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toppobrillo
Joined: Dec 10, 2005 Posts: 766 Location: oakland, ca
G2 patch files: 1
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Posted: Tue Feb 08, 2011 3:45 am Post subject:
dual 281 project [build related stuff only!] |
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post build related questions/ comments here, no order related stuff. use the main thread for those.
assembly PDF is up, new BOM to follow:
http://www.sdiy.org/toppobrillo/DOWNLOADS/2812_DUAL/ |
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ericcoleridge
Joined: Jan 16, 2007 Posts: 889 Location: NYC
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Posted: Tue Feb 08, 2011 12:08 pm Post subject:
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Fantastic! Thanks Topp! This looks WAY easier to assemble than was the single circuit config. Man, that was a headache : ) |
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J3RK
Joined: Jun 05, 2006 Posts: 123 Location: Seattle
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Posted: Wed Feb 09, 2011 2:57 pm Post subject:
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Is there any reason I shouldn't use 4066s in place of 4016s? (I happen to have a ton of 66s that I never used) From what I can tell it should be fine. Haven't consulted the datasheets yet, but will be. |
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toppobrillo
Joined: Dec 10, 2005 Posts: 766 Location: oakland, ca
G2 patch files: 1
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Posted: Wed Feb 09, 2011 3:01 pm Post subject:
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Quote: | Is there any reason I shouldn't use 4066s in place of 4016s? |
afaik no should be fine. |
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J3RK
Joined: Jun 05, 2006 Posts: 123 Location: Seattle
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Posted: Wed Feb 09, 2011 3:29 pm Post subject:
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topp wrote: | Quote: | Is there any reason I shouldn't use 4066s in place of 4016s? |
afaik no should be fine. |
Cool. I just looked at the datasheets, and as I read previously they are just improved (noise, impedance, etc.) It looks like each switch has a few extra components in the 4066, but otherwise similar. Think I'll use them. |
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emdot_ambient
Joined: Nov 22, 2009 Posts: 667 Location: Frederick, MD
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J3RK
Joined: Jun 05, 2006 Posts: 123 Location: Seattle
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Posted: Mon Feb 14, 2011 11:48 am Post subject:
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I should have my parts today or tomorrow, and will get started on the build. The only thing I didn't grab was a 7810. Will have to run out, and grab one.
Quick question on the 062s. I was going to use 072s in their place, (because I have about a billion of them,) but thought I'd see if there was a specific reason the 062s were used. From what I understand, the 062s are just a bit better with low current/voltage situations, but maybe I'm missing something?
That aside, I think I'll be building tomorrow night. |
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gddfp
Joined: Jan 11, 2009 Posts: 21 Location: Belgium
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Posted: Thu Feb 17, 2011 5:44 am Post subject:
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I assume the pots for Attack & Decay are LOG (in the original) ? |
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toppobrillo
Joined: Dec 10, 2005 Posts: 766 Location: oakland, ca
G2 patch files: 1
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Posted: Thu Feb 17, 2011 4:46 pm Post subject:
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Quote: | Quick question on the 062s. I was going to use 072s in their place, (because I have about a billion of them,) but thought I'd see if there was a specific reason the 062s were used. From what I understand, the 062s are just a bit better with low current/voltage situations, but maybe I'm missing something? |
TL06_ are low power opamps, they use like 1/10th the current of the 07_s. they are also around 4x slower. so for this application they're great economy. i haven't measured the current draw of the new dual board, but I would reckon its around 25-30mA orso with the 62s in. if you used 72s/71 you're looking at something significantly higher, maybe 50mA, just guessing, with no advantage other than that you already have the chips you might see the FGs easily soft-syncing in cycle mode with the higher current demand spikes. anyways, I say use sockets, try it and see.
Quote: |
I assume the pots for Attack & Decay are LOG (in the original) ? |
they would be linear. |
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J3RK
Joined: Jun 05, 2006 Posts: 123 Location: Seattle
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Posted: Thu Feb 17, 2011 5:52 pm Post subject:
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Thanks Topp!
That's more or less what I was thinking. I'll socket them and swap. I'm running a fairly large power supply, so the overall current draw shouldn't be an issue. (especially with the small size of my overall system.) The spikes could still be an issue though. I'll give both a try. I don't see any reason not to order a tube of 062s. |
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toppobrillo
Joined: Dec 10, 2005 Posts: 766 Location: oakland, ca
G2 patch files: 1
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Posted: Thu Feb 17, 2011 7:15 pm Post subject:
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Quote: | I don't see any reason not to order a tube of 062s |
I use them alot |
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waveselector
Joined: Nov 17, 2008 Posts: 14 Location: chicago
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Posted: Thu Feb 17, 2011 8:22 pm Post subject:
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on the solder side of the PCB there appear to be pads for some SMD components - can you shed some light on those, topp? _________________ concerned with insignificances |
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toppobrillo
Joined: Dec 10, 2005 Posts: 766 Location: oakland, ca
G2 patch files: 1
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Posted: Thu Feb 17, 2011 8:58 pm Post subject:
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Quote: | on the solder side of the PCB there appear to be pads for some SMD components - can you shed some light on those, topp? |
bypass caps, .1uF 0805 sized |
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waveselector
Joined: Nov 17, 2008 Posts: 14 Location: chicago
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Posted: Thu Feb 17, 2011 9:04 pm Post subject:
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doh! i knew i was too hasty when i made that mouser order...
