Square out is a different issue altogether. No square out happens when the PWM voltage is outside the range covered by the sawtooth. The CV issue is a problem somewhere in your input mixer, where you seem to have excessive gain.
--- In cgs_synth@yahoogroups.com, <cgs_synth@yahoogroups.com> wrote:
yep, i didn't forget it. The fact is i can see on my scope the saw out, the sine one, but i can't have square out. Tomorrow i'll desolder all the pots & out, and change my transistors & tempco... we'll see what happens !
--- In cgs_synth@yahoogroups.com , < cgs_synth@yahoogroups.com > wrote:
Have you fitted the 1k tempco resistor (or a regular 1k resistor in its
place)? When I built a similar VCO using discrete transistors instead of an
LM394, I forgot to place this resistor, and the oscillator didn't work.
This is the resistor that is supposed to sit over the LM394 for thermal
coupling, which is why I forgot it when using transistors.
On 2 September 2013 16:15, < lofideadbeat@... > wrote:
> **
>
>
> Well, here are my test. Seems to be a bit weird. I've multimetered my ics
> when my pots where center positionned
>
> i can see that if i approach my fingers to the pots or some parts it's
> altering the sound...
> I've rechecked all my links & solders...
>
> IC1 / TLO72
> 1 : -1,55v
> 2 : 0
> 3 : 0
> 4 : -15
> 5 : 0
> 6 : 0
> 7 : 0
> 8 : 15
>
> IC2 LM394/2N3904
> 1 : 0
> 2 : 0
> 3 : -0,5
> 4 : nc
> 5 : nc
> 6 : -0,5
> 7 : 0
> 8 : 0
>
> IC3 : TLO72 near the unicorn
>
> 1 : 0
> 2 : 0
> 3 : 0
> 4 : -15
> 5 : 0
> 6 : 0
> 7 : 0
> 8 : 15
>
> IC4 / CA3140
>
> 1 : -15
> 2 : 0
> 3 : 0
> 4 : -15
> 5 : -15
> 6 : 2
> 7 : 15
> 8 : 3,5
>
> IC5 / LM3900
>
> 1 : 0,1v
> 2 : 0,4
> 3 : 0,5
> 4 : 0,15
> 5 : 0,15
> 6 : 0,55
> 7 : 0
> 8 : 0,53
> 9 : 2,2
> 10 : 2,2
> 11 : 0,5
> 12 : 0,37
> 13 : 0,37
> 14 : 15
>
> IC6 / LM311
>
> 1 : -15v
> 2 : 2,2
> 3 : 4,96
> 4 : 15,3
> 5 : 15
> 6 : 15
> 7 : -15
> 8 : 15
>
> IC7 / TLO72
>
> 1 : BTW +6 & +12
> 2 : 0
> 3 : 0
> 4 : -15
> 5 : BTW -2 & +2
> 6 : -0,3
> 7 : BTW -8 & +12
> 8 : 15
>
>
>
> --- In cgs_synth@yahoogroups.com , <lofideadbeat@...> wrote:
>
> Well, thanks for your answer Ken... I think my problem is somewhere else,
> but can't see where.
>
> If i use my sequencer on the vc fm, i can modulate the vco.
>
> If i apply the same cv output to the cv in, my vco doesn"t respond. If i
> apply the cv output to the 1v/o in, nothing. If i apply 1v to the 1v/o
> input, nothing..
>
> I've got 0v on ic1 pin 7, when i've got my tune and freq pot in center
> position, but if i try to move them, they don't modulate a lot ( maybe from
> 11 to 1 oclock).
>
> thanks for any help. I gonna check all the ics voltages and send it there,
> maybe it'll help !
>
>
>
> --- In cgs_synth@yahoogroups.com , <sasami@...> wrote:
>
> If the span trimmer is not right, the VCO may be too sensitive to CV and to
>
> the tuning pot.
>
> Ken
>
> >Hi Everybody ! That's my first post here, as after building several
>
> modules, i think i've got some problems to fix on my cgs48. I've
>
> used a 2N3904 matched pair instead of the LM394. I think that my vco is
>
> working, but i can't really use the initial freq pot. It must be always
>
> in its center position if i want to hear the vco. Is it normal ? I only can
>
> tune the vco using the fine pot... In a post here, i've seen i could
>
> change the 1m resitor to a 2,2m one, and i did this change, but it just
>
> affect the fine tune pot, no the intial one. What should i check ? thanks
>
> for any help ! jean
>
> >
>
> >------------------------------------
>
> >
>
> >The CGS Modular Synth home page: http://www.cgs.synth.net/
>
> >Yahoo! Groups Links
>
> >
>
> >
>
> >
>
> >
>
> __________________________________________________________
>
> Ken Stone sasami@... otherunicorn@...
>
> Modular Synth PCBs for sale < http://www.cgs.synth.net/ >
>
>
>
--
/Ove
Blog: < http://blog.gg8.se/ >
"Here is Evergreen City. Evergreen is the color of green forever."
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