This could be due to a grounding problem. I suggest double checking the
grounding back to the power supply first. Then check that all the
places that are supposed to be grounded in the VCO actually are
grounded. It could also be due to ground loops, that can cause
"parasitic" oscillations, unwanted high frequency oscillations in
unexpected places. If you have a scope, you should look for parasitics
sitting on the VCO outputs. Ideally, grounds should follow a star
pattern, with all grounds connecting back to the power supply connector
in a direct manner. One way to troubleshoot is to change one or more
ground wires and see if the problem is fixed. By "change" I mean adding
a separate ground wire for each jack, etc..
Look closely for bad solder joints, too, on the entire PC board and all
off-board connections.
Richard Brewster
http://www.pugix.com
Rykhaard D.A.M.I.A.N. wrote:
grounding back to the power supply first. Then check that all the
places that are supposed to be grounded in the VCO actually are
grounded. It could also be due to ground loops, that can cause
"parasitic" oscillations, unwanted high frequency oscillations in
unexpected places. If you have a scope, you should look for parasitics
sitting on the VCO outputs. Ideally, grounds should follow a star
pattern, with all grounds connecting back to the power supply connector
in a direct manner. One way to troubleshoot is to change one or more
ground wires and see if the problem is fixed. By "change" I mean adding
a separate ground wire for each jack, etc..
Look closely for bad solder joints, too, on the entire PC board and all
off-board connections.
Richard Brewster
http://www.pugix.com
Rykhaard D.A.M.I.A.N. wrote:
> Here's a new weird experience for me:
>
> I've got VCO V0.2 about 98% completed. (Still needs 1V/octave
> tuning). In wiring up all of the controls and jacks to the front
> panel (wood, as all of mine are), for the first time ever in any of
> 100's of modules that I've built over the years, I have this module
> acting as an ANTENNA! :O
>
> The closer that I put my hand to either of the 2 tuning knobs or the
> pitch CV Amount knob, the higher the pitch of the VCO becomes. ????
>
> Has anyone else ever had this kind of trouble with any module?
>
> The one new thing that I've done with this module, that I've never
> done before - is wrap all of the wiring from the PCB, around other
> wires to / from the PCB. I figured I could do that to keep all of the
> wiring as neat as possible, instead of using cable ties, to hold them
> all together. Could THIS be the cause for picking things up from my
> own touch?
>
> When I get ready to do the 1V/O (Mooging? ;) ) today, I thought I
> would unwrap each of the 3 voltage feeds (Tune, Fine, CV) from the
> wrapped wires to leave them free-hanging, to see if this stops things.
>
> Another difference that I'm surprised by: this VCO is highly affected
> by the voltage swings in 1 of my 2 LFOs. (My previous Tom Gamgle
> VCO4D and Ian Fritz mini-VCO) aren't affected at all.
> Both of them though - have 100uF bypass caps on the power inputs to
> their boards. I'm going to try increasing the bypass cap values on
> the VCO V0.2 board to 100uF as well as at least 1 x 100nF each. Also
> - I'll check my 2 LFOs to see if they have proper bypass caps at their
> quad opamps as well.
>
> Thanks to any possible solutions to what I've typed, above. :)
>
>
>