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 Forum index » DIY Hardware and Software » Lunettas - circuits inspired by Stanley Lunetta
Simple LFO schematic, opinions?
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Joined: Feb 02, 2010
Posts: 198
Location: California

PostPosted: Tue May 11, 2010 12:50 am    Post subject: Reply with quote  Mark this post and the followings unread

Sorry... bumping this thread from long ago...

Trying to build a LPF and LFO from one 4069. Got the LPF working, tried building the LFO above (fatman LFO) can't seem to get it to work - seems I've got it all set up correctly on the breadboard.

Mine is 4069UBP which I believe means something about unbuffered or something. Could that be the issue?

Also, I was testing it by putting an LED between the output from the pot and ground... not sure if my thinking is correct there... - my hope is to light an LED with it (to eventually control a home made vactrol to sweep the filter).

Any ideas?

EDIT: to clarify, I am getting no oscillation. I measure between 2-3 volts DC at the output - varying depending on the frequency pot's setting (set low = lower voltage). It will light a LED, but no oscillating fluctuation in brightness.
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Joined: Feb 02, 2010
Posts: 198
Location: California

PostPosted: Wed May 12, 2010 1:07 am    Post subject: Reply with quote  Mark this post and the followings unread

Searching around the internet I found a thread on another board that referred to this 4069 LFO and someone who was having trouble with it. The suggestion there was to try lowering the resistor from pin 1 to 6. I tried it and it works.

The value that worked best for me is about 80k Ohms. The higher I go, the deeper the sweep, but at a certain point, it latches and won't oscillate anymore. Also, there is a short range at the high end (last 5% or so) of the 100k output depth knob that also causes the LFO suddenly slow down and latch high. It is annoying, but I can live with it. Filter + LFO from one 4069, sweet. I've got them linked using a LED/LDR combo.

FWIW for anyone who searches in the future and wants to troubleshoot values, I am running at +12V and ended up with a 2.2uF cap rather than the 1.3uF. It can do a really nice slow sweep on up to near audio rate.
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Technoshaman



Joined: Nov 04, 2010
Posts: 7
Location: Istanbul

PostPosted: Fri Dec 17, 2010 7:15 am    Post subject: Reply with quote  Mark this post and the followings unread

Dear friends,

I've recently built and tried the first circuit in this thread (the one with 3 741's). It worked nicely as a Proteus simulation and also with my +/-15V supply and Thomas Henry's VCO-1. I'm attaching the screenshots and the PCB as a PDF document.

Posted Image, might have been reduced in size. Click Image to view fullscreen.

Posted Image, might have been reduced in size. Click Image to view fullscreen.

http://www.technoshamanarchist.net/pictures/LFO_PCB.pdf

Hope someone finds it useful.

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-minus-



Joined: Oct 26, 2008
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PostPosted: Fri Dec 17, 2010 1:44 pm    Post subject: Reply with quote  Mark this post and the followings unread

I'll have a look at building this next year I think....

I just wanted to say I really like that PCB diagram!!!! Thanks for posting this. It looks so nice! I really ought to do some etching next year.
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RF



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PostPosted: Fri Dec 17, 2010 4:30 pm    Post subject: Reply with quote  Mark this post and the followings unread

2011 - In which Minus embraces the op-amp.
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Blue Hell
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PostPosted: Fri Dec 17, 2010 5:04 pm    Post subject: Reply with quote  Mark this post and the followings unread

RF wrote:
2011 - In which Minus embraces the op-amp.


Laughing

good things happen Exclamation

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-minus-



Joined: Oct 26, 2008
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PostPosted: Fri Dec 17, 2010 5:16 pm    Post subject: Reply with quote  Mark this post and the followings unread

Very Happy Ha ha! I've been embracing the op amp here for a while now. I have several windows open as I type regarding op amps Wink . The main stumbling point has been powering them.
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Blue Hell
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PostPosted: Fri Dec 17, 2010 5:48 pm    Post subject: Reply with quote  Mark this post and the followings unread

-minus- wrote:
The main stumbling point has been powering them.


It is handy to have dual + / - power supply with regulated voltage and settable current limiting (to prevent accidents). It's not directly musical, but well worth to buy or DIY it.

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Technoshaman



Joined: Nov 04, 2010
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PostPosted: Sat Dec 18, 2010 3:48 am    Post subject: Reply with quote  Mark this post and the followings unread

Thank you -minus- and everyone else Smile Happy to see someone's gonna use it "one day" Wink I'm about to head out to get a box for this and the Jürgen Haibles WASP VCF clone. If anyone wants to see (and / or criticize) how the VCO-1 sounds, I posted a video here with pictures. Under TH designs...

Happy soldering!

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tubeampguy



Joined: Oct 29, 2009
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PostPosted: Mon Jan 10, 2011 8:50 pm    Post subject: Reply with quote  Mark this post and the followings unread

Has anyone here used a LM348 for a multi-LFO (squarwave only) circuit for Eurorack?
I'm wondering if the 12v rail in my Monorocket can handle the draw Question
Any suggestions is apprenticed! thanks!
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Mubo



Joined: Jul 21, 2008
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PostPosted: Tue Jan 11, 2011 10:42 pm    Post subject: output jacks
Subject description: how to hook up?
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@ Technoshaman

where do the grounds for the output jacks get hooked up?

thanks!

