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 Forum index » DIY Hardware and Software » YuSynth
Need some help LFO trimming (scope photos included)
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koenpepping



Joined: Jun 25, 2014
Posts: 8
Location: utrecht NL

PostPosted: Fri Jul 25, 2014 7:01 am    Post subject: Need some help LFO trimming (scope photos included) Reply with quote  Mark this post and the followings unread

Hi,

I am trying to trim my yusynth LFO, but it doesn't seem to work really well. (scope y is divided by 5v)

I've tried a lot but:

The LED is always on, it doesn't blink

The triangle looks more like a saw

Pulsewidth is varies from 0% to 10% (as you can see on the picture)

Sine doesn't really look like a sine (see picture)

what can i do?

thanks!


IMAG0928.jpg
 Description:
Saw
 Filesize:  600.81 KB
 Viewed:  471 Time(s)
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IMAG0928.jpg



IMAG0927.jpg
 Description:
Triangle
 Filesize:  751.63 KB
 Viewed:  359 Time(s)
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IMAG0927.jpg



IMAG0926.jpg
 Description:
Sine
 Filesize:  764.39 KB
 Viewed:  379 Time(s)
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IMAG0926.jpg



IMAG0925.jpg
 Description:
Pulse (on maximum pulsewidth, minimum is just a flat line)
 Filesize:  763.17 KB
 Viewed:  368 Time(s)
This image has been reduced to fit the page. Click on it to enlarge.

IMAG0925.jpg


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Andrej



Joined: Aug 25, 2016
Posts: 1
Location: Lithuania

PostPosted: Thu Aug 25, 2016 1:16 pm    Post subject: Reply with quote  Mark this post and the followings unread

hi everyone.

I know this topic is old, but same problems remain. i've got the same trimming problems. and my LFO2 oscillates at very high frequency, just like VCO. I used ICM7555 , TL071 and TL074. all parts were checked before soldering and all voltages are ok.

any help please?
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yusynth



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

PostPosted: Tue Sep 06, 2016 1:25 am    Post subject: Reply with quote  Mark this post and the followings unread

Are you sure you used a BC557 (PNP) for Q1 ?

For your scope shot what is the amplitude (V/square) and time scale (ms/square) ?

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Yves
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RyBowk



Joined: Nov 25, 2018
Posts: 33
Location: England

PostPosted: Mon Nov 18, 2019 3:46 am    Post subject: Reply with quote  Mark this post and the followings unread

I have the exact same issues as this, does anyone know the solutions at all yet? I have replaced all ic’s, transistors, caps. No change. My scope images are exactly the same as these. I am powering at 12v by the way many thanks Ryan
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