[sdiy] 4069 vco gives v+ noise?

[Karl Ekdahl]

I use the same pinning as in the schedule you sent but
it's still giving noise (in the v+ line). The noise
seems like a 50hz wave with some minor disturbances
riding on it that seems to be the osciallating tone. 

The minor noise can at high frequencies be eliminated
trough adding a 10uF cap at the v+ line but I can't
reduce the major noise (the probable 50hz) without
putting a resistor inbetween ground and gnd pin on the
4069. And that - as i said - makes the square out die.

The odd thing is that the noise only occurs if i add
more modules to the same powersupply, for example a
ASM lfo. The powersupply should be able to drive both
modules (at least i think so) without any
distrubances. It's based aroun 78xx, 79xx and 6800uF
caps and uses the standard layout found in most
powersupplies.

/Karl

 --- Scott Gravenhorst <music.maker at gte.net> skrev: >
René and I discovered that there is a sensitivity to
> which inverters
> are used for what purposes.  I found two
> configurations that did not
> work correctly.  When I hooked mine up like René's,
> it began to work
> properly.  I didn't notice noise on ground, rather,
> I had a burst of
> grass occuring on the PWM output when it should have
> been a single
> solid edge.  René was able to reproduce what I saw
> by hooking it up
> my "wrong" way.  Your problem might be related.
> 
>
http://home1.gte.net/res0658s/fatman/VCO_pwm_tri_suboctave.html
> 
> See the center portion of the schematic with heavier
> lines.
> 
> This is a linear version of the same VCO showing the
> pinning that
> works.  The one I built works very nicely.
> 
> 
> =?iso-8859-1?q?Karl=20Ekdahl?= <_nial_ at yahoo.com>
> wrote:
> >Hello everyone, i've built René Schmitz 4069 vco
> and
> >stand alone it's working perfectly. But while
> adding a
> >few modules to the same powersupply the ground line
> >starts "wobbling". 
> >
> >Through my limited electronics knowledge i've
> >recognized that if i put a 100k resistor inbetween
> >ground and gnd pin on the 4069 i can reduce the
> noise
> >but then the square out stops functioning. 
> >
> >Does anyone have any idea on why there's ground
> noise
> >and how to prevent it?
> >
> >thanks
> >
> >/Karl
> >
>
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>
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