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 Forum index » Clavia Nord Modular » G2 Building Blocks
Variable Clock Generator Gate Pulse Width Output
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varice



Joined: Dec 29, 2004
Posts: 961
Location: Northeastern shore of Toledo Bend
Audio files: 29
G2 patch files: 54

PostPosted: Mon Apr 16, 2012 8:27 pm    Post subject: Variable Clock Generator Gate Pulse Width Output
Subject description: with a duty cycle that remains constant with tempo change
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Here is a little patch trick that I have been using to stretch the very short trigger output of the Clock Generator module into a longer gate signal. The neat part of this particular trick is using a specially configured Decay Envelope module to modulate the time parameter of a Logic Delay module. This configuration results in the clock gate pulse duty cycle output of the Logic Delay module remaining relatively constant over the full range of the Clock Generator module tempo settings.

A problem though is that the time modulation control setting of the Logic Delay module will result in a non-linear pulse width setting (e.g. setting this Logic Delay control at the mid point results in a clock pulse duty cycle that is much less than 50/50 as may be desired). A more linear pulse width control is accomplished by adding a Constant Level module (in unipolar mode) patched through a Static Shaper module (in Inv x2 mode) connected to the AM input of the EG module. With this more linear control at any tempo setting:

1. A Control Level value of 64 results in the maximum gate pulse width.
2. A value of 48 gives an approximate 75/25 duty cycle for the Gate PW, which is about the standard duration of a note in musical notation.
3. A value of 32 gives an approximate 50/50 duty cycle Gate PW.
4. A value of 0 gives the minimum Gate PW.

Another issue is that when increasing the Clock tempo from very slow to faster BPM rates with the Gate PW set to max, a new Clock pulse can occur before the Logic Delay has timed out and the output goes low. This results in an expected Clock trigger being missed. The Flip Flop and AND Gate logic modules are patched in a way to force a gate retrigger with every Cock pulse even if the Logic Delay has not timed out.

If you don’t need linear Gate PW control and forced gate retrigger with tempo increases, a minimal version of this patch trick would be to use only the EG and Logic Delay modules with the Clock, adjusting only the modulation time parameter of the Logic Delay module to set the clock gate pulse width. The other parameters of the EG and Delay modules should not be changed.


Clock Gate PW2.pch2
 Description:
Variable Clock Generator Gate Pulse Width Output with a duty cycle that remains constant with tempo change

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 Filename:  Clock Gate PW2.pch2
 Filesize:  3.32 KB
 Downloaded:  4264 Time(s)


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Last edited by varice on Tue Apr 17, 2012 3:13 pm; edited 2 times in total
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iPassenger



Joined: Jan 27, 2007
Posts: 1067
Location: Sheffield, UK
Audio files: 5
G2 patch files: 78

PostPosted: Tue Apr 17, 2012 10:23 am    Post subject: Reply with quote  Mark this post and the followings unread

Why the envelope?

What about this: Attached.

You use one pulse to extract the leading edge (so the tempo doesn't affect note length) and then the second pulse to set the length.


clock_gate_pw2_447[1].pch2
 Description:

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 Filename:  clock_gate_pw2_447[1].pch2
 Filesize:  2.97 KB
 Downloaded:  4173 Time(s)


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varice



Joined: Dec 29, 2004
Posts: 961
Location: Northeastern shore of Toledo Bend
Audio files: 29
G2 patch files: 54

PostPosted: Tue Apr 17, 2012 1:42 pm    Post subject: Reply with quote  Mark this post and the followings unread

Sorry for the confused wording of the first paragraph of the first post. I have edited it to hopefully be clearer.

In other words, I want the pulse width out of the Logic Delay to change to match any tempo change (that’s why the EG is modulating the Delay time). This will give a relatively constant duty cycle (ratio of gate on to gate off) with any tempo.

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PostPosted: Tue Apr 17, 2012 2:34 pm    Post subject: Reply with quote  Mark this post and the followings unread

Ah sorry, I see what you mean. Smile Wasn't paying enough attention. Embarassed
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varice



Joined: Dec 29, 2004
Posts: 961
Location: Northeastern shore of Toledo Bend
Audio files: 29
G2 patch files: 54

PostPosted: Tue Apr 17, 2012 3:18 pm    Post subject: Reply with quote  Mark this post and the followings unread

No, it was my fault for incorrectly stating that the pulse width instead of the duty cycle remained consistent with tempo changes. Even the wording in the patch name bars and textpad was wrong! Embarassed I have just now replaced the patch in the original post.
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varice
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varice



Joined: Dec 29, 2004
Posts: 961
Location: Northeastern shore of Toledo Bend
Audio files: 29
G2 patch files: 54

PostPosted: Tue May 08, 2012 7:56 pm    Post subject: Reply with quote  Mark this post and the followings unread

Here are two new versions. These use a ZeroCnt module instead of an EG for more accurate clock rate to control signal conversion. (Thanks Ross!) ref:

http://electro-music.com/forum/topic-53307.html

The “c” version has a much more linear control setting of the clock duty cycle.


Clock Gate PW2b.pch2
 Description:

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 Filename:  Clock Gate PW2b.pch2
 Filesize:  3.2 KB
 Downloaded:  4287 Time(s)


Clock Gate PW2c.pch2
 Description:
Linear control of Clock Duty Cycle

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 Filename:  Clock Gate PW2c.pch2
 Filesize:  3.39 KB
 Downloaded:  4270 Time(s)


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