Cgs synth

>I got a working scope today, and the saw out of the VCO is very
>strange. Rather than /|/|/|/| it goes -\-\-\-\. That is the best I
>can do, but the 1st example should be a normal saw, and the 2nd
>example, whats going on is that it goes straight up, has a flat top,
>then slopes down. I tested my paia VCO and the shapes are fine, so Im
>sure Im using the scope correctly.
>Any idea what could be causing this?
>
>Thanks,
>Scott
>
>
>
>
>
>The CGS Modular Synth home page: http://www.cgs.synth.net/
>
>Yahoo! Groups Links
>
>
>
>
>
>
>
>

--- In cgs_synth@yahoogroups.com, sasami@... wrote:
>
> Usually caused by the signal hitting a power rail and running out of
> anywhere to go. It's what i'd expect to find if an offset resistor
was not
> soldered in propperly (or the wrong value), or some other voltage
> determining part. The name givven to this is "clipping".
>
> Ken
>
> >I got a working scope today, and the saw out of the VCO is very
> >strange. Rather than /|/|/|/| it goes -\-\-\-\. That is the best I
> >can do, but the 1st example should be a normal saw, and the 2nd
> >example, whats going on is that it goes straight up, has a flat top,
> >then slopes down. I tested my paia VCO and the shapes are fine, so Im
> >sure Im using the scope correctly.
> >Any idea what could be causing this?
> >
> >Thanks,
> >Scott
> >
> >
> >
> >
> >
> >The CGS Modular Synth home page: http://www.cgs.synth.net/
> >
> >Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
> >
> _______________________________________________________________________
> Ken Stone sasami@... or sasami@...
> Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
> Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>
>

> >
> > Usually caused by the signal hitting a power rail and running out of
> > anywhere to go. It's what i'd expect to find if an offset resistor
> was not
> > soldered in propperly (or the wrong value), or some other voltage
> > determining part. The name givven to this is "clipping".
> >
> > Ken
> >
> > >I got a working scope today, and the saw out of the VCO is very
> > >strange. Rather than /|/|/|/| it goes -\-\-\-\. That is the best I
> > >can do, but the 1st example should be a normal saw, and the 2nd
> > >example, whats going on is that it goes straight up, has a flat top,
> > >then slopes down. I tested my paia VCO and the shapes are fine,

> > >sure Im using the scope correctly.
> > >Any idea what could be causing this?
> > >
> > >Thanks,
> > >Scott
> > >
> > >
> > >
> > >
> > >
> > >The CGS Modular Synth home page: http://www.cgs.synth.net/
> > >
> > >Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> >

> > Ken Stone sasami@ or sasami@
> > Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
> > Australian Miniature Horses & Ponies

> >
>

>Sorry for the basic question, but which are the offset resistors? The
>ones around the tl072 that outputs to the saw out?
>
>If so, I should mention I am using a 270k instead of the 240k, and a
>560k instead of the 330k, which is what the elby instructions said to
>do. I think everything else is per the schematics.
>
>
>--- In cgs_synth@yahoogroups.com, sasami@... wrote:
>>
>> Usually caused by the signal hitting a power rail and running out of
>> anywhere to go. It's what i'd expect to find if an offset resistor
>was not
>> soldered in propperly (or the wrong value), or some other voltage
>> determining part. The name givven to this is "clipping".
>>
>> Ken
>>
>> >I got a working scope today, and the saw out of the VCO is very
>> >strange. Rather than /|/|/|/| it goes -\-\-\-\. That is the best I
>> >can do, but the 1st example should be a normal saw, and the 2nd
>> >example, whats going on is that it goes straight up, has a flat top,
>> >then slopes down. I tested my paia VCO and the shapes are fine, so Im
>> >sure Im using the scope correctly.
>> >Any idea what could be causing this?
>> >
>> >Thanks,
>> >Scott
>> >
>> >
>> >
>> >
>> >
>> >The CGS Modular Synth home page: http://www.cgs.synth.net/
>> >
>> >Yahoo! Groups Links
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> _______________________________________________________________________
>> Ken Stone sasami@... or sasami@...
>> Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
>> Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>
>>
>
>
>
>
>
>
>
>The CGS Modular Synth home page: http://www.cgs.synth.net/
>
>Yahoo! Groups Links
>
>
>
>
>
>
>

