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It's finished...I think.

It's finished...I think.

2004-10-31 by stuadh

I've just completed my first GCS module, hurray. I'm not sure if it
works, though. It is the simple wavefolder. Thing is, should
there be large parts of the range that are silent. When you turn
the Pot to give the lowest resistance to the incoming signal,
there is some output, but for most of the travel, there is nothing.
The SAW out is also particularly quiet. Is this normal? I've
replaced the TL072, both transistors, the pot and I've checked all
the resistors are correct. Any ideas

Yours Aye

Stuadh

Re: It's finished...I think.

2004-10-31 by sasami@hotkey.net.au

Something is amiss. First, try putting a 100n capacitor in series with the
input. This will get rid of any DC offset that may be upsetting it.

If that fails, report back :)

Ken
Show quoted textHide quoted text
>
>
>I've just completed my first GCS module, hurray. I'm not sure if it
>works, though. It is the simple wavefolder. Thing is, should
>there be large parts of the range that are silent. When you turn
>the Pot to give the lowest resistance to the incoming signal,
>there is some output, but for most of the travel, there is nothing.
>The SAW out is also particularly quiet. Is this normal? I've
>replaced the TL072, both transistors, the pot and I've checked all
>the resistors are correct. Any ideas
>
>Yours Aye
>
>Stuadh
>
>
>
>
>
>
>See the following URLS for the CGS Modular Synth home page:
>Main: http://www.cgs.synth.net/
>Secondary: http://otherunicorn.0catch.com/synth/
>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/>

Re: It's finished...I think.

2004-10-31 by stuadh

No discernible change.

(Very prompt again, thanks)

Stuadh
Show quoted textHide quoted text
--- In cgs_synth@yahoogroups.com, sasami@h... wrote:
> Something is amiss. First, try putting a 100n capacitor in
series with the
> input. This will get rid of any DC offset that may be upsetting it.
>
> If that fails, report back :)
>
> Ken
>
>
> >
> >
> >I've just completed my first GCS module, hurray. I'm not sure
if it
> >works, though. It is the simple wavefolder. Thing is, should
> >there be large parts of the range that are silent. When you
turn
> >the Pot to give the lowest resistance to the incoming signal,
> >there is some output, but for most of the travel, there is
nothing.
> >The SAW out is also particularly quiet. Is this normal? I've
> >replaced the TL072, both transistors, the pot and I've checked
all
> >the resistors are correct. Any ideas
> >
> >Yours Aye
> >
> >Stuadh
> >
> >
> >
> >
> >
> >
> >See the following URLS for the CGS Modular Synth home
page:
> >Main: http://www.cgs.synth.net/
> >Secondary: http://otherunicorn.0catch.com/synth/
> >Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
> >
>
__________________________________________________
_____________________
> Ken Stone sasami@h... or sasami@c...
> Modular Synth PCBs for sale
<http://www.blaze.net.au/~sasami/synth/>
> Australian Miniature Horses & Ponies
<http://www.blaze.net.au/~sasami/>

Re: It's finished...I think.

2004-10-31 by sasami@hotkey.net.au

Hmmm...

There are likely to be two problem areas-
1) construction
2) interface.

1) you seem think you have this sorted. In fact, it is very unlikely that
any components were damaged at any stage, short of doing something
catastrophic like reversing the power supply. There may however still be
construction errors. For example, if an alternate type of transistor was
used, the collector and emitter connections may be the other way around to
what is shown on the PCB.

2) The SAW output is the main output. If it is excessively quite, either
there is either
2a) a construction problem (see reversed transistors) or
2b) an inadequate signal being fed into the device. This wants a sawtooth
wave that is in the area of 5 to 10 volts in hight, before attenuation (via
the pot). It seems to me that you may be feeding it a signal that is simply
too weak. In that case, see the gain stage of the stomp-box adapter to boost
your signal level. (or another suitable pre-amp)

