simple clock for Sequencer success!

[Harry Bissell]

If there is only one polarity of power supply... like a single 5 volt or 12
volt...
then you connect it to the other terminal of the supply from the one you hooked
up.

For most 4000 series CMOS, that would be pin 14 to positive supply, and pin
7 to positive supply common (ground).

in dual supplies like +/- 15 volts... the common point between the +/- supplies
is the
(er...) common point (ground, zero volts, etc.)

Maybe thinking of this connection as "common" instead of "ground" will make it
easier.

Sometimes there are more than one common. They can be run separatly and joined
only
at one single (er... common?) point. This is often done to separate noisy
(see...digital) from quiet (see...analog) signals.  The common connection is
often made at the power
supply.

It may be helpful to think of the connection between positive and your circuit
as being
connected by pipes to a source of water... and the negative is the drain pipes.
If you
run the drain pipes all the way back to the master drain, separatly... there is
little chance
of getting a backup in the opposite pipe...

Another side of this... the circuit is not really connected to "ground" or
"common"... it
is connected with "pipe".  Make that pipe too small, and when one apartment
(circuit)
flushes its toilet... the water level bounces in everyone else's toilet... This
says that the
drain pipe should be really BIG so that this either does not happen, or is
measurably
small.

Philosophical Question:  If I pour a single glass of water into the ocean...
does the ocean
level rise?  Answer... OF COURSE it does... but the effect might be so small
that you will
never notice except with the most sensitive instruments.  And it is VERY
unlikely that you
will cause a flood in a harbor up (or down) the coast.

But what if you pour the same glass of water into a shotglass ???  Does the
level rise...
you bet, you WILL notice... and you will fvck up your tablecloth...

So be as careful with "common" or "ground" as you would with any other
conductor. Do
not expect tiny, haphazard wires to give proper results.  The ultimate is the
"star" ground..
where each component has its own wire (pipe) leading all the way back to the
master
common (drain). next best is to separate the high current runs and the low
current runs...
( separate wires or planes).

Ground (or common) is supposed to be like the ocean. You should be able to dump
as much as you want into it, without ever changing its level or filling it up.
In real life... ground
is really like a lake, and you need to be careful where you dump the water into
it.

H^) harry

I will let someone else that the "good clock" question....

Eduardo Saponara wrote:

> I'm wondering if anyone knows where I could find a simple schematic for a
> suitable tempo clock input for this simple sequencer?
>
> Ok, now prepare for a really beginner qustion.  on schem diagrams,  what do
> you actually do when the symbol says to ground?  copper wire to where?  I am
> really really new to this and have only built simple kits.  tutorial site
> url's would be appreciated as well.
>
> thanks
>
> ed
> -----Original Message-----
> From: Hairy Harry <paia2720 at hotmail.com>
> To: mitch at sirius.com <mitch at sirius.com>; efm at xavax.com <efm at xavax.com>;
> synth-diy at node12b53.a2000.nl <synth-diy at node12b53.a2000.nl>
> Date: Saturday, October 14, 2000 2:53 AM
> Subject: Re: Sequencer success!
>
> >Hi Mitch.
> >
> >Yes... you could put a resistor in series with the high side of each
> >pot...
> >
> >~or~
> >
> >CMOS can run on voltages from about 3 to 18 (MAX) volts... if you
> >wanted less range you could slap a 5V regulator on the supply comming
> >into the PCB.  Or any other voltage you wanted between 3 and probably
> >12V (assuming you use a 15 volt supply...).
> >
> >H^) harry
> >
> >
> >>From: Mitchell Hudson <mitch at sirius.com>
> >>To: EFM Synth DIY <efm at xavax.com>, Synth DIY
> <synth-diy at node12b53.a2000.nl>
> >>Subject: Sequencer success!
> >>Date: Fri, 13 Oct 2000 04:37:07 -0700
> >>
> >>     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
> >>
> >
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