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 Forum index » DIY Hardware and Software » Ken Stone designs - CGS
Difference between CGS DUSG and Serge VCTimeGen?
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macumbista



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PostPosted: Sat Dec 17, 2011 2:53 pm    Post subject: Difference between CGS DUSG and Serge VCTimeGen? Reply with quote  Mark this post and the followings unread

I've been figuring that in the new Serge M-Class panels, the VCTimeGen Clock and VCTimeGen Osc modules are just using DUSG boards with some small modifications (maybe matched transistors?) and prepatched programming. Knowing those differences would help me get the most out of my CGS DUSG boards.

The one thing I can't work out is how the VCTimeGens do PulseWidthModulation, as indicated in this description:

Quote:
Left (Osc) cell:
Red Jack = VC Variable-Width Pulse Wave


and

Quote:
Right (TG) cell:
Red Jack = 50% duty-cycle Square Wave with rise/fall individually intoned


I haven't for the life of me been able to work out how this is done in the normal PWM way (i.e. that waveform/timbre changes without changing the pitch). Does anyone have any ideas on this?

In short: how to get a PWM output from the DUSG EndOut jack? Thanks!

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Last edited by macumbista on Sun Dec 18, 2011 6:00 am; edited 1 time in total
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macumbista



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PostPosted: Sat Dec 17, 2011 3:44 pm    Post subject: Reply with quote  Mark this post and the followings unread

Think I got it now.

Since you can always retrigger the SlopeGen from the SigIn jack, you can use the other SlopeGen to trigger the first and then modulate the pulse width of the EndOut of the second. Make sense? Still don't know what is meant by "individually intoned" rise and fall however...

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macumbista



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PostPosted: Sun Dec 18, 2011 5:31 am    Post subject: Reply with quote  Mark this post and the followings unread

It's the ME thread... Laughing

I had a big chat about this over at Muff's, have a look if you are interested.

Short answer: You can change the waveform/timbre while preserving the frequency by using one TimeGen/VCSlope unit as the timebase to trigger another, then playing with the Rise and Fall times of the second for waveshaping or PWM.

PWM/waveshaping cannot be done independent of frequency using only one TimeGen/VCSlope of the pair, however.

In case anyone's curious, I will try wiring my DUSG board as a VC TimeGen Clock by doing the following:

Left Cell:
Output = DCO
Cycle Switch = connect M and A
Gate = M
TrigIn = C (yes, the Input, not the TrigIn, the Cycle Switch already takes care of self-cycling. This way, a gate signal to TrigIn interrupts the cycle and can be used for waveshaping/pwm)
Freq = E
CV In = F

Right Cell:
Output = DCO
SigIn = C
Gate = M
Rise = H
Fall = K
CV In = F

Feel free to correct me if I am wrong. Or wish me luck!

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Last edited by macumbista on Fri May 04, 2012 6:36 am; edited 2 times in total
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PostPosted: Sun Dec 18, 2011 5:50 am    Post subject: Reply with quote  Mark this post and the followings unread

macumbista wrote:
Or wish me luck!


Laughing

Not really knowing what you talk about I'll wish you luck Smile

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macumbista



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PostPosted: Sun Dec 18, 2011 5:57 am    Post subject: Reply with quote  Mark this post and the followings unread

That's cool. Maybe you want to refile this thread in the CGS department, as it deals with Ken's CGS114 Dual Universal Slope Generator module, and the wiring I just posted might be helpful for others with the same PCBs.
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Blue Hell
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PostPosted: Sun Dec 18, 2011 6:02 am    Post subject: Reply with quote  Mark this post and the followings unread

macumbista wrote:
Maybe you want to refile this thread in the CGS department


Sure, done.

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Mongo1



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PostPosted: Sun Dec 18, 2011 10:08 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi,I actually do know what you're talking about, and I use the two-cell approach all the time. I find it to be the best way to control Low Pass Gates when I want to do something like a percussion beat. I use cell 1 to set up a low frequency oscillator, and then use that to trigger cell 2. The Output of that becomes the CV for the LPG. It works like magic....

I do that so often I'm thinking about trying to design something that maybe uses a 555 as the oscillator feeding another one as the pulse shaper. Put maybe 4 of those in one module and it would be sweeeeet...



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macumbista



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PostPosted: Mon Dec 19, 2011 3:52 am    Post subject: Reply with quote  Mark this post and the followings unread

Yeah that is exactly what I have in mind! Narrow, modulatable trigger pulses for things like LPGs. I'm glad I didn't just make this PWM solution up myself, and that it seems like what was intended with the design. Difficult to reverse-engineer a Serge only from the online documentation Laughing (Actually, that's not true, I do have two of Ken's VCS boards built and almost everything I know about slope generators comes from those...)

BTW, don't everyone go build from the wiring I posted above yet, still some bugs to work out. Will post again when it's ready.

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macumbista



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PostPosted: Tue Feb 28, 2012 7:04 pm    Post subject: Reply with quote  Mark this post and the followings unread

Having a terrible time with this. Both sections respond to a Sig In, but not to Trig In and the voltage control inputs behave very badly. Could this be related to my wiring experiment or something else? Transistors and diodes have all been checked for pin out/polarity...
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