Ken
Show quoted textHide quoted text
>
>No discernible change.
>
>(Very prompt again, thanks)
>
>Stuadh
>
>--- In cgs_synth@yahoogroups.com, sasami@h... wrote:
>> Something is amiss. First, try putting a 100n capacitor in
>series with the
>> input. This will get rid of any DC offset that may be upsetting it.
>>
>> If that fails, report back :)
>>
>> Ken
>>
>>
>> >
>> >
>> >I've just completed my first GCS module, hurray. I'm not sure
>if it
>> >works, though. It is the simple wavefolder. Thing is, should
>> >there be large parts of the range that are silent. When you
>turn
>> >the Pot to give the lowest resistance to the incoming signal,
>> >there is some output, but for most of the travel, there is
>nothing.
>> >The SAW out is also particularly quiet. Is this normal? I've
>> >replaced the TL072, both transistors, the pot and I've checked
>all
>> >the resistors are correct. Any ideas
>> >
>> >Yours Aye
>> >
>> >Stuadh
>> >
>> >
>> >
>> >
>> >
>> >
>> >See the following URLS for the CGS Modular Synth home
>page:
>> >Main: http://www.cgs.synth.net/
>> >Secondary: http://otherunicorn.0catch.com/synth/
>> >Yahoo! Groups Links
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>>
>__________________________________________________
>_____________________
>> Ken Stone sasami@h... or sasami@c...
>> Modular Synth PCBs for sale
><http://www.blaze.net.au/~sasami/synth/>
>> Australian Miniature Horses & Ponies
><http://www.blaze.net.au/~sasami/>
>
>
>
>
>
>
>See the following URLS for the CGS Modular Synth home page:
>Main: http://www.cgs.synth.net/
>Secondary: http://otherunicorn.0catch.com/synth/
>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/>

Re: It's finished...I think.

2004-10-31 by stuadh

Hooray!

This was a definite case of RTFQ...Read The F***ing Question.
I had put in 2 x 2N3906 transistors, rather than a 2N3904. I've
replaced one with an alternative (BC547) and things are much
better. The signal still tails out as I turn the pot down, but
checking the outputs from the Analogue Systems VCO, they are
borderline to run the module anyway...(PLS - ±5V, SAW +8/-2V).
Nevermind, I just bought a Doepfer Pre-amp module off of eBay
so I'll check it out with that when it arrives.

Many thanks, and I can get on with builbing the VCO.

Stuadh
Show quoted textHide quoted text
--- In cgs_synth@yahoogroups.com, sasami@h... wrote:
> Hmmm...
>
> There are likely to be two problem areas-
> 1) construction
> 2) interface.
>
> 1) you seem think you have this sorted. In fact, it is very unlikely
that
> any components were damaged at any stage, short of doing
something
> catastrophic like reversing the power supply. There may
however still be
> construction errors. For example, if an alternate type of
transistor was
> used, the collector and emitter connections may be the other
way around to
> what is shown on the PCB.
>
> 2) The SAW output is the main output. If it is excessively quite,
either
> there is either
> 2a) a construction problem (see reversed transistors) or
> 2b) an inadequate signal being fed into the device. This wants
a sawtooth
> wave that is in the area of 5 to 10 volts in hight, before
attenuation (via
> the pot). It seems to me that you may be feeding it a signal that
is simply
> too weak. In that case, see the gain stage of the stomp-box
adapter to boost
> your signal level. (or another suitable pre-amp)
>
> Ken
>
>
>
> >
> >No discernible change.
> >
> >(Very prompt again, thanks)
> >
> >Stuadh
> >
> >--- In cgs_synth@yahoogroups.com, sasami@h... wrote:
> >> Something is amiss. First, try putting a 100n capacitor in
> >series with the
> >> input. This will get rid of any DC offset that may be upsetting
it.
> >>
> >> If that fails, report back :)
> >>
> >> Ken
> >>
> >>
> >> >
> >> >
> >> >I've just completed my first GCS module, hurray. I'm not
sure
> >if it
> >> >works, though. It is the simple wavefolder. Thing is,
should
> >> >there be large parts of the range that are silent. When you
> >turn
> >> >the Pot to give the lowest resistance to the incoming
signal,
> >> >there is some output, but for most of the travel, there is
> >nothing.
> >> >The SAW out is also particularly quiet. Is this normal? I've
> >> >replaced the TL072, both transistors, the pot and I've
checked
> >all
> >> >the resistors are correct. Any ideas
> >> >
> >> >Yours Aye
> >> >
> >> >Stuadh
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >See the following URLS for the CGS Modular Synth home
> >page:
> >> >Main: http://www.cgs.synth.net/
> >> >Secondary: http://otherunicorn.0catch.com/synth/
> >> >Yahoo! Groups Links
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
> >>
>
>_________________________________________________
_
> >_____________________
> >> Ken Stone sasami@h... or sasami@c...
> >> Modular Synth PCBs for sale
> ><http://www.blaze.net.au/~sasami/synth/>
> >> Australian Miniature Horses & Ponies
> ><http://www.blaze.net.au/~sasami/>
> >
> >
> >
> >
> >
> >
> >See the following URLS for the CGS Modular Synth home
page:
> >Main: http://www.cgs.synth.net/
> >Secondary: http://otherunicorn.0catch.com/synth/
> >Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> >
> >
>
__________________________________________________
_____________________
> Ken Stone sasami@h... or sasami@c...
> Modular Synth PCBs for sale
<http://www.blaze.net.au/~sasami/synth/>
> Australian Miniature Horses & Ponies
<http://www.blaze.net.au/~sasami/>

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