--- In cgs_synth@yahoogroups.com, sasami@... wrote:
>
> The 240k is the offset resistor. it sounds like the resistor you have in
> there is too small, perhaps not a 270k at all.
>
> Ken
>
> >Sorry for the basic question, but which are the offset resistors? The
> >ones around the tl072 that outputs to the saw out?
> >
> >If so, I should mention I am using a 270k instead of the 240k, and a
> >560k instead of the 330k, which is what the elby instructions said to
> >do. I think everything else is per the schematics.
> >
> >
> >--- In cgs_synth@yahoogroups.com, sasami@ wrote:
> >>
> >> Usually caused by the signal hitting a power rail and running out of
> >> anywhere to go. It's what i'd expect to find if an offset resistor
> >was not
> >> soldered in propperly (or the wrong value), or some other voltage
> >> determining part. The name givven to this is "clipping".
> >>
> >> Ken
> >>
> >> >I got a working scope today, and the saw out of the VCO is very
> >> >strange. Rather than /|/|/|/| it goes -\-\-\-\. That is the
best I
> >> >can do, but the 1st example should be a normal saw, and the 2nd
> >> >example, whats going on is that it goes straight up, has a flat
top,
> >> >then slopes down. I tested my paia VCO and the shapes are fine,
so Im
> >> >sure Im using the scope correctly.
> >> >Any idea what could be causing this?
> >> >
> >> >Thanks,
> >> >Scott
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >The CGS Modular Synth home page: http://www.cgs.synth.net/
> >> >
> >> >Yahoo! Groups Links
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >>
_______________________________________________________________________
> >> Ken Stone sasami@ or sasami@
> >> Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
> >> Australian Miniature Horses & Ponies
<http://www.blaze.net.au/~sasami/>
> >>
> >
> >
> >
> >
> >
> >
> >
> >The CGS Modular Synth home page: http://www.cgs.synth.net/
> >
> >Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
> _______________________________________________________________________
> Ken Stone sasami@... or sasami@...
> Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
> Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>
>

