Sine is always going to sound quieter. It doesn't have all the harmonics. Reducing the 330k connected to pin 12 of the 3900 may help increase the volume. It may also cause distortion.
+/-15 is correct. It's an old diagram.
Ken
+/-15 is correct. It's an old diagram.
Ken
--- In cgs_synth@yahoogroups.com, <cgs_synth@yahoogroups.com> wrote:
Ok Ken, thanks for the answer.
Is it normal if the sine output is not so loud as the other outputs ? I'm powering the vco via +/-15v. Maybe i should change some resistors to fix that ? I've seen the schematic uses +/-12v. If not, what should i check ? Changing the two 100K resistors near the 1v/o inputs ?
thanks !
--- In cgs_synth@yahoogroups.com , < cgs_synth@yahoogroups.com > wrote:
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. Evergreenïûÿ is the color of green forever."
[Non-text portions of this message have been removed]