Sequencer success!

[Eduardo Saponara]

I am thinking about trying to build this sequencer as my first variboard
project,  but I don't know the first thing about how to lay it out.  can
anyone give some suggestions?  you guys with the circuit mapper programs
maybe?  any tips appreciated.
----- Original Message -----
From: Mitchell Hudson <mitch at sirius.com>
To: EFM Synth DIY <efm at xavax.com>; Synth DIY <synth-diy at node12b53.a2000.nl>
Sent: Friday, October 13, 2000 9:37 PM
Subject: Sequencer success!


>     So the beginners have done it again! Yep they've found the simplest
> most basic 8 step sequencer they could find, put it together and it
> mostly works! Two IC's, one transistor and three resisters not counting
> the front panel components.
>
>     I do not remember where I found this schematic, if anyone recognizes
> this one let me know. I put a copy of it here
>
> www.webdevils.com/schematics/SEQ8.jpg
>
>     I put this together on a perfboard from radioshaock and made a front
> panel from a two unit frac panel. I left some room on the panel for one
> more knob and a couple of extra jacks so I can add a clock at a later
> date.
>
>     There are a few things that need improvement. It has one small
> problem with the up/down switch. When switched the sequence runs
> backwards and stops. Not sure what the problem is, I am assuming of
> course that the sequence should not stop but repeat backwards when the
> switch is down. everything runs fine in the forward direction.
>
>     The output seems a little high, I am assuming there is a range of +
> a small amount of volts up to +15V. Initial tests using the sequencer to
> control my VCO, through the v-oct, seem to show that the knobs are only
> useful for about half of their range. The rest of the range being too
> high or too low depending on the initial pitch of the VCO. Seems what I
> really would be looking for would be a range of 0 to +10V? I am thinking
> there is probably a way to scale the output down a bit with a resister
> maybe. Though for some reason my beginner instincts are telling there
> should be an op-amp involved because these things seem to end up in
> everything and this circuit doesn't have one, yet.
>
>     I had the idea that if I built a clock with two outs that flip
> flopped. I could build a second simple 8 step sequencer and clock each
> from one of the outs of the clock and get 16 steps out of the two...
>
> Thanks
>
> --M
>
>