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PHOBoS
Joined: Jan 14, 2010 Posts: 5591 Location: Moon Base
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tokyomatik
Joined: Jan 20, 2011 Posts: 171 Location: berlin
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Posted: Tue Apr 14, 2015 9:33 am Post subject:
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i'm trying with a 12v psu at the moment and from the 2262 when i turn the freq pot i get a voltage variable between 11.58v and 7v....
is that ok?
where should i look now?? |
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breadman
Joined: Apr 21, 2015 Posts: 1 Location: New York
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Posted: Tue Apr 21, 2015 7:52 am Post subject:
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I'm having pretty much the same issue as tokyomatik-- fine unfiltered sound, no filtered sound. I've only tried it with this fresh 9v which is actually supplying 9.58v, but right now pin 7 on the 2262 is reading between about 6.2v and 9.4 as I turn the freq pot. I've got the scope fired up, but would love to know if anyone has any ideas! |
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tokyomatik
Joined: Jan 20, 2011 Posts: 171 Location: berlin
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Posted: Sun Apr 26, 2015 3:06 am Post subject:
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still mumbling about the reason why the filter is not working....
did u solved it?
any ideas? |
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PHOBoS
Joined: Jan 14, 2010 Posts: 5591 Location: Moon Base
Audio files: 705
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Posted: Sun Apr 26, 2015 4:03 am Post subject:
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tokyomatik wrote: | i'm trying with a 12v psu at the moment and from the 2262 when i turn the freq pot i get a voltage variable between 11.58v and 7v....
is that ok?
where should i look now?? |
That sounds ok to me.
breadman wrote: | I'm having pretty much the same issue as tokyomatik-- fine unfiltered sound, no filtered sound. I've only tried it with this fresh 9v which is actually supplying 9.58v, but right now pin 7 on the 2262 is reading between about 6.2v and 9.4 as I turn the freq pot. I've got the scope fired up, but would love to know if anyone has any ideas! |
hmm interesting that you seem to have the same problem. Just to make sure do you get any sound out of it when the mixpot
is turned to the filter (so just unfiltered sound) or no sound at all ?
the voltage on pin 7 tells me that the CV control part is ok (or at least it does something), so the current control
for the OTAs works. If you get any sound out than the signal also flows through the OTAs. So I'm not sure why it
wouldn't be working.
maybe if you (both) take some clear photos I can spot something. _________________ "My perf, it's full of holes!"
http://phobos.000space.com/
SoundCloud BandCamp MixCloud Stickney Synthyards Captain Collider Twitch YouTube |
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tokyomatik
Joined: Jan 20, 2011 Posts: 171 Location: berlin
Audio files: 6
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Posted: Sun Apr 26, 2015 6:58 am Post subject:
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actually the mix pot pass the sound but unfiltered, with pot completely close i have no sound at all
i could try to take picture of the board later if i find the battery for the camera |
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PHOBoS
Joined: Jan 14, 2010 Posts: 5591 Location: Moon Base
Audio files: 705
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Posted: Tue May 05, 2015 9:25 am Post subject:
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oh dear I clicked the wrong button, sorry
anyway your reply was tokyomatik wrote: | i found the battery, later some photos
could be that i used lm741 instead of ua741(this board doesn't look design for tle246)....?? |
That shouldn't matter. Actually any single opamp would probably work, it just creates a fake ground at half the supply
voltage which is the same thing as the TLE2426 is used for. You could measure the output voltage (pin 6) to see if it
works but since the CV section seems to be working it should be ok. Do you have a scope ? _________________ "My perf, it's full of holes!"
http://phobos.000space.com/
SoundCloud BandCamp MixCloud Stickney Synthyards Captain Collider Twitch YouTube |
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tokyomatik
Joined: Jan 20, 2011 Posts: 171 Location: berlin
Audio files: 6
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Posted: Tue May 05, 2015 10:10 am Post subject:
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yep i have a scope |
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tokyomatik
Joined: Jan 20, 2011 Posts: 171 Location: berlin
Audio files: 6
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Posted: Tue May 05, 2015 11:04 am Post subject:
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i checked pin 6 and i have 4.46v.... i should have 0v... ? |
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PHOBoS
Joined: Jan 14, 2010 Posts: 5591 Location: Moon Base
Audio files: 705
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Posted: Tue May 05, 2015 11:38 am Post subject:
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no, ignore the label 0V in the schematic. It's a bit confusing since it would be 0V with a real dual supply,
but in this case it's a fake ground at half the supply voltage so with a 9V supply 4.46V is a good value.
