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Thread
2007-06-06 by Jorrit Tyberghein
2007-06-06 by James Dunn
>
> Hi all,
>
> Why exactly does the CGS64 (VCA) require matched transistors? What
> happens if you just use random transistors? In what way will the VCA
> not work correctly then?
>
> Greetings and thanks,
>
>
2007-06-06 by sasami@hotkey.net.au
>Hi all,_______________________________________________________________________
>
>Why exactly does the CGS64 (VCA) require matched transistors? What
>happens if you just use random transistors? In what way will the VCA
>not work correctly then?
>
>Greetings and thanks,
>
>
>
>The CGS Modular Synth home page: http://www.cgs.synth.net/
>
>Yahoo! Groups Links
>
>
>
>
2007-06-07 by Dave Kendall
On 7 Jun 2007, at 00:52, sasami@... wrote:
> They are matched to null out the signal. Unmatched transistors may have
> audio bleedthrough. There is no reason why you can't try a pair of
> ordinary
> transistors, though your success will be greater if you can get a
> pair from
> the same batch.
>
Would matching with the transistor tester in a DMM do the trick, or do
you need to measure parameters other than HFE?
cheers,
Dave
[Non-text portions of this message have been removed]
2007-06-07 by Louis van Dompselaar
> Would matching with the transistor tester in a DMM do the trick, or doTransistors are usually matched on Vbe.
> you need to measure parameters other than HFE?
2007-06-07 by Dave Kendall
On 7 Jun 2007, at 11:58, Louis van Dompselaar wrote:
>
> > Would matching with the transistor tester in a DMM do the trick, or
> do
> > you need to measure parameters other than HFE?
>
> Transistors are usually matched on Vbe.
>
> That said, transistors /from the same batch/ that are close in Hfe are
> probably
> close in other specs as well. So yes, you might get away with
> checking Hfe.
>
> I did just that building the Yusynth Minimoog clone and it sounds
> great and
> even tracks well enough. That might also be plain good fortune though
> ;)
>
> Check this thread:
> http://electro-music.com/forum/viewtopic.php?highlight=matching&t=18365
>
> Louis
>
Thanks for the tip.
I checked this circuit
http://www.oldcrows.net/~patchell/matcher/matcher.html
It shows a PNP tranny.
Would NPNs also work?
Also (this may be a dumb question....) What does the D.U.T. refer to at
top right of the schemo? GND maybe? it isn't the
multimeter............
cheers,
Dave
[Non-text portions of this message have been removed]
2007-06-07 by sasami@hotkey.net.au
>Thanks for the tip.Reverse all polarities for NPNs (i.e. the power supply, any diodes, and
>I checked this circuit
>http://www.oldcrows.net/~patchell/matcher/matcher.html
>It shows a PNP tranny.
>Would NPNs also work?
>Also (this may be a dumb question....) What does the D.U.T. refer to atD.U.T. = Device Under Test, namely the transistor you are testing.
>top right of the schemo? GND maybe? it isn't the
>multimeter............
2007-06-08 by Dave Kendall
On 7 Jun 2007, at 14:43, sasami@... wrote:
>
> >Thanks for the tip.
> >I checked this circuit
> >http://www.oldcrows.net/~patchell/matcher/matcher.html
> >It shows a PNP tranny.
> >Would NPNs also work?
>
> Reverse all polarities for NPNs (i.e. the power supply, any diodes,
> and
> electros etc).
>
> >Also (this may be a dumb question....) What does the D.U.T. refer to
> at
> >top right of the schemo? GND maybe? it isn't the
> >multimeter............
>
> D.U.T. = Device Under Test, namely the transistor you are testing.
>
> Ken
> __________________________________________________________
> Ken Stone sasami@...
> Modular Synth PCBs for sale <http://www.cgs.synth.net/>
> Australian Miniature Horses & Ponies
> <http://www.blaze.net.au/~sasami/>
>
>
>
>
[Non-text portions of this message have been removed]
2007-06-08 by Larry T.
--- In cgs_synth@yahoogroups.com, Dave Kendall <davekendall@...> wrote:
>
> Thanks guys.
>
> :-)
>
> On 7 Jun 2007, at 14:43, sasami@... wrote:
>
> >
> > >Thanks for the tip.
> > >I checked this circuit
> > >http://www.oldcrows.net/~patchell/matcher/matcher.html
> > >It shows a PNP tranny.
> > >Would NPNs also work?
> >
> > Reverse all polarities for NPNs (i.e. the power supply, any diodes,
> > and
> > electros etc).
> >
> > >Also (this may be a dumb question....) What does the D.U.T.
refer to
> > at
> > >top right of the schemo? GND maybe? it isn't the
> > >multimeter............
> >
> > D.U.T. = Device Under Test, namely the transistor you are testing.