-mubo
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Technoshaman



Joined: Nov 04, 2010
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PostPosted: Tue Jan 11, 2011 11:33 pm    Post subject: Reply with quote  Mark this post and the followings unread

@ mubo: Vss Smile
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Mubo



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PostPosted: Wed Jan 12, 2011 3:48 am    Post subject: Reply with quote  Mark this post and the followings unread

ok, thats how i have it on my breadboard, but wanted to check since i didnt see extra ground connections on your pcb....

Thanks
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Technoshaman



Joined: Nov 04, 2010
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PostPosted: Wed Jan 12, 2011 4:05 am    Post subject: Reply with quote  Mark this post and the followings unread

Sorry, I thought it would be obvious in the schematic. And IMHO, This LFO is not the best. I'm not very happy with the sine output, and the speed won't go up as much (I think modifying C1 should help, haven't tried that yet, since, as a digital designer, I'm more into a MOS6581 based synth now) to create a Theremin like vibrato Neutral Good luck Smile
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qzzk_



Joined: Feb 24, 2011
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PostPosted: Thu Feb 24, 2011 2:58 pm    Post subject: Reply with quote  Mark this post and the followings unread

hI guys

Technoshaman, i builded in a bradboard and its working but there is a dramatic diference in volume between the square wave (so far the most loud) and the triagle and sine waves.
Any idea why?

thanks
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Technoshaman



Joined: Nov 04, 2010
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PostPosted: Thu Feb 24, 2011 3:04 pm    Post subject: Reply with quote  Mark this post and the followings unread

qzzk_ wrote:
hI guys

Technoshaman, i builded in a bradboard and its working but there is a dramatic diference in volume between the square wave (so far the most loud) and the triagle and sine waves.
Any idea why?

thanks


As far as I know, that's usually how it is due to the structure of the waves.

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Ajax



Joined: Apr 05, 2010
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PostPosted: Thu Feb 24, 2011 4:32 pm    Post subject: Reply with quote  Mark this post and the followings unread

Technoshaman wrote:
qzzk_ wrote:
hI guys

Technoshaman, i builded in a bradboard and its working but there is a dramatic diference in volume between the square wave (so far the most loud) and the triagle and sine waves.
Any idea why?

thanks


As far as I know, that's usually how it is due to the structure of the waves.


Yep, that's right. Square waves have way more harmonic content than sine or triangle waves.
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tubeampguy



Joined: Oct 29, 2009
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PostPosted: Thu Feb 24, 2011 10:12 pm    Post subject: Reply with quote  Mark this post and the followings unread

tubeampguy wrote:
Has anyone here used a LM348 for a multi-LFO (squarwave only) circuit for Eurorack?
I'm wondering if the 12v rail in my Monorocket can handle the draw Question
Any suggestions is apprenticed! thanks!

bump! Shocked
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qzzk_



Joined: Feb 24, 2011
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PostPosted: Fri Feb 25, 2011 4:21 pm    Post subject: Reply with quote  Mark this post and the followings unread

Ok, thanks

But, there is not a way or technic to equilibrate the volumes of the waves?? any sugention? sorry if the question is so obvius or basic, but i am new building this kind of staff.

thanks guys
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qzzk_



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PostPosted: Fri Feb 25, 2011 5:40 pm    Post subject: Reply with quote  Mark this post and the followings unread

Another question, will be possible to add an CV to this simple LFO?? i am thinking in control it from another simple module.

thanks!
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Psyingo



Joined: Jun 11, 2009
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PostPosted: Mon Feb 28, 2011 7:45 am    Post subject: Reply with quote  Mark this post and the followings unread

qzzk_ wrote:
Another question, will be possible to add an CV to this simple LFO?? i am thinking in control it from another simple module.

thanks!


vactrols
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Rolbista



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PostPosted: Wed Dec 05, 2012 2:57 pm    Post subject: Reply with quote  Mark this post and the followings unread

OK, I know it's a terrible sin to necropost, but I'm having some problems with the 4069 LFO. Works, I put both waveforms on a switch, but I get pretty loud ticking, as if it bled through to the signal. I put together a simple tremolo based on a single transistor boost circuit with a vactrol on the input. The LED is connected only to the output of the lfo, with separate ground , the boost is powered from a battery, the LFO from an adapter, but there still is audiblo LFO noise, especially when the fuzz before the tremolo is engaged, then, the noise becomes unbearable. I put a 100uF cap from a 6V voltage regulator to pin 8 of the 4069, in parallel with a 180ohm resistor as i read on the net, but that doesn't help the noise at all... Maybe it's because the fuzz before the tremolo is powered from the same adapter as the LFO?
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JingleJoe



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PostPosted: Thu Dec 06, 2012 1:27 am    Post subject: Reply with quote  Mark this post and the followings unread

Rolbista wrote:
OK, I know it's a terrible sin to necropost,

where the hell did you get that idea?

I don't know why you have a resistor in series with the power supply filter cap, just put a nice big cap between +V and Ground. That will probably help. Also you may have mis-connected something like a missing ground connection.

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PostPosted: Thu Dec 06, 2012 4:35 am    Post subject: Reply with quote  Mark this post and the followings unread

I love necroposts! Twisted Evil
They bring up really great ideas which I missed the first time round. Very Happy

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Rolbista



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PostPosted: Thu Dec 06, 2012 2:10 pm    Post subject: Reply with quote  Mark this post and the followings unread

says here: https://sites.google.com/site/flofxdiy/deticking-lfo that I should put a cap to ground from the power supply and a 100ohm resistor from V+ to power pin on the chip to let the cap accumulate some "spare current". I also read that power ripples from sudden current demands of the LFO cause some RF noise, could they get through to the audio path from a power rail running beside it inside the enclosure?
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