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funkyfarm
Joined: Jan 21, 2007
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funkyfarm
Joined: Jan 21, 2007
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 Posted: Fri Apr 27, 2007 9:59 am Post subject:
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Here is the core circuit and editor's note.
The trick is to bypass C3 cap with a CMOS switch...
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funkyfarm
Joined: Jan 21, 2007
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sneakthief
Joined: Jul 24, 2006
Posts: 569
Location: Berlin
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| Posted: Sat Apr 28, 2007 12:55 pm Post subject:
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Maybe Mr. Henry would like to chime in here? It really sounds quite nice and looks simple to build!
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Sneak-Thief - raw electrofunk |
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Scott Stites
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Posts: 4127
Location: Mount Hope, KS USA
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| Posted: Sun Apr 29, 2007 12:55 am Post subject:
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I built a module for Jeff Pontius that had Thomas' quadrature function generator in it and Rene Schmitz's tri-phase VCLFO. Here's a pic of it when I built it, and a pic Jeff took later after he had a Schaeffer panel made for it.
Thomas' QFG is also included in my long-neglected MultiPhase project....
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| After Jeff put the Schaeffer panel on it. |
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| The module after I built it. |
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funkyfarm
Joined: Jan 21, 2007
Posts: 583
Location: France
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| Posted: Sun Apr 29, 2007 11:31 am Post subject:
FRYING ICs... |
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Yep !
my 3P LFO is waiting for one 4052 
As I have three "CD4016 CMOS Quad Bilateral Switch" as spare (?!), i will give a try with this IC for the modification...bzzz... |
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funkyfarm
Joined: Jan 21, 2007
Posts: 583
Location: France
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| Posted: Mon Apr 30, 2007 2:58 am Post subject:
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I've tried with a 4016...something like this...
Whenever SYNC gate s high or low, it freezes LFO oscillation...
Even with a good switching solution, maybe the incoming SYNC signal should be "trigged" (small RC network or cap in series) ; as in the CGS Gate to Trigger Converter
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v-un-v
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Posted: Mon Apr 30, 2007 4:25 pm Post subject:
Re: TH’s Quadrature Function Generator sync mod
Subject description: Thomas Henry’s QFG mod according to POLYPHONY 1984 |
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| funkyfarm wrote: | I’ve build the QFG.
Here is the test... |
that's a test??? 
It's beautiful! 
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ALLES TURISTEN UND NONTEKNISCHEN LOOKENPEEPERS!
DAS KOMPUTERMASCHINE IST NICHT FÜR DER GEFINGERPOKEN UND MITTENGRABEN! ODERWISE IST EASY TO SCHNAPPEN DER SPRINGENWERK, BLOWENFUSEN UND POPPENCORKEN MIT SPITZENSPARKSEN.
IST NICHT FÜR GEWERKEN BEI DUMMKOPFEN. DER RUBBERNECKEN SIGHTSEEREN KEEPEN DAS COTTONPICKEN HÄNDER IN DAS POCKETS MUSS.
ZO RELAXEN UND WATSCHEN DER BLINKENLICHTEN. |
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mosc
Site Admin
Joined: Jan 31, 2003
Posts: 18138
Location: Durham, NC
Audio files: 192
G2 patch files: 60
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| Posted: Mon Apr 30, 2007 5:56 pm Post subject:
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It IS beautiful. How about some real music.
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--Howard
my music and other stuff |
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Scott Stites
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Joined: Dec 23, 2005
Posts: 4127
Location: Mount Hope, KS USA
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| Posted: Mon Apr 30, 2007 6:52 pm Post subject:
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| Doh! I downloaded the sample on dial-up then realized I'm sort of in Uncle K's shoes - I moved my speakers downstairs. |
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Scott Stites
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Joined: Dec 23, 2005
Posts: 4127
Location: Mount Hope, KS USA
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| Posted: Tue May 01, 2007 10:59 am Post subject:
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OK, I heard it. Tom was right - that's beautiful!
