[sdiy] TH XR2206 VCO tune pot

[David G. Dixon]

> I understand why you don't want to put those resistors in, it would be an
> ugly mod.

Not if you use something like a pcb-mounted pot and a pot chiclet.  You can
even etch your own or use a small piece of perfboard for this purpose.  The
resistors can then be put on the chiclet.  You can even add to the input
resistor this way, by putting additional resistance on the centre tap.

When I lay out a PCB for any circuit involving a tuning pot (like the
2164-based VCO I just built --  more on that later), I always provide space
on the board for resistors between the pot ends and the rails.  If I want to
hook the pot directly to one or both rails, then I simply put jumpers in
where the resistors would go.  This works very well for me.  If I decide
that I want to change the range later, I just suck one off and replace it
with the appropriate resistor.

Incidentally, using 0.1" connectors for all panel connections is also very
helpful, as I can just unplug the board and remove it to make modifications
without taking the entire module apart.  It took exactly one PCB hardwired
to a panel for me to learn this lesson!