images.industryclick.com/files/33/back_issue_list.pdf
You want the last issue on the list -- Volume 1, Number 1. (Others
will remember that EM was originally published by PAiA under the name
"Polyphony.")


> With a clock input and two ouputs for the gate signals.  I don't
need
> to program note/cv values, just gates on/off in time.

So far, so good, but...

>  The only other
> feature I'm itching for is a micro-timing knob for each step to push
the
> signals a little bit early or late.  I have this sinking feeling
that might
> make the project about four times as complicated.

Yes, this complicates things! Conventional wisdom is to use a row of
pots, one for each step, and use those pots (or a CV that they
control) to control the clock rate; this idea has already been
presented to you. But that would vary the length of each step, which
isn't exactly what you are asking for.

Let me assume that you need 3 variations: early, on-the-beat, and
late. Here's one possibility:

Build 2 sequencers that work together: a 16-step master and a 3-step
slave. Build the slave sequencer from a CD4017 (or CD4022). Then build
a Superseque as the master. Well, this is getting complicated, and
I've got to run... sorry to bail on you! Maybe you can elaborate a bit
on the behavior you want from the sequencer, such as how many
variations are needed, and what about the gate duration?


> Right now, I'm not even
> trying to worry about pattern length, pattern direction, any of
that.  I
> really have no idea how to go about it.

The Superseque handles variable length as well as pattern direction.
Pattern length is actually quite simple using the 4017 or the
Superseque.


> "I have a frying pan and a coat hanger, please tell me
> in monosyllables how to build a particle accelerator..."

Ah, wrong list -- try High-energy Physics DIY (HEPDIY). ;-)
--
john