Do you have any details on the patch?
Were Vactrols involved?
Cheers,
Scott |
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RF
Joined: Mar 23, 2007
Posts: 1502
Location: Northern Minnesota, USA
Audio files: 28
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| Posted: Wed May 02, 2007 4:26 am Post subject:
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That's a very cool sound sample! I'm also interested in what the patch consisted of...
Thanks for the link to the article, too. This one goes on my list of things to do. |
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fonik
Joined: Jun 07, 2006
Posts: 3950
Location: Germany
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| Posted: Thu May 03, 2007 1:03 am Post subject:
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| funkyfarm wrote: | | I've tried with a 4016...Whenever SYNC gate s high or low, it freezes LFO oscillation... |
so it didn't work? what could be the cause? didn't the switch refuse to switch?
and what a nice sample! i suddenly reminded my old pocket calculator 
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matthias
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funkyfarm
Joined: Jan 21, 2007
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funkyfarm
Joined: Jan 21, 2007
Posts: 583
Location: France
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| Posted: Thu May 10, 2007 4:06 am Post subject:
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about the sync mod, I have to admit that when I test firing the ENABLE input of the IC (which was ok), I've read strange "switching" values on my ohmmeter for what we're dealing with...
Guess I have to check the specs of the 4000 switches (and all the boring stuff...)
I have a 4066...will give a try...re-bzzz...
PS : Scoop about the sample : main sequence is from a SH-101 but I've swapped my real-shit-computer-based midi beat clock (1/32 as master clock) with Art Blakey's real funky riding groove
SWING is the key |
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fluxmonkey
Joined: Jun 24, 2005
Posts: 708
Location: cleve
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| Posted: Thu May 10, 2007 7:03 pm Post subject:
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is anyone thinking about doing a PCB or stripboard layout for this one? quadrature function generators being one of the harder-to find modules (along w/ quantizers), diy or assembled... sure would be nice...
b |
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Adam-V
Joined: Jan 29, 2007
Posts: 300
Location: Australia
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| Posted: Thu May 10, 2007 9:14 pm Post subject:
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Doepfer have got a VC Quadrature LFO planned for release in July.
Cheers,
Adam-V |
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funkyfarm
Joined: Jan 21, 2007
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Location: France
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| Posted: Fri May 11, 2007 9:58 am Post subject:
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| Adam-V wrote: | Doepfer have got a VC Quadrature LFO planned for release in July.
Cheers,
Adam-V |
Yep ! but surely with sine waveforms...
maybe the same as Jim Patchell’s VC Quadrature Oscillator ? |
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Scott Stites
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| Posted: Fri May 11, 2007 10:18 am Post subject:
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If it's sine waves you want, getcherself a Mankato filter - that baby's got quadrature out the ying-yang. Plus it's a filter, pocket fisherman, and makes wonderful julienne fries.
Looks like they're right around the corner.
Cheers,
Scott |
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funkyfarm
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Scott Stites
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| Posted: Fri May 11, 2007 11:10 am Post subject:
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Yep - Thomas is great at manipulating a circuit to do what he wants. He's not violating any rules either - even though Vcc is connected to 0V (ground) he's still powering the IC from +15V, in relation to what he's got attached to the ground connection, which is -15V. He does that a lot
I think Thomas would be the first to tell you he didn't invent this technique (it's more or less the same kind of thing as using Vcc/2 as the reference for processing audio with a single supply op amp, which nearly every stompbox in the world has to do), but I think it's a powerful part of his approach for wringing the most functionality out of an IC or a circuit. Where I look at a chip's specs and see "it requires X number of volts supply", I never think of it in terms of "X volts in reference to what?". Thomas does.
Cheers,
Scott |
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RF
Joined: Mar 23, 2007
Posts: 1502
Location: Northern Minnesota, USA
Audio files: 28
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| Posted: Mon May 14, 2007 6:23 pm Post subject:
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Question for the brain trust here....
