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L´Andratté
Joined: Sep 23, 2012 Posts: 150 Location: Hamburg, Germany
Audio files: 5
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Posted: Sun Dec 08, 2013 5:44 pm Post subject:
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Hello Beep!
Just to make sure: you are aware that a dual supply can easily be generated with 2 batteries?
+9V/-9V should work with most +12/-12 circuits also(probably minor changes...).
Otoh maybe you just wanna do it your way! |
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beep
Joined: May 05, 2013 Posts: 105 Location: Germany
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Posted: Mon Jan 06, 2014 11:55 am Post subject:
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Hey L´Andratté
I know the two battery dual supply solution, but my
intention was to design an easy to build synth, which
will run from battery as well as from a DC wall wart,
like the SH101.
back to topic:
I soldered the latest schematic by René on stripboard
without breadboarding before. I used an op amp like
in the single op amp saw vco. but with a 2.2nF poly cap
instead of the 100nF from Metal_head's design.
It works, but its pitch is much to high even if CV is 0V
should I use a 100nF cap?
edit: Tried a 100nF cap now, got lower pitch but at higher pitches
the oscillator stops oscillating somehow. I can re-activate it
by touching some random pins on the stripboard _________________ Is the future obsolete? Last edited by beep on Tue Jan 07, 2014 1:25 am; edited 1 time in total |
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beep
Joined: May 05, 2013 Posts: 105 Location: Germany
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Posted: Tue Jan 07, 2014 1:17 am Post subject:
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...aaand collector AND base of Q4 are connected to the base
of Q5, is this right? _________________ Is the future obsolete? |
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beep
Joined: May 05, 2013 Posts: 105 Location: Germany
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Posted: Wed Jan 08, 2014 7:21 am Post subject:
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I made a voltage divider with a trimmer at the power supply to connect R4 to a lower voltage than 12V. Now I can adjust the initial pitch of the VCO,
then connected a squarewave LFO to another CV input and adjusted its
modulation intensity to get a musical interval (5ths) then I swept through
the available audio range (~4 ovtaves) and it worked great. at the higher pitches, the modulation range is still fucked up, but it works very well already. I want to take further research on this to improve the tracking.
I also have to figure out, where to place the NTCs. The vco is very temperature sensitive. _________________ Is the future obsolete? |
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beep
Joined: May 05, 2013 Posts: 105 Location: Germany
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rene_schmitz
Joined: Oct 27, 2013 Posts: 16 Location: germany
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Posted: Thu Jan 09, 2014 5:22 am Post subject:
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Hi Beep,
nice to see that you're also working on it.
I've breadboarded it, and I noticed too that the range is set too high. I was using only 5V supply.
However if you change the cap, you'll have to adapt/adjust the HFT as well.
Another option is to make the R4 resistor bigger than 1M to shift things down. I think best is to use both approaches. Maybe 22n and 4M7 or so.
Oh, and you're right about the base and collector of Q4 being tied together.
Cheers,
René _________________ My site: http://www.schmitzbits.de |
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beep
Joined: May 05, 2013 Posts: 105 Location: Germany
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Posted: Thu Jan 09, 2014 1:17 pm Post subject:
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And how happy I am that you're also working on it
I added a 47nF capacitor without changing any resistors
and I got nice low pitch at lowest cv. but when I increased the
cv, the vco suddenly stopped to oscillate. I had a 2n2 poly cap
in parallel with the additional 47n ceramic cap.
is the HFT the reset time compensation trimmer?
It slightly changes the pitch. But this is not the
replacement of the v/oct trimmer, is it?
can I just add the 10k NTCs and the 1k v/oct trimmer
as in the vco4069?