On 3/8/06, c10h14no2i <c10h14no2i@...> wrote:
>
> I did check both resistors.. I even replaced them with what you have
> specified in the schemo's.
>
> When I test using the AC output from the VCO, I get +5/-15 volts.
> When I test w/ the DC output from the VCO the bottom of the wave
> starts at about +10 volts, and goes up to where I guess its clipping.
> I dont understand why there is such a difference between the ac and dc
> outputs. (does that give you any clues?)
>
> Then I dont understand why the square output is centered on 0, when it
> is getting its input from the saw, which is messed up.
>
> Also, I tested the output of the ca3140, and its a perfect saw
> centered on 0
>
> That sure narrows down where the trouble could be coming form.
> BUT, I have gone through, checked every component around the tl072,
> and heated each solder point to make sure its good. Still have the
> same problem. I know the circuit works, so Ive got to be missing
> something... I just can't find it!
> Is it possible that something is wrong w/ the tl074? Can an IC kind
> of work, or are they just good or bad? (unfortunately I built this
> module before I learned the value of ic sockets)
>
> Thanks again.
>
>
> --- In cgs_synth@yahoogroups.com, sasami@... wrote:
> >
> > The 240k is the offset resistor. it sounds like the resistor you have in
> > there is too small, perhaps not a 270k at all.
> >
> > Ken
> >
> > >Sorry for the basic question, but which are the offset resistors? The
> > >ones around the tl072 that outputs to the saw out?
> > >
> > >If so, I should mention I am using a 270k instead of the 240k, and a
> > >560k instead of the 330k, which is what the elby instructions said to
> > >do. I think everything else is per the schematics.
> > >
> > >
> > >--- In cgs_synth@yahoogroups.com, sasami@ wrote:
> > >>
> > >> Usually caused by the signal hitting a power rail and running out of
> > >> anywhere to go. It's what i'd expect to find if an offset resistor
> > >was not
> > >> soldered in propperly (or the wrong value), or some other voltage
> > >> determining part. The name givven to this is "clipping".
> > >>
> > >> Ken
> > >>
> > >> >I got a working scope today, and the saw out of the VCO is very
> > >> >strange. Rather than /|/|/|/| it goes -\-\-\-\. That is the
> best I
> > >> >can do, but the 1st example should be a normal saw, and the 2nd
> > >> >example, whats going on is that it goes straight up, has a flat
> top,
> > >> >then slopes down. I tested my paia VCO and the shapes are fine,
> so Im
> > >> >sure Im using the scope correctly.
> > >> >Any idea what could be causing this?
> > >> >
> > >> >Thanks,
> > >> >Scott
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >The CGS Modular Synth home page: http://www.cgs.synth.net/
> > >> >
> > >> >Yahoo! Groups Links
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >
> > >>
> _______________________________________________________________________
> > >> Ken Stone sasami@ or sasami@
> > >> Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/<http://www.blaze.net.au/%7Esasami/synth/>
> >
> > >> Australian Miniature Horses & Ponies
> <http://www.blaze.net.au/~sasami/ <http://www.blaze.net.au/%7Esasami/>>
> > >>
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >The CGS Modular Synth home page: http://www.cgs.synth.net/
> > >
> > >Yahoo! Groups Links
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > _______________________________________________________________________
> > Ken Stone sasami@... or sasami@...
> > Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/<http://www.blaze.net.au/%7Esasami/synth/>
> >
> > Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/<http://www.blaze.net.au/%7Esasami/>
> >
> >
>
>
>
>
>
>
> The CGS Modular Synth home page: http://www.cgs.synth.net/
>
>
>
>
> SPONSORED LINKS
> Sampler<http://groups.yahoo.com/gads?t=ms&k=Sampler&w1=Sampler&w2=Electronic+instrument&w3=Music+synthesizers&w4=Synthesizer+music&w5=Electronic+music&w6=Music+sampler&c=6&s=128&.sig=sxG9aCMlXQ2P1jigaHPKgA> Electronic
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> music<http://groups.yahoo.com/gads?t=ms&k=Synthesizer+music&w1=Sampler&w2=Electronic+instrument&w3=Music+synthesizers&w4=Synthesizer+music&w5=Electronic+music&w6=Music+sampler&c=6&s=128&.sig=PIjlwR8yB3UeCuv4rLd8wQ> Electronic
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> sampler<http://groups.yahoo.com/gads?t=ms&k=Music+sampler&w1=Sampler&w2=Electronic+instrument&w3=Music+synthesizers&w4=Synthesizer+music&w5=Electronic+music&w6=Music+sampler&c=6&s=128&.sig=_zm_bk9pqHBz8vqDp9fhdg>
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> ------------------------------
>


[Non-text portions of this message have been removed]

