[sdiy] Finally - after almost 2 weeks of tuning problems .......

[Rykhaard D.A.M.I.A.N.]

Heh.  Minor, new problem. :P  Haha. :D

I've got all 4 of the rotary switches hooked up again.  I ran into a small
problem.  Whilst all 4 of them cycling away are sounding great - together
they're about 99.5% in tune with each other.  :(

One thought that I had, was to add a trimmer resistor, just before the 1K
resistor to Ground.

I tried a 200 ohm 20 turn trimmer, with an 820 ohm resistor replacing the
1K.  Nope.  Almost, but not quite.

I tried a 500 ohm 20 turn trimmer, thinking that it would help me get that
little bit of extra range.  Nope.  I finally realized that the extra
resistance that I'm putting in, is acting JUST like a TUNING pot! :O  The
frequency ratio is still the SAME right across.  There was no difference in
tuning between the 1st and 12th position on the rotary, whether I had 820
ohms at the bottom, or 820 + 500 ohms at the bottom.
Ahhhh!  So TUNING, WILL work on this version!  :D

But now - how, do I get the ratio set exactly?  My only thoughts so far, are
0.1% each of the 1% resistors, around each rotary.  I THINK, that should
take care of it.  Giving an even division between each step on the rotary.
No?

Also - my trouble COULD be - not having tuned the 1V/octave trimmer in the
Constant Current Source - EXACTLY.  (I'd rushed, on the 1st rotary set up.)
I'm going to go back, and trim it to beat free on 1 trimmer for the 1st and
12th positions, and see where that takes me. :)

Another new trouble - using the LM329 6.9V reference with the Constant
Current Source - is dropping my main output voltage to 1.6V. :O :O  That
only allows me enough resistance to drop the source 1 more volt.  (Unless I
go into -V.  Can I, without troubles??)
I'm wondering if I should move up to a 10V source.  (Which I don't have
anything FOR, at the moment - unless I can do the same thing as the LM329
with an LM723, variable regulator.)

Anyhoo ..... I'm still pleased as punch. :)  Once I have my new maple panels
in, I'll be mounting the PCB to it - and completing the sequencer, finally.
I don't wish to mount it to my prototyping pegboard, as I'll just have to
rip it all out again, to move into the Maple panel. :(  And with the
sequencer; 7 bit divider; S&H; white noise and 2 logic gates on this board -
it'll be a LOT to transfer. :P

Come on maple - hurry up and get here!  :D  LOL

--
Take care,
Warmth and Peace,
Ryk

http://deathlehem.bravehost.com/damian.html - D.A.M.I.A.N.;s webpage - Jan.
0406 update
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