maybe i'll just slap some ceramic disc ones on... sloppy, but it's what i've got! |
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toppobrillo
Joined: Dec 10, 2005 Posts: 766 Location: oakland, ca
G2 patch files: 1
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Posted: Thu Feb 17, 2011 9:28 pm Post subject:
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yeah ive done that too no biggie.. or you could just leave them off for now, i doubt you'd notice a difference. |
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gddfp
Joined: Jan 11, 2009 Posts: 21 Location: Belgium
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Posted: Thu Feb 17, 2011 10:49 pm Post subject:
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gddfp wrote: | I assume the pots for Attack & Decay are LOG (in the original) ? |
topp wrote: | they would be linear. |
Have a look at the original Buchla panel. The scaling marks around those knobs do not look very linear...
And that makes sense to me. It's far more important to be able to finely adjust the faster rates than the slower rates. |
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toppobrillo
Joined: Dec 10, 2005 Posts: 766 Location: oakland, ca
G2 patch files: 1
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Posted: Fri Feb 18, 2011 1:47 am Post subject:
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Quote: | Have a look at the original Buchla panel. The scaling marks around those knobs do not look very linear...
And that makes sense to me. It's far more important to be able to finely adjust the faster rates than the slower rates. |
have a look at the schematic.
from my diy page:
The output function is linear, however, the rate [slope] responds to applied control voltage in an exponential manner. Applied positive voltages will cause the generator to ramp more slowly- while voltages that are less positive than the voltage at the control pot's wiper will cause the generator to ramp more quickly. These voltages average together.
if you used a log pot, you would linearize the time vs. knob rotation relationship. |
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gddfp
Joined: Jan 11, 2009 Posts: 21 Location: Belgium
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Posted: Fri Feb 18, 2011 1:54 am Post subject:
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gddfp wrote: | Have a look at the original Buchla panel. The scaling marks around those knobs do not look very linear... |
topp wrote: | if you used a log pot, you would linearize the time vs. knob rotation relationship. |
Okay, that makes sense.
All clear now.
Thanks, Topp. |
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negativspace
Joined: Dec 25, 2010 Posts: 17 Location: Manhattan, Kansas
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Posted: Sun Feb 20, 2011 11:19 am Post subject:
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Are the two circle-marked parts near the 3904s trimpots? If so, are they 25-50k as specified in your previous versions?
Thanks! |
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toppobrillo
Joined: Dec 10, 2005 Posts: 766 Location: oakland, ca
G2 patch files: 1
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Posted: Sun Feb 20, 2011 4:39 pm Post subject:
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Quote: | Are the two circle-marked parts near the 3904s trimpots? If so, are they 25-50k as specified in your previous versions?
Thanks! |
yep |
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mph
Joined: Aug 25, 2007 Posts: 87 Location: France
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Posted: Wed Mar 09, 2011 4:56 pm Post subject:
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What kind of trimmers do you use please?
And is there a need to match the 3906s?
Thanks a lot. |
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toppobrillo
Joined: Dec 10, 2005 Posts: 766 Location: oakland, ca
G2 patch files: 1
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Posted: Wed Mar 09, 2011 9:51 pm Post subject:
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Quote: | What kind of trimmers do you use please?
And is there a need to match the 3906s?
Thanks a lot. |
hi- 2.5mm or 5mm lead spacing will work here, 20-50K or so.
the xistrs- no need to.. |
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mph
Joined: Aug 25, 2007 Posts: 87 Location: France
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Posted: Wed Mar 16, 2011 6:45 am Post subject:
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Hello Topp
thanks for your reply, I've found some Bourns trimmer which seem to fit the pcb.
I've one more question; what are the componments labelled "L+" and "L-"?
Are they ferrite beads, or 10ohm resistors?
And please, do you have a current BOM for this version, or should I use the older one?
Cheers |
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e-grad
Joined: Sep 12, 2008 Posts: 142 Location: Berlin
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Posted: Thu Mar 17, 2011 3:24 am Post subject:
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mph wrote: | what are the componments labelled "L+" and "L-"?
Are they ferrite beads, or 10ohm resistors? |
I prefer beads but you can use 10 ohm or 22 ohm resistors as well.
Basically even a link will work. |
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mph
Joined: Aug 25, 2007 Posts: 87 Location: France
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Posted: Thu Mar 17, 2011 7:40 am Post subject:
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thanks e-grad
I've made a new BOM for this version, based on the V3 but including the changes with the 3080 and the 13700...
If someone need it I could post here. |
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