I built the QFG over the weekend - but...... Not having a 1458 in the parts bin I stuck in an LM358.
So the 'derived' output is indeed 90 degrees out of phase...but a bit jumpy  . I played with the value of C1 and juggled a couple resistors to make it usable, but it's still a bit rough. Is this the issue Mr. Henry is refering to in the article re: the slow slew rate in the 1458 masking discontinuities?
Ooops. I just looked at the schematic again and realized I'm running it off +- 12 volts rather than the 15 specified. ummm....? Seems to work except for the derived being a bit rough...
Input?
Mr. Henry - Hi from 'up north'. I recall vividly (and with some trepidation) a few college days road trips to 'Kato. |
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Tim Servo
Joined: Jul 16, 2006
Posts: 924
Location: Silicon Valley
Audio files: 11
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| Posted: Tue May 15, 2007 8:51 am Post subject:
TH’s Quadrature Function Generator sync mod |
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| funkyfarm wrote: | I don't know if it's the trick to get this cool quadrature triangle waveforms, but "NOTE UNUSUAL POWER SUPPLY CONNECTION TO IC3"
Whaouhhhhhhhhhhhhhhhhh !
I guess this IS the real luxe, being able to choose some "unusual power supply connections" to an IC
Or, maybe, first result was convaincing, but with a positive 15 volts offset ? |
Hey Funky,
What the "unusual" power supply gets you is a signal that is conditioned correctly for the next stage in the circuit. In Thomas' original QFG design, an additional op amp inverter is used after the "normally" powered logic gate section. Running the gates off of -15V basically saves an op amp, and the logic chip doesn't really care as long as the voltage potential across the supply pins is the right polarity and within a certain range.
Just thought I'd chime in!
Tim (another "unusual" connection) Servo |
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Tim Servo
Joined: Jul 16, 2006
Posts: 924
Location: Silicon Valley
Audio files: 11
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| Posted: Tue May 15, 2007 9:07 am Post subject:
TH’s Quadrature Function Generator sync mod |
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| RF wrote: | Question for the brain trust here....
I built the QFG over the weekend - but...... Not having a 1458 in the parts bin I stuck in an LM358.
So the 'derived' output is indeed 90 degrees out of phase...but a bit jumpy . I played with the value of C1 and juggled a couple resistors to make it usable, but it's still a bit rough. Is this the issue Mr. Henry is referring to in the article re: the slow slew rate in the 1458 masking discontinuities?
Ooops. I just looked at the schematic again and realized I'm running it off +- 12 volts rather than the 15 specified. ummm....? Seems to work except for the derived being a bit rough...
Input? |
Hey RF,
Just thought I'd jump in again, as long as I'm awake and on line
You're absolutely right, Thomas uses the slow slew rate of the 1458 to filter some of the discontinuities in the waveform. The 1458 can't reproduce very high frequency info, and so acts as a bit of a low pass filter. This is a neat little trick, and you can get the same results with a 741 (but in a single package, of course). This is also a cautionary tale for people who go through and replace older op amps in vintage synths with modern units. Most of the time, this is okay, but you shouldn't replace an op amp with a different type unless you know a little about what's going on in the circuit. Waveshaping circuits (as you've seen) are the most likely to actually perform worse with a "better" op amp.
Tim (slewby doo) Servo |
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mono-poly
Joined: Jul 07, 2004
Posts: 937
Location: Rotterdam, Netherlands
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| Posted: Wed May 16, 2007 1:49 am Post subject:
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| funkyfarm wrote: | | Adam-V wrote: | Doepfer have got a VC Quadrature LFO planned for release in July.
Cheers,
Adam-V |
Yep ! but surely with sine waveforms...
maybe the same as Jim Patchell’s VC Quadrature Oscillator ? |
I wouldn't be surprised if it would be another Doepfer rip off. |
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