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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Fri Feb 27, 2009 9:34 am Post subject:
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Check that you soldered the jumper that connects pin1 of the 7555 to the ground. _________________ Yves |
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joshco
Joined: Nov 14, 2008 Posts: 55 Location: germany
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Posted: Fri Feb 27, 2009 10:26 am Post subject:
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all jumpers are soldered and i have tried diffrent 7555 chips... |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Fri Feb 27, 2009 12:09 pm Post subject:
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Have you correctly connected the range switch (as shown on the wiring diagram) ? Make sure that the wire the closest to the 7555 goes to the middle lug of the switch and the two other wires to the extreme lugs (upper and lower) of the switch. _________________ Yves |
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joshco
Joined: Nov 14, 2008 Posts: 55 Location: germany
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Posted: Sat Feb 28, 2009 5:15 am Post subject:
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yusynth wrote: | Have you correctly connected the range switch (as shown on the wiring diagram) ? Make sure that the wire the closest to the 7555 goes to the middle lug of the switch and the two other wires to the extreme lugs (upper and lower) of the switch. |
Yes, the switch is connected like in the wiring diagramm. The Pots and rotary switches, too.Sebo had some difficulties with the switch, but they are conected to the caps and trimmers like in the schematic... |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Sat Feb 28, 2009 5:20 am Post subject:
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OK to this point there nothing much that can be done without an oscilliscope.
Can you use the sondboard of your PC and an oscilloscope software to check what's happening at pin 5 and 7 of U2b. _________________ Yves |
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joshco
Joined: Nov 14, 2008 Posts: 55 Location: germany
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Posted: Sat Feb 28, 2009 6:31 am Post subject:
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here is the graph of pin5 (upper) and pin 7 (lower), looks rather good...
havent adjusted the time and amplitude |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Sat Feb 28, 2009 6:37 am Post subject:
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No it does not look good, I don't now what is the time base of the graphs but to me it looks like 50Hz hum.
You should have a clean rising sawtooth.
Try changing the BC557B. _________________ Yves |
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joshco
Joined: Nov 14, 2008 Posts: 55 Location: germany
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Posted: Sat Feb 28, 2009 6:45 am Post subject:
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i understand, i´ll have to go to the shop for a bc557, ill reply when i have some.
by now a big thanks for your support |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Sat Feb 28, 2009 7:13 am Post subject:
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Make sure it's a BC557C the C at the end does matter here !
[EDIT] Yes, my mistake : READ BC557B B DOES MATTER HERE[/EDIT] _________________ Yves Last edited by yusynth on Sun Mar 01, 2009 3:24 am; edited 1 time in total |
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Sebo
Joined: Apr 27, 2007 Posts: 564 Location: Argentina
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Posted: Sat Feb 28, 2009 1:57 pm Post subject:
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yusynth wrote: | Make sure it's a BC557C the C at the end does matter here ! |
Sorry, shouldn't be a BC557B? _________________ Sebo
---------------------------------------
My Music:
https://www.facebook.com/cosaquitos/ |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Sun Mar 01, 2009 3:24 am Post subject:
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Sebo wrote: | yusynth wrote: | Make sure it's a BC557C the C at the end does matter here ! |
Sorry, shouldn't be a BC557B? |
Yes, my mistake : READ BC557B B DOES MATTER HERE _________________ Yves |
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joshco
Joined: Nov 14, 2008 Posts: 55 Location: germany
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Posted: Mon Mar 02, 2009 3:09 pm Post subject:
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yes, I have taken the bc557b as described in the BOM, however, it still does not work. Again, a new 7555 is also installed. |
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joshco
Joined: Nov 14, 2008 Posts: 55 Location: germany
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Posted: Tue Mar 03, 2009 12:11 pm Post subject:
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well, as i checked my resistors box i recognized that there were some wrong values in the box, next thing is to check the correct values at the pcb, maybe there is something wrong... |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Tue Mar 03, 2009 12:16 pm Post subject:
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Hi
Yes a thorough check of the components and solder pads may be the solution as it seems that everything is correct upto Q1 _________________ Yves |
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Thalassa
Joined: Jan 27, 2006 Posts: 95 Location: Spain
Audio files: 5
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Posted: Wed Mar 04, 2009 3:53 pm Post subject:
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Hello Yves , I have a question also about the LFO.