I have to do some tests with a scope myself to see what's useful. It might be a bit tricky since the levels
are very much attenuated throughout the circuit and boosted later on in the mixer section. But you should probably
be able to see the input signal on pins 8 and 9 (if it's working that is). Best would be to test with a noise source
although some music will probably work too as long as you have something with a wide frequency range. _________________ "My perf, it's full of holes!"
http://phobos.000space.com/
SoundCloud BandCamp MixCloud Stickney Synthyards Captain Collider Twitch YouTube |
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tokyomatik
Joined: Jan 20, 2011 Posts: 171 Location: berlin
Audio files: 6
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Posted: Tue May 05, 2015 12:15 pm Post subject:
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funny...for the test i'm using exactly a noise source.... |
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tokyomatik
Joined: Jan 20, 2011 Posts: 171 Location: berlin
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PHOBoS
Joined: Jan 14, 2010 Posts: 5591 Location: Moon Base
Audio files: 705
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Posted: Mon Jun 01, 2015 4:22 am Post subject:
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tokyomatik wrote: | should i take a picture of the copper side too?? |
yes please, and maybe a photo that shows how the pots are wired although I don't really doubt you did that correct.
(but have to rule everything out) the resolution is great!
I will take a look at it this evening and maybe do another test with my scope. Last one wasn't very succesful because
the levels are very low and there is a large DC offset voltage throughout the circuit. So I couldn't really get it into view
on my (old) scope and the AC setting seemed to screw it up. What's the level of your noise source ?, so I can use a similar
level. _________________ "My perf, it's full of holes!"
http://phobos.000space.com/
SoundCloud BandCamp MixCloud Stickney Synthyards Captain Collider Twitch YouTube Last edited by PHOBoS on Mon Jun 01, 2015 8:43 am; edited 1 time in total |
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tokyomatik
Joined: Jan 20, 2011 Posts: 171 Location: berlin
Audio files: 6
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Posted: Mon Jun 01, 2015 4:33 am Post subject:
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later i will take another picture of the copper side
as noise source i use the white noise of my ms20 and the noise source of my sn76477 voice, so if i'm not wrong should be -+5v for the ms20 |
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PHOBoS
Joined: Jan 14, 2010 Posts: 5591 Location: Moon Base
Audio files: 705
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Posted: Mon Jun 01, 2015 4:32 pm Post subject:
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I'm not 100% sure but it looks like you used a 4K7 resistor instead of 47K for R5. It's attached to pin4 of the LM13700
and on your photo it's in the top left corner between the 1nF and 22pF capacitor. Brown and red look a bit alike
though so measure it to be sure. The rest of the components are correct from what I can tell. _________________ "My perf, it's full of holes!"
http://phobos.000space.com/
SoundCloud BandCamp MixCloud Stickney Synthyards Captain Collider Twitch YouTube |
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tokyomatik
Joined: Jan 20, 2011 Posts: 171 Location: berlin
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PHOBoS
Joined: Jan 14, 2010 Posts: 5591 Location: Moon Base
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tokyomatik
Joined: Jan 20, 2011 Posts: 171 Location: berlin
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Posted: Wed Jun 03, 2015 4:40 pm Post subject:
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So....what do u mean with watching from the backside? back or front pin 1 is pin 1, pin 2 is pin 2 and so on...this is to say that also the pots are ok?
now the only option left is to take a picture of the copper side
but my camera is dead and i have to ask to a friend( the one that took also the other picture)
and when also that is correct...well..... then i will give up this filter and move on
to the acoustic side of music and maybe gardening |
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PHOBoS
Joined: Jan 14, 2010 Posts: 5591 Location: Moon Base
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Paradigm X
Joined: Feb 15, 2011 Posts: 363 Location: Null and void
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Posted: Tue Aug 04, 2015 2:05 am Post subject:
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Hey
This filter looks very interesting. Does anyone know if its possible to extract a high pass response as well?
Cheers |
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PHOBoS
Joined: Jan 14, 2010 Posts: 5591 Location: Moon Base
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Paradigm X
Joined: Feb 15, 2011 Posts: 363 Location: Null and void
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Posted: Thu Aug 06, 2015 3:09 am Post subject:
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Interesting, many thanks. I forgot you could fudge a HPF like like.
Im deciding between this and the WASP filter. This is simpler, but the wasp does everything i want, including distortion.
Cheers for the reply.
Ben |
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