I just started my coffee, and haven't built my cgs65 at all, but I'm
still thinking that you would only need one 330K resistor between
the signal grid and the actuator of the switch.
On 3/29/08, basdbg963 put forth:
>--- In ModularSynthPanels@yahoogroups.com, James Elliott
><johans121@...> wrote:
> >
> > Now, it very well may be possible to use a SPDT switch to do this,
> > however upon a novice's first (or second, third, fourth) glance it
> > seems that the jumper switches between to pins on the tube - so I
> > don't know that a SPDT will work without some other circuit voodoo
> > magic. I'm writing this at work so I can't necessarily verify what
> > I've just said at this moment....
>
>Since I'm building one this evening, thought I'd follow up.
>There is a bit of voodoo. It looks like Ken intends for
>pin 4 of the tube to be at the same voltage as the 330K
>bias resistor so the 'outside' of both options are actually
>connected on the board. (You should be able to follow this
>on the PCB with little effort.) The voodoo then is to send
>the three pads involved in the jumper option (i.e. not the
>330k resistor option) to the SPDT switch. Then solder the
>330K resistor from either of the two left pads (they're
>connected) to the center pad of the jumper set. (It will
>actually work better if the resistor is put in first in
>vertical position giving you a solder point for the middle
>wire of the SPDT run.) The voodoo makes it a bit harder
>to try tweaks but that's the tradeoff...