Seq2 Preview - PCB Project

[Gene Zumchak]

tomg,

    It seems to me (who in another lifetime designed something called a Moog 960 sequencer using RTL
because TTL was still too expensive and CMOS wouldn't exist for another decade) that the ONLY was to
make a sequencer is with a micro.  The 960 had eight events, although you could skip any event for
fewer events.  There were three rows of pots for three control voltages out.  The third row could be
switched into the LFVCO that  ran the sequence to control rhythm.  There were buttons for manually
selecting each event and triggers for envelopes.  Considering that nobody knew what a sequence was or
what it should do and the fact that I had never designed anything in my life, it probably wasn't so bad
a design.

    Today, I would use far fewer pots, and D/A's and A/D's.  Your sequence could be from 2 to
whatever.  You could arithmetically add sequences so that you could create an arpegio with sequence 1
and then move that sequence up and down with another sequence.  The sky is the limit.  Your imagination
is the limit.  The board is small.  The number of parts are small.

    In the future I plan to have an HC12 development board available for prototyping such projects.  It
will have two serial channels so that one can serve as midi.  A MIDI to CV module would be a typical
application.  But you could also have a MIDI controlled sequencer, a SUPER LFVCO, etc.

    What you are describing using descrete logic seems a little simple and very limiting.  I did the
960 thirty years ago.  The world has changed a lot since then.  I have not lost my love for analog, but
I started as a digital guy (which is why I made the 960 and not Bob) and I'm still a digital guy except
PLD's and micros is the way to implement digital these days.

    Probably you should go ahead and make your sequencer as you envision it.  Maybe some day in the
future I'll collaborate and a digital one.

Gene Z.



tomg wrote:

> I started work on the Sequencer 2 today. I had been thinking about the 74LS164
> as a sequencer chip, I think I saw this in the Super Sequencer. Anyway the more I thought About It
> the less I liked the idea of using TTL. So we are out walking, the wife says "you gota move to
> live" so we walk about two miles a day, jog some mostly walk....and I'm thinking about this
> sequencer and telling her what I want it to do and she's listening and it dawns on me the way I
> need to go with this.
>
> Everybody wants 16 steps, nobody wants to give up any of the functions the seq1 has. So I decided
> to use a 4516 for the sequencer chip. This has all the important pins plus the up/down count built
> in, this is really neat!! It'll stop on a dime and go the other way! And that's good because I'm
> going to have to add a flip flop to supply the carry out function to stop the seq2 thats running
> and start the next one in the chain.
>
>  The problem is it doesn't have sequential outputs, it has BCD outs. So I used 4051s to drive the
> actual sequencer outputs. This worked out really well because using the inhibit pins on the 4051s
> lets you split the 0-16 sequence in two parts 0-8 and 9-16. I will add (maybe) a 4017 to each half
> that will allow you to set how many times (1-10) you wish each half to play before flipping back to
> the other. This is a little redundant as the idea is to have one sequencer trigger another that
> triggers another...that triggers the first one in the chain, and it starts all over again. But It
> would be cool to be able to have two sequences in one... Maybe I should just add a counter to each
> sequencer to determine how many times it plays before going to the next sequencer...Hummm we shall
> see. Any Votes?
>
> I think I prefer to use one sequencer per sequence and add a counter to determine how many times it
> plays before starting the next module. What do you think is 1-10 enough?
>
> Despite my efforts to avoid it I will have to add a 4066/16 switch to each glide pot and switch it
> in/out with the channel output transistor to keep off channels from affecting the glide. This is
> not shown.
>
> Comments? Suggestions? Wishes?
>
> Do you want a small cheep board with a little wire-flying or a big expensive board with mounted
> pots
> and leds? This would require everybody buy the exact pots used to layout the board. I vote for the
> cheep board myself.
>
> http://www.mindspring.com/~vco/cbook/pics/seq2.gif
>
> VCO4 UPDATE...
>
> The Vco4 boards may be ready by Friday. They aren't dew until next Monday, but he said call. If
> they are ready I should be able to ship as soon as Saturday.
>
> -tg