--- In cgs_synth@yahoogroups.com, "josh summitt" <ascetik@...> wrote:
>
> I've built two of these VCO's and on both of them i had to lower the
gain so
> that the SAW would not hit the voltage rails. I changed the 330k
resistor in
> the feedback loop of the tl072. Change it to a lower value. It
should not
> take much like maybe a 250k or something. I can't remember exactly
what i
> used.
> Josh
>
> On 3/8/06, c10h14no2i <c10h14no2i@...> wrote:
> >
> > I did check both resistors.. I even replaced them with what you have
> > specified in the schemo's.
> >
> > When I test using the AC output from the VCO, I get +5/-15 volts.
> > When I test w/ the DC output from the VCO the bottom of the wave
> > starts at about +10 volts, and goes up to where I guess its clipping.
> > I dont understand why there is such a difference between the ac and dc
> > outputs. (does that give you any clues?)
> >
> > Then I dont understand why the square output is centered on 0, when it
> > is getting its input from the saw, which is messed up.
> >
> > Also, I tested the output of the ca3140, and its a perfect saw
> > centered on 0
> >
> > That sure narrows down where the trouble could be coming form.
> > BUT, I have gone through, checked every component around the tl072,
> > and heated each solder point to make sure its good. Still have the
> > same problem. I know the circuit works, so Ive got to be missing
> > something... I just can't find it!
> > Is it possible that something is wrong w/ the tl074? Can an IC kind
> > of work, or are they just good or bad? (unfortunately I built this
> > module before I learned the value of ic sockets)
> >
> > Thanks again.
> >
> >
> > --- In cgs_synth@yahoogroups.com, sasami@ wrote:
> > >
> > > The 240k is the offset resistor. it sounds like the resistor you
have in
> > > there is too small, perhaps not a 270k at all.
> > >
> > > Ken
> > >
> > > >Sorry for the basic question, but which are the offset
resistors? The
> > > >ones around the tl072 that outputs to the saw out?
> > > >
> > > >If so, I should mention I am using a 270k instead of the 240k,
and a
> > > >560k instead of the 330k, which is what the elby instructions
said to
> > > >do. I think everything else is per the schematics.
> > > >
> > > >
> > > >--- In cgs_synth@yahoogroups.com, sasami@ wrote:
> > > >>
> > > >> Usually caused by the signal hitting a power rail and running
out of
> > > >> anywhere to go. It's what i'd expect to find if an offset
resistor
> > > >was not
> > > >> soldered in propperly (or the wrong value), or some other voltage
> > > >> determining part. The name givven to this is "clipping".
> > > >>
> > > >> Ken
> > > >>
> > > >> >I got a working scope today, and the saw out of the VCO is very
> > > >> >strange. Rather than /|/|/|/| it goes -\-\-\-\. That is the
> > best I
> > > >> >can do, but the 1st example should be a normal saw, and the 2nd
> > > >> >example, whats going on is that it goes straight up, has a flat
> > top,
> > > >> >then slopes down. I tested my paia VCO and the shapes are fine,
> > so Im
> > > >> >sure Im using the scope correctly.
> > > >> >Any idea what could be causing this?
> > > >> >
> > > >> >Thanks,
> > > >> >Scott
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >> >The CGS Modular Synth home page: http://www.cgs.synth.net/
> > > >> >
> > > >> >Yahoo! Groups Links
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >> >
> > > >>
> >
_______________________________________________________________________
> > > >> Ken Stone sasami@ or sasami@
> > > >> Modular Synth PCBs for sale
<http://www.blaze.net.au/~sasami/synth/<http://www.blaze.net.au/%7Esasami/synth/>
> > >
> > > >> Australian Miniature Horses & Ponies
> > <http://www.blaze.net.au/~sasami/
<http://www.blaze.net.au/%7Esasami/>>
> > > >>
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >The CGS Modular Synth home page: http://www.cgs.synth.net/
> > > >
> > > >Yahoo! Groups Links
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > >
_______________________________________________________________________
> > > Ken Stone sasami@ or sasami@
> > > Modular Synth PCBs for sale
<http://www.blaze.net.au/~sasami/synth/<http://www.blaze.net.au/%7Esasami/synth/>
> > >
> > > Australian Miniature Horses & Ponies
<http://www.blaze.net.au/~sasami/<http://www.blaze.net.au/%7Esasami/>
> > >
> > >
> >
> >
> >
> >
> >
> >
> > The CGS Modular Synth home page: http://www.cgs.synth.net/
> >
> >
> >
> >
> > SPONSORED LINKS
> >
Sampler<http://groups.yahoo.com/gads?t=ms&k=Sampler&w1=Sampler&w2=Electronic+instrument&w3=Music+synthesizers&w4=Synthesizer+music&w5=Electronic+music&w6=Music+sampler&c=6&s=128&.sig=sxG9aCMlXQ2P1jigaHPKgA>
Electronic
> >
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Music
> >
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Synthesizer
> >
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Electronic
> >
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Music
> >
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> > ------------------------------
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>
> [Non-text portions of this message have been removed]
>