The simulator told me that I can get lower pitches when I apply negative
CV, but there is no source for negative CV, so lowest CV must be 0V
ROCK'N'ROLL! _________________ Is the future obsolete? |
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MickeyDelp
Joined: Feb 26, 2010 Posts: 42 Location: Austin TX
Audio files: 1
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Posted: Mon Feb 10, 2014 5:37 pm Post subject:
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I breadboarded this circuit today. Given that breadboards introduce lots of parasitic capacitance and power supply noise and switching noise, etc. The 40106 oscillator is horribly noisy and unstable. The waveform was jiggling all over the scope. It also made it impossible to use any of the other Schmitt triggers in the 40106. The op amp version, however, sounds beautiful! _________________ MickeyDelp.com
Delptronics.com |
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beep
Joined: May 05, 2013 Posts: 105 Location: Germany
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Posted: Tue Feb 11, 2014 8:46 am Post subject:
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Heyy, did you have success getting it working with 1V/oct properly? _________________ Is the future obsolete? |
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MickeyDelp
Joined: Feb 26, 2010 Posts: 42 Location: Austin TX
Audio files: 1
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Posted: Tue Feb 11, 2014 2:26 pm Post subject:
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beep wrote: | Heyy, did you have success getting it working with 1V/oct properly? |
I did not try. It is not necessary for my application (drone synth).
I hope that you and René continue to work on it though. The world needs a good single supply exponential converter. _________________ MickeyDelp.com
Delptronics.com |
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JingleJoe
Joined: Nov 10, 2011 Posts: 878 Location: Lancashire, England
Audio files: 14
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Posted: Thu Feb 13, 2014 8:11 am Post subject:
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MickeyDelp wrote: | I breadboarded this circuit today. Given that breadboards introduce lots of parasitic capacitance and power supply noise and switching noise, etc. The 40106 oscillator is horribly noisy and unstable. The waveform was jiggling all over the scope. It also made it impossible to use any of the other Schmitt triggers in the 40106. The op amp version, however, sounds beautiful! |
did you tie the unused 40106 inputs to GND? and use a power supply filter cap? missing either of those can cause the problems you had.
by the way I tried the expo converter posted by Rene but in a different circuit, I couldn't get it to work... i also don't fully understand just what's going on there (with the expo) I thought I did but I think not now because of my lack of ability to make it work _________________ As a mad scientist I am ruled by the dictum of science: "I could be wrong about this but lets find out"
Green Dungeon Alchemist Laboratories |
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MickeyDelp
Joined: Feb 26, 2010 Posts: 42 Location: Austin TX
Audio files: 1
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Posted: Thu Feb 13, 2014 8:24 am Post subject:
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JingleJoe wrote: | did you tie the unused 40106 inputs to GND? and use a power supply filter cap? missing either of those can cause the problems you had. |
Yes, and yes. Tying the unused inputs to ground did stabilize the waveform a bit, but the other inverters in the 40106 are still unusable. Basically, it is using a 16 pin chip where an 8 pin op amp works better. _________________ MickeyDelp.com
Delptronics.com |
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JingleJoe
Joined: Nov 10, 2011 Posts: 878 Location: Lancashire, England
Audio files: 14
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Posted: Thu Feb 13, 2014 8:35 am Post subject:
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MickeyDelp wrote: | JingleJoe wrote: | did you tie the unused 40106 inputs to GND? and use a power supply filter cap? missing either of those can cause the problems you had. |
Yes, and yes. Tying the unused inputs to ground did stabilize the waveform a bit, but the other inverters in the 40106 are still unusable. Basically, it is using a 16 pin chip where an 8 pin op amp works better. |
I agree entirely, it is a bit of a waste of most of an IC, however if it gets the job done and doesn't break the bank or cause mass destruction, then by my standards that's okay for some kind of ramshacke hacker like me
oh also I wanted to add, I made a single supply expo converter, it's not the best but it gets the job done for what I wanted: exponentiation for the CV applied to a VCF or VCA. Tuning is a bit fiddly but it can be made to work with a VCO... I thought I posted it here? I'm sure I made a thread about it, have a search _________________ As a mad scientist I am ruled by the dictum of science: "I could be wrong about this but lets find out"
Green Dungeon Alchemist Laboratories |
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beep
Joined: May 05, 2013 Posts: 105 Location: Germany
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Posted: Tue Jun 16, 2015 4:06 pm Post subject:
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He's my hero. it works. I'm playing on a dual VCO powered by a 9V battery at the moment. controlled by the CV out of my arturia microbrute, which is 1v/oct.
http://electro-music.com/forum/post-409907.html#409907 _________________ Is the future obsolete? |
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Shock_Hazard
Joined: Jul 17, 2015 Posts: 16 Location: Gwynedd
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Posted: Tue Jul 21, 2015 11:08 am Post subject:
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so how did you get this working? I made a post in that thread, I'm having some trouble :/ |
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