[sdiy] components, smd and pcb

[jhaible]

>    Glad to see that others are joining the SMT bandwagon!
[...]
> > ICs should be SMD, resistors should be ordinary.
>
>    I don't agree with this.  Even when considering the fact that you may
> be limiting yourself to a single-sided board, there are many
> times where a SMT resistor makes sense.

I'm sure you are right here. I'm just starting again with PCB stuff
after many years, and it's my first time to use SMD at all, so I'm
sure there's a lot more for me to discover. At the moment, I have
a complete E24 series of normal resistors, plus one decade of
E96, so I don't want to buy all that in SMD as well. For me, this
is just a hobby, after all. I can always mount an ordinary resistor
vertically, with 2.54mm distance, so it does not take up so much
more space than a SMD resistor. (I still have to pay for the holes,
though.) At the moment I really enjoy using resistors horizontally,
routed all over the SND chips on the other side. That's fun, because
it makes routings possible that I never dreamed of.

>    Why not keep the SMT parts on the "right side" and put your resistors
> on "the other side"?  It might make it easier to keep track of things?

Very good idea !!

>    One question, Juergen, will your boards be compatible with the
> originals?!  I would be _very_ interested in that!

No, not at all. I have simplified the oscillator circuits. For one VCO
+ 4 octave saw dividers + 4 octaves transpose circuit + triangle / pulse
waveshapers I only need this:

1 CD4520 (the two dividers)
7 bipolar transistors (VCO core and waveshapers)
1 CD4066 (transpose switches)
1 TL084 (replaces all the selected SK30's in the original, and most
                of the coupling capacitors)
1 FET (unselected)

While it's not compatible to an original PS-3100, the good thing is that
it will go on standard double europa cards with two DIN41612 connectors
which are mounted into a 19" 6U rack frame. So building more than one
will be not entirely impossible this time.

But it's all just in the very beginning. I will first build one VCO card
(6VCOs), and see what it costs and how good it works. Then I'll decide
wheter to cancel it all, to build a second card (PS-3100), or to build
three more cards (and go for PS-3200).
If I say "PS-something", I just mean the general route. 2 oscillators
per voice will not mean patch storage, nor the lack of a 3100's
resonators. I still have to decide if I'm using the original ADSRs
or something of my own, for instance.

Just in case I would really go for patch storage (gladly, I don't have
to make that decision now; it can be added later) -
Dou you know a source for 10k lin pull-pots ?

JH.