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picsynth
Joined: Oct 16, 2008 Posts: 27 Location: New Zealand
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JovianPyx
Joined: Nov 20, 2007 Posts: 1988 Location: West Red Spot, Jupiter
Audio files: 224
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Posted: Sun Feb 01, 2009 2:00 am Post subject:
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Is the sawtooth output amplitude the same regardless of input frequency? I'm guessing "yes"
I've messed with the 4046 and found that it's possible to make the tracking fast enough that proves the naysayers are just wrong. Good work.
My circuit (NOTE: NOT A SQUARE TO SAW CIRCUIT, ONLY A 4046 CIRCUIT) is here: http://home1.gte.net/res0658s/fatman/4046pll.html This receives a trackable input and produces several harmonically related outputs. It does, however, have the tracking characteristic requirements of the OP's circuit and can be adjusted. _________________ FPGA, dsPIC and Fatman Synth Stuff
Time flies like a banana. Fruit flies when you're having fun. BTW, Do these genes make my ass look fat? corruptio optimi pessima
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picsynth
Joined: Oct 16, 2008 Posts: 27 Location: New Zealand
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Posted: Sun Feb 01, 2009 1:36 pm Post subject:
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Yes the output amplitude is independant of input frequency.
I tried a number of components for the PLL loop filter before arriving at 2x50k and 2.2uF. The circuit works well up to B6.
These components are very critical to operation of the circuit. Too low values for the resistors and you loose the lower harmonics of your saw and it turns to a pulse or PLL skips around, too high and you get portamento (which is actually quite interesting effect).
Maybe the naysayers gave up because getting the loop filter right is tricky.
There is a slight distortion of the waveform output on frequency change even with these components.
I can see this on a scope but not hear it when listening to the sawtooth as I think it results in some odd/even harmonics being injected which are present in the saw anyway.
So what would you use the circuit for ? Converting output of digital logic (eg a PIC, CMOS etc...) into a great sounding sawtooth !
Kevin |
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JovianPyx
Joined: Nov 20, 2007 Posts: 1988 Location: West Red Spot, Jupiter
Audio files: 224
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Posted: Sun Feb 01, 2009 1:57 pm Post subject:
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Yeah, the tricky factor of the loop filter is why I made mine adjustable. It will make a chirp for large jumps like 3 octaves, but usually, there's no trace of any tracking delay. And yes, the portamento is cool, I use that intentionally - sounds cool when it's mixed with the driving signal because if the driving signal does not have portamento or portamento with different timing, there's a dissonence at the note attack that is interesting. _________________ FPGA, dsPIC and Fatman Synth Stuff
Time flies like a banana. Fruit flies when you're having fun. BTW, Do these genes make my ass look fat? corruptio optimi pessima
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moylando
Joined: Dec 11, 2008 Posts: 13 Location: Philadelphia
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Posted: Wed May 13, 2009 12:10 pm Post subject:
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Grant Richter from Wiard gets a ramp wave directly from the capacitor of the 4046 in his WoggleBug. I believe he credits someone else with the idea. Google for the schematic. |
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droffset
Joined: Feb 02, 2009 Posts: 515 Location: London area
Audio files: 2
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Posted: Sun May 17, 2009 5:46 pm Post subject:
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This looks cool, I'll try to work it into my Lunetta machine |
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Rolbista
Joined: Nov 17, 2012 Posts: 23 Location: Poland
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Posted: Fri Mar 01, 2013 1:34 pm Post subject:
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moylando wrote: | Grant Richter from Wiard gets a ramp wave directly from the capacitor of the 4046 in his WoggleBug. I believe he credits someone else with the idea. Google for the schematic. |
http://pugix.com/synth/wp-content/uploads/2008/03/woggle-wog.pdf is this the schematic you're referring to? Which part of the circuit would convert a square to a sawtooth, I can't see any input pin on the 4046 for it. I think I'll try the circuit at the top of this thread eventually, but I'm trying to save board space in the project I'm working on. Are there any other SQR-> SAW converters circuits? like a 555 generator clocked externally?
EDIT:
Oh, wait, is the input the pin labeled "smooth tone SQ"? Which parts are essential? I don't really need the CV shaping parts, just a converter |
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elmegil
Joined: Mar 20, 2012 Posts: 2177 Location: Chicago
Audio files: 16
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Rolbista
Joined: Nov 17, 2012 Posts: 23 Location: Poland
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Posted: Wed Mar 06, 2013 9:52 am Post subject:
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Ok, tried the 4046/4024 circuit and it works. The output is more of a "sawtoothoid" really, kinda looks like a reversed ADSR symbol. When I play legato it keeps the shape, but when I play separate notes it sometimes begins as a square for a split second to form into a sawtooth later. Is that a thing of trimming the 50k resistors and the 2,2uF cap? Also will it run on 12V, becauce my comparators forming a square wave run on 12 and there is a big difference in amplitude beetween saw and square (saw being much lower)
By the way, i used a 150pF cap instead of 180pF |
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picsynth
Joined: Oct 16, 2008 Posts: 27 Location: New Zealand
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Posted: Mon Sep 30, 2013 2:18 pm Post subject:
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Hi
The circuit was intended for a constant input ie a square wave that does not cut out after each note. The VCA would be added after this circuit. It will jump around if the input cuts off. It does handle changes in frequency well ie playing different notes, but not complete cut off.
Yes you can tune the 50k resistors and 2.2 uf cap - that is fun and can result in amazing portamento and effects etc if you want them
The circuit will run from 12 V
Kevin
PICSYNTH
http://picsynth.000space.com |
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