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talkboxert
Joined: Oct 08, 2008 Posts: 16 Location: Amsterdam, Netherlands
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Luka
Joined: Jun 29, 2007 Posts: 1003 Location: Melb.
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Posted: Fri Nov 28, 2008 12:33 am Post subject:
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it says 47n on the schematic so id go with that
lm394 is ok and pin 1 (should have a dot on this corner) should be in the top left corner according of each bc547 pair
check out the datasheet if you need any more info
just google lm394 datasheet
if you look at the bc547 you will notice the lm394 is just 2 transistors and you can match the collectors/emiiters up with the board pattern _________________ problemchild
melbourne australia
http://cycleofproblems.blogspot.com/
http://www.last.fm/user/prblmchild |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Fri Nov 28, 2008 1:49 am Post subject:
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Question 1:
both 22nF and 47nF are correct but I have found that I got a faithfuller minimoog sounding using 47nF, therefore I'd suggest that you go for the 47nF caps.
Question 2:
Yes the LM394 are there provided as substitute for the SSM2210 which are already substitue for the BC547s.
See below the layout diagram
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_________________ Yves |
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talkboxert
Joined: Oct 08, 2008 Posts: 16 Location: Amsterdam, Netherlands
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Posted: Fri Nov 28, 2008 1:04 pm Post subject:
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Can't be any clearer...... |
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talkboxert
Joined: Oct 08, 2008 Posts: 16 Location: Amsterdam, Netherlands
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Sat Nov 29, 2008 8:03 am Post subject:
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Hi
These are inductors (a wire wound around a ferrite bead), they are provided as substitutes for the two 10 ohm resistors (R1 R2), if you check on bridechamber's site you'll see it mentioned : Quote: | R1 and R2 are replaced with ferrite beads. |
Cheers
Yves _________________ Yves |
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talkboxert
Joined: Oct 08, 2008 Posts: 16 Location: Amsterdam, Netherlands
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Posted: Sat Nov 29, 2008 8:18 am Post subject:
thankx |
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thanks again! |
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LetterBeacon
Joined: Mar 18, 2008 Posts: 454 Location: London, UK
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Posted: Sat Nov 29, 2008 9:23 am Post subject:
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I'm hoping to build this soon, and so I'm just collecting the components together. You specify the 47nf caps to be matched to 1% - are these appropriate capacitors?
Also, on the wiring diagram it looks like the resistors all have 5% tolerance. Is that correct, or should I use ones with 1% tolerance?
Thanks a lot. |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Sat Nov 29, 2008 10:57 am Post subject:
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LetterBeacon wrote: | I'm hoping to build this soon, and so I'm just collecting the components together. You specify the 47nf caps to be matched to 1% - are these appropriate capacitors? |
These caps are OK. When I say 1%, this means that you take a batch of 47nF caps and you measure them with a capacimeter, then you select those within 1%. What counts is not the accuracy with respect to 47nF but rather the closeness between the values : they don't need to be 47nF exactly , but the four caps must have the same value within 1%, that is, it can be four caps with a value of 44nF fo example.
LetterBeacon wrote: | Also, on the wiring diagram it looks like the resistors all have 5% tolerance. Is that correct, or should I use ones with 1% tolerance?
Thanks a lot. |
5% is OK. _________________ Yves |
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LetterBeacon
Joined: Mar 18, 2008 Posts: 454 Location: London, UK
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Posted: Sat Nov 29, 2008 11:02 am Post subject:
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Great, thanks a lot! |
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talkboxert
Joined: Oct 08, 2008 Posts: 16 Location: Amsterdam, Netherlands
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Posted: Sun Nov 30, 2008 6:44 am Post subject:
Ferrite Beads |
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Quote: | R1 and R2 are replaced with ferrite beads. |
Just out of interest, why is this?
Also to make it sound more close to the original?
Cheers |
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Funky40
Joined: Sep 24, 2005 Posts: 875 Location: Swiss
Audio files: 1
G2 patch files: 5
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LetterBeacon
Joined: Mar 18, 2008 Posts: 454 Location: London, UK
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Posted: Sun Nov 30, 2008 9:43 am Post subject:
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Yves, just out of interest, what type of capacitor did you use in the circuit? I was going to use those polyester ones, but I've just read this:
Harry Bissell wrote: | For all frequency sensitive applications, film caps are the best choice. Polystyrene is the best, followed by polycarbonate, and polyester (Mylar). Mylar capacitors should always be avoided in Sample/Hold and VCO applications, and used with caution in VCF circuits. If the capacitance value is very small then mica or COG/NPO ceramics may be used. |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Sun Nov 30, 2008 10:19 am Post subject:
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I use polyester film capacitors for the filter. _________________ Yves |
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jbeuckm
Joined: Nov 30, 2008 Posts: 165 Location: Stockholm
Audio files: 9
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Posted: Sat Dec 13, 2008 1:19 am Post subject:
Self-oscillation Subject description: can't get it :( |
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I have a working model built but can't achieve self oscillation even with the emphasis trimmer and pot all the way up. I have to admit that I did not know to match the 47n capacitors to each other when I picked them. Could mismatched capacitors cause weak emphasis? What else would prevent self-oscillation?
Thank you,
-joe |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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Posted: Sat Dec 13, 2008 2:23 am Post subject:
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No, I think it should oscillate even with mismatched ladder caps.
OK check all the solders, swap or change the CA3046s. _________________ Yves |
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numbertalk
Joined: May 05, 2008 Posts: 992 Location: Austin, TX
Audio files: 5
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Posted: Sat Dec 13, 2008 7:49 am Post subject:
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What voltage power supply are you using? I first tried this with 2 9V batteries, before I had a bench or cabinet power supply, and I had the same problem. I think it really needs the 15V to oscillate. If you're using a 15VDC supply maybe it's a problem with one of the soldered connections to power on that chip. |
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jbeuckm
Joined: Nov 30, 2008 Posts: 165 Location: Stockholm
Audio files: 9
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Posted: Sat Dec 13, 2008 11:05 am Post subject:
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numbertalk wrote: | What voltage power supply are you using? |
That was it! I thought I was using my 15v rack but it was 12v. It oscillates nicely on +/-15v. Nice filter. Thanks for the help. |
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LetterBeacon
Joined: Mar 18, 2008 Posts: 454 Location: London, UK
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Posted: Sun Jan 11, 2009 10:17 am Post subject:
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I can't seem to find a source for the large 10K and 1K trim pots in the UK. Can anyone point me to where I can find these online?
Thanks! |
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yusynth
Joined: Nov 24, 2005 Posts: 1314 Location: France
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LetterBeacon
Joined: Mar 18, 2008 Posts: 454 Location: London, UK
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Posted: Sun Jan 11, 2009 10:42 am Post subject:
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Thanks for that. I went to Maplin yesterday and bought what I thought were the ones you linked to, but it turns out I bought the smaller ones instead. |
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furio
Joined: Dec 25, 2009 Posts: 117 Location: Austria
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Posted: Fri Nov 25, 2011 3:40 pm Post subject:
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Tomorrow I try my new filter
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