There's a problem with the number of capacitors. According to the "list of materials" , there're only 2 100nF capacitors ( in the schematic also ) , but in the component layout there're 4 of this capacitors.
And also in the version 1 , C6 is supposed to be off board , but on the wiring diagram there's no capacitor and also on the schematic there isn't C6 capacitor.
Thanks _________________ http://www.corsynth.com |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Wed Mar 04, 2009 4:22 pm Post subject:
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Thalassa wrote: | Hello Yves , I have a question also about the LFO.
There's a problem with the number of capacitors. According to the "list of materials" , there're only 2 100nF capacitors ( in the schematic also ) , but in the component layout there're 4 of this capacitors. |
These are filter caps connected close the power supply pins of the ICs. Just add them as shown on the component layout diagram.
Thalassa wrote: | And also in the version 1 , C6 is supposed to be off board , but on the wiring diagram there's no capacitor and also on the schematic there isn't C6 capacitor. |
For LFO1, C6 is not required since there is no SYNC circuit in this version, I will correct these minor typos.
Thanks for reporting these. _________________ Yves |
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Thalassa
Joined: Jan 27, 2006 Posts: 95 Location: Spain
Audio files: 5
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Thu Mar 05, 2009 12:53 am Post subject:
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I made the update on my site for C6 and other filtering caps... _________________ Yves |
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Thalassa
Joined: Jan 27, 2006 Posts: 95 Location: Spain
Audio files: 5
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Minimalist
Joined: Nov 21, 2008 Posts: 9 Location: NZ
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Posted: Thu May 28, 2009 6:37 am Post subject:
LFO sine waveform like a triangle wave |
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Hi Yves
Thanks for your generous sharing, I've built one of your LFO version 2, it all works well except the sine waveform isn't right. It is adjustable but is comming out like a pure triangle wave with no rounding, all the other waveforms seem right.
Any suggestions where to look?
thanks Marcus |
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Thalassa
Joined: Jan 27, 2006 Posts: 95 Location: Spain
Audio files: 5
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Posted: Thu May 28, 2009 6:46 am Post subject:
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Probably you already did it but ... check T3 ( the trimmer near of the power connector ) , with this trimmer you adjust the shape of the sine wave ( from triangle to sine wave ) _________________ http://www.corsynth.com |
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Minimalist
Joined: Nov 21, 2008 Posts: 9 Location: NZ
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Posted: Thu May 28, 2009 12:09 pm Post subject:
LFO Sine wave shape problem |
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thanks Thalassa, yes I've tried varying the sine wave shape trimmer I'm getting the following variations , ie the top or bottom half of a sine wave but not the whole wave, any suggestions? I'm getting perfect triangle and saw waves.
Thanks Again
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Fri May 29, 2009 5:20 am Post subject:
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Hi seeing the oscillogram it is clear that the triangle wave has not the right amplitude. Check that the level of the triangle output is at 8Vpp (-4V/+4V).
If so then check thoroughly the value of the following components :
R26=150K, R27=22K
If the amplitude of the triangle is <<8Vpp then check R23=200K1%, _________________ Yves |
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Minimalist
Joined: Nov 21, 2008 Posts: 9 Location: NZ
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Posted: Wed Jun 03, 2009 12:40 am Post subject:
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Thanks Yves
wow you really know your stuff, the triangle was <<8Vpp so I checked all the recommended resistors, they were all correct so I just increased R23 to 300K which brought up the triangle to just over 8vpp which meant the sine wave now is good, thanks again for your patience with beginners questions.
Marcus |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Wed Jun 03, 2009 1:23 am Post subject:
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Minimalist wrote: | Thanks Yves
wow you really know your stuff, the triangle was <<8Vpp so I checked all the recommended resistors, they were all correct so I just increased R23 to 300K which brought up the triangle to just over 8vpp which meant the sine wave now is good, thanks again for your patience with beginners questions.
Marcus |
Great, however if the triangle was <<8pp then this mean that something was wrong with the sawtooth which must be at least 8Vpp. In the LFO, the core is a sawtooth wave anad all the other waveshapes are derived from it. This means that if the sawtooth has not the right amplitude then all the values of the wave-shaper resistors has to be adjusted.
Just as a matter of being sure and understand why you had to increase R23 to 300K can you check the values of R9,R1,R19,R20 and R21. ? _________________ Yves |
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