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 Forum index » DIY Hardware and Software
LFO help
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killerbite



Joined: Mar 21, 2019
Posts: 4
Location: aus

PostPosted: Thu Mar 21, 2019 7:15 pm    Post subject: LFO help Reply with quote  Mark this post and the followings unread

TLDR im a fucking dumb cunt and cant always read schematics
i found this LFO
( http://electro-music.com/forum/phpbb-files/lfo_229.jpg )
on this site months ago and ive started putting it together but ive lost the forum post and cant find it to save my life i only have this image to go off and i dont understand how to wire up the pots could someone please link me to the original thread please or tell what to do
if the image had everything layed out i would be fine but im so new to all this that im having a hard time with only half done schems that assume u know wtf to do or the IC thats used is broken our rather than just showing what pins from the ic go wear its all the internal stuff going every wear and oh god im so confused

something like this i can easily understand, https://docs.google.com/viewerng/viewer?url=http://www.synthrotek.com/wp-content/uploads/2014/02/APC.pdf
this lfo i can not, http://electro-music.com/forum/phpbb-files/lfo_229.jpg

i have made the baby 8 + apc seqencer but thats it so far those schematics wear done really well and wear super easy to understand unlike this LFO that im struggling to work out

thanks

Last edited by killerbite on Thu Mar 21, 2019 7:23 pm; edited 1 time in total
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killerbite



Joined: Mar 21, 2019
Posts: 4
Location: aus

PostPosted: Thu Mar 21, 2019 7:17 pm    Post subject: Reply with quote  Mark this post and the followings unread

also this LFO schem having 2 different layouts on it really messes with my head like some parts are on the lower diagram but they are not on the top diagram like wtf am i looking at anyone have a more clear schematic?
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Blue Hell
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Joined: Apr 03, 2004
Posts: 22857
Location: The Netherlands, Enschede
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PostPosted: Thu Mar 21, 2019 7:26 pm    Post subject: Reply with quote  Mark this post and the followings unread

Made the image link clickable .. erm ... that is fokking messy indeed. the drawing it is .. I'm not getting it after a couple of minutes ... and sorry, dont recall where it came from .. looks oolde .. hope someone remembers.

And also welcome

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also .. could someone please turn down the thermostat a bit.
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killerbite



Joined: Mar 21, 2019
Posts: 4
Location: aus

PostPosted: Thu Mar 21, 2019 7:36 pm    Post subject: Reply with quote  Mark this post and the followings unread

ok so its not just me then XD, it was just (what i thought) was going to be a simple LFO :/

and cheers been lurking around for awhile now hahah
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gabbagabi



Joined: Nov 29, 2008
Posts: 539
Location: Berlin by n8
Audio files: 23

PostPosted: Thu Mar 21, 2019 11:10 pm    Post subject: Reply with quote  Mark this post and the followings unread

hm,
it is somewhat easy recognice-able
as a original nicolas1234 circuit Smile


and of course
welcome to the show
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comrade_zero



Joined: Mar 05, 2009
Posts: 66
Location: arizona
Audio files: 4

PostPosted: Thu Mar 21, 2019 11:25 pm    Post subject: Reply with quote  Mark this post and the followings unread

Ok, so for this particular LFO you have two potentiometers, one that controls the rate (frequency) of oscillation, the other controls the shape of the wave ("skew"). The skew control will shape the triangle wave output for a saw to a tri to a ramp. If you are building this on breadboard than ignore the top layout for now and we will focus on the schematic (also two diodes in the schematic are not shown on the layout, the author suggests soldering them directly to the skew pot, this is probably a source of your confusion). The IC is an LM324 quad op-amp. (Pin numbers would be helpful here...) But about those pots... The rate control will connect one side to the output of U1a (lm324 pin 1), the wiper (middle pot pin) is connected to R5(47k resistor) and the other side to 0v(gnd). The Skew control wiper (middle pin) is connected the the output of U1b (lm324 pin 7), one side is connected to the diode D1, the other to D2. These diodes do not appear on the layout (see above.) Ken Stone has a similar skewable LFO, and if I remember correctly Ray Wilson did as well. The basic LFO is the Scmitt trigger/integrator oscillator that yields a triangle and pulse (square) output. The simplest implementation of this type of oscillator is probably Thomas Henry's: http://electro-music.com/forum/topic-63709.html
Good luck, hope this helps.
c_z
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comrade_zero



Joined: Mar 05, 2009
Posts: 66
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PostPosted: Thu Mar 21, 2019 11:44 pm    Post subject: Reply with quote  Mark this post and the followings unread

Original thread for this LFO is here: http://electro-music.com/forum/topic-32372.html

The Ken Stone version of a similar LFO is here: http://www.elby-designs.com/webtek/cgs/cgs58/cgs58_lfo.html

The Ray Wilson version (a little more complex, with an OTA-based sine waveshape and indicator LED) is here: http://musicfromouterspace.com/forums.html?MAINTAB=SYNTHDIY&PROJARG=OLDIESBUTGOODIES/VOLTAGEMIXER/voltagedist2.html&VPW=1350&VPH=524
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JovianPyx



Joined: Nov 20, 2007
Posts: 1854
Location: West Red Spot, Jupiter
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PostPosted: Fri Mar 22, 2019 7:44 am    Post subject: Reply with quote  Mark this post and the followings unread

One of the reasons there is a ground symbol is both to keep a schematic cleaner and to reinforce the fact that a ground reference (or current sink or source to/from ground) is being used. Yes, the schematic is cluttered. I often will redraw such schematics for my own use. It's interesting how the grounds are collected with a conductor line labeled 0V and there are no references to the other power rails.

At least it's using a real dual supply instead of virtual ground, but that's another story.

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killerbite



Joined: Mar 21, 2019
Posts: 4
Location: aus

PostPosted: Wed Mar 27, 2019 7:26 pm    Post subject: Reply with quote  Mark this post and the followings unread

hey guys

sorry for late reply but thanks for you replys i will go over those threads Smile and yeah i am doing everything on breadboard first before i commit to soldering it to a perf board

i have managed to make this sequencer + apc http://electro-music.com/forum/phpbb-files/apc_187.png and it works amazing the only problem im having is with the pots, no matter what kind of pot i use (20k, 50k, 100k, ect) only about 1/3rd of the pot has and range and the other 2/3rds has nothing, its rather weird
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