> >
> > Ken
2007-06-08 by Louis van Dompselaar
> continuing in the 'dumb' question category, Jim's diagram only shown
> on connection for the Device Under Test. Could someone 'fill in the
> blanks' as to how the dut is actually connected?
2007-06-08 by Dave Kendall
On 8 Jun 2007, at 16:08, Louis van Dompselaar wrote:
> The "D.U.T." is in a confusing place. It is meant to indicate
> the transistor in the diagram. The arrow that it is next to is just
> the ground connection.
>
> > continuing in the 'dumb' question category, Jim's diagram only shown
> > on connection for the Device Under Test. Could someone 'fill in the
> > blanks' as to how the dut is actually connected?
>
>
>
>
[Non-text portions of this message have been removed]
2007-06-08 by Larry T.
--- In cgs_synth@yahoogroups.com, Dave Kendall <davekendall@...> wrote:
>
> Larry asked the question I didn't dare, lest I got categorized as being
> in permanent blonde mode....
> Relieved to see it wasn't only me that wondered....
>
> Seeing as the bottle of peroxide is on the table now, does anyone else
> find the use of a downward pointing arrow for GND instead of -V as
> confusing as I do when it sometimes turns up in a schemo?
> Is there a good reason for it?
>
> "Standards are marvellous, That's why we have so many of them......."
>
> :-)
>
> Dave
>
>
>
> On 8 Jun 2007, at 16:08, Louis van Dompselaar wrote:
>
> > The "D.U.T." is in a confusing place. It is meant to indicate
> > the transistor in the diagram. The arrow that it is next to is just
> > the ground connection.
> >
2007-06-08 by Louis van Dompselaar
> the use of a downward pointing arrow for GND instead of -V
2007-06-08 by Dave Kendall
> That can't be "instead of". Those are two completely differentThat's what I mean - I've seen some schematics where the down arrow
> things...
On 8 Jun 2007, at 18:55, Larry T. wrote:
> okay then. I'm not that used to +/- supply layouts. I remember the
> following 'text' diagram as ground:
>
> |
> |
> -----
> ---
> -
Me too....it seems much more common.....
cheers,
Dave
[Non-text portions of this message have been removed]
2007-06-08 by Ehud Tamir
On 8 Jun 2007, at 19:16, Louis van Dompselaar wrote:
> That can't be "instead of". Those are two completely different
> things...
That's what I mean - I've seen some schematics where the down arrow
indicates a connection to GND. Most schemos I've come across show a
down arrow connecting to neg voltage.
there are some schemos on GEOFEX that use a down arrow for GND for
example.
They're indeed not the same, I just wondered why the 2 different ways
of showing a ground connection.
On 8 Jun 2007, at 18:55, Larry T. wrote:
> okay then. I'm not that used to +/- supply layouts. I remember the
> following 'text' diagram as ground:
>
> |
> |
> -----
> ---
> -
Me too....it seems much more common.....
cheers,
Dave
[Non-text portions of this message have been removed]
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[Non-text portions of this message have been removed]
2007-06-19 by bill bigrig
>http://electro-music.com/forum/viewtopic.php?highlight=matching&t=18365
> > Would matching with the transistor tester in a DMM
> do the trick, or do
> > you need to measure parameters other than HFE?
>
> Transistors are usually matched on Vbe.
>
> That said, transistors /from the same batch/ that
> are close in Hfe are
> probably
> close in other specs as well. So yes, you might get
> away with checking Hfe.
>
> I did just that building the Yusynth Minimoog clone
> and it sounds great and
> even tracks well enough. That might also be plain
> good fortune though ;)
>
> Check this thread:
>
>____________________________________________________________________________________Ready for the edge of your seat?
> Louis
>
>
>
> [Non-text portions of this message have been
> removed]
>
>
2007-06-19 by Pete
On 6/18/07, bill bigrig <billbigrig@...> wrote:
>
> Howdy,
>
> This is going to sound stupid, but after trying
> tosize transistors for a project, I have NO idea what
> HFE or Vbe is. Could you give me a brief explanation/
> Thanx
> Rig
>
> -
>
--
http://www.myspace.com/23isgood
[Non-text portions of this message have been removed]
2007-06-19 by sasami@hotkey.net.au
> That's a very good question. I would like to know too. This is a great_______________________________________________________________________
>thread. Lots of good info.
>
>thanks folks
>pete
>
>On 6/18/07, bill bigrig <billbigrig@...> wrote:
>>
>> Howdy,
>>
>> This is going to sound stupid, but after trying
>> tosize transistors for a project, I have NO idea what
>> HFE or Vbe is. Could you give me a brief explanation/
>> Thanx
>> Rig
>>
>> -
>>
>
>
>--
>http://www.myspace.com/23isgood
>
>
>[Non-text portions of this message have been removed]
>
>
>
>The CGS Modular Synth home page: http://www.cgs.synth.net/
>
>Yahoo! Groups Links
>
>
>
>