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 Forum index » DIY Hardware and Software » YuSynth
Troubleshooting the VCLFO (1)
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kkissinger



Joined: Mar 28, 2006
Posts: 1354
Location: Kansas City, Mo USA
Audio files: 42

PostPosted: Fri Apr 29, 2011 5:33 am    Post subject: Re: Just built two VCLFOs Reply with quote  Mark this post and the followings unread

kkissinger wrote:
Also, on the LOW frequency range, I get a large offset voltage. Anyway, once I get non-polarized in place I hope this takes care of the symptoms.


Just to follow up: I reviewed the schematic and found that I had missed that the VCLFO has separate offset adjustments for the low and high ranges. Thus, the offset problem was nothing more than a trim adjustment.

Thus, the only outstanding issue is the sync issue -- not a huge issue and could almost be a "feature". Smile

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kupfer_m



Joined: Oct 14, 2010
Posts: 48
Location: Belgium

PostPosted: Mon May 02, 2011 8:25 am    Post subject: Reply with quote  Mark this post and the followings unread

yusynth wrote:
LektroiD wrote:
The spikes are really obvious through a VCF or VCA. Any way to tame them?

Try and change the tantalum cap until you minimize the glitch.


I have the same problem with my VC-LFO2. But I also get spikes on the x1 setting. Will try with some other capacitors.
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LektroiD



Joined: Aug 23, 2008
Posts: 1018
Location: Scottish Borders
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G2 patch files: 2

PostPosted: Wed Jun 29, 2011 4:44 am    Post subject: Reply with quote  Mark this post and the followings unread

kupfer_m wrote:
yusynth wrote:
LektroiD wrote:
The spikes are really obvious through a VCF or VCA. Any way to tame them?

Try and change the tantalum cap until you minimize the glitch.


I have the same problem with my VC-LFO2. But I also get spikes on the x1 setting. Will try with some other capacitors.


did the other capacitors work?

Just a thought, this thread could maybe merge with the other VCLFO one, since it's the same issue

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kupfer_m



Joined: Oct 14, 2010
Posts: 48
Location: Belgium

PostPosted: Wed Jun 29, 2011 9:02 am    Post subject: Reply with quote  Mark this post and the followings unread

No, still those nasty clicks...
Tried a MAXIM 7555 (more expensive) but still the same.
One day I will find it Wink
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vinnui



Joined: Jun 12, 2009
Posts: 19
Location: Hungary

PostPosted: Mon Jul 04, 2011 9:07 am    Post subject: Reply with quote  Mark this post and the followings unread

I'm building 3 VC-LFO-2s, and today i've checked the waveforms of my first LFO build. The spikes were here. I've found, that i've used a NE555, which i've replaced with a ICM7555CN (I think it's a Philips part). After a complete recalibration procedure, the spikes are gone.
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adambee7



Joined: Apr 04, 2009
Posts: 420
Location: united kingdom

PostPosted: Mon Jul 04, 2011 1:57 pm    Post subject: Reply with quote  Mark this post and the followings unread

ive noticed on the schematics that there is no current limiting resistor going to the power pin of the 555. Would this be worth adding. usually its 100ohms. Very Happy Very Happy
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yusynth



Joined: Nov 24, 2005
Posts: 1314
Location: France

PostPosted: Tue Jul 05, 2011 4:05 am    Post subject: Reply with quote  Mark this post and the followings unread

adambee7 wrote:
ive noticed on the schematics that there is no current limiting resistor going to the power pin of the 555. Would this be worth adding. usually its 100ohms. Very Happy Very Happy

This is only valid if one uses the non CMOS version of the 555 ! Here we are using a CMOS 555 and this resistor is of no use.

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adambee7



Joined: Apr 04, 2009
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PostPosted: Tue Jul 05, 2011 10:10 am    Post subject: Reply with quote  Mark this post and the followings unread

thanks yves Very Happy . now to find some phillips 555. Very Happy Very Happy
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gibrancurtiss



Joined: Mar 16, 2016
Posts: 22
Location: brazil

PostPosted: Sat Apr 08, 2017 6:57 pm    Post subject: changed C5 Reply with quote  Mark this post and the followings unread

Changed the C5 from 47pf with other values 470pf and 1K.


vclfo-1.jpg
 Description:
47pf C5
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vclfo-1.jpg



vclfo-3.jpg
 Description:
47pf C5 zoomed to 50us
 Filesize:  122.59 KB
 Viewed:  309 Time(s)
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vclfo-3.jpg



vclfo-5.jpg
 Description:
1k C5
 Filesize:  153.44 KB
 Viewed:  273 Time(s)
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vclfo-5.jpg



vclfo-6.jpg
 Description:
1k C5 zoomed to 50us
 Filesize:  138.84 KB
 Viewed:  290 Time(s)
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vclfo-6.jpg


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