| Author |
Message |
toppobrillo
Joined: Dec 10, 2005
Posts: 766
Location: oakland, ca
G2 patch files: 1
|
 Posted: Fri Apr 11, 2008 5:04 pm Post subject:
|
  |
|
| Quote: | | Emulator Archive also offer a EMU VC Lag PCB |
| Quote: | | I believe that I have the EMU lag pcb artwork in my flickr account |
there exist 2 versions of this circuit- the EA clone is of the revision. no OTAs! |
|
|
Back to top
|
|
 |
CJ Miller
Joined: Jan 07, 2007
Posts: 368
Location: 127.0.0.1
|
| Posted: Sat May 03, 2008 6:05 am Post subject:
|
|
|
Hi all. I was just looking for my handfull of LM3900s... I know I have at least three of them here. I have never bought any but I should. Serge also used MC3401. I don't know how the LM2900 would do.
I have never seen or played with a Serge, but have always been fascinated with the versatile functions and processing. Can anyone tell me what the difference is between the positive/negative slews, and the DSG? All I have read is that the DSG is like those two together "with extra stuff". |
|
|
Back to top
|
|
|
andrewF
Joined: Dec 29, 2006
Posts: 1176
Location: australia
Audio files: 4
|
| Posted: Sat May 03, 2008 8:01 am Post subject:
|
|
|
| CJ Miller wrote: | Hi all. I was just looking for my handfull of LM3900s... I know I have at least three of them here. I have never bought any but I should. Serge also used MC3401. I don't know how the LM2900 would do.
|
I think there isn't much difference between these chips, other than the 3401 has max VCC of 18V, the others can handle 32V.
Like you I have never actually seen a Serge, but as mentioned in this thread you can build the neg slew - it is an easy build and worth it. you don't have to use a 3086, 5 npn trannies will do. |
|
|
Back to top
|
|
|
otherunicorn
Joined: May 11, 2008
Posts: 136
Location: Australia
|
| Posted: Tue May 27, 2008 2:37 am Post subject:
|
|
|
| CJ Miller wrote: | Hi all. I was just looking for my handfull of LM3900s... I know I have at least three of them here. I have never bought any but I should. Serge also used MC3401. I don't know how the LM2900 would do.
I have never seen or played with a Serge, but have always been fascinated with the versatile functions and processing. Can anyone tell me what the difference is between the positive/negative slews, and the DSG? All I have read is that the DSG is like those two together "with extra stuff". |
LM2900 is a better speced version of the LM3900. There will be no problems using them instead of LM3900 or MC3401. I expect the only reason the latter were used is price.
If I recall correctly, A Positive slew works only on upwards going signals. A Negative slew works only on downward going signals. Their circuitry is quite different from each other. It's been a while since I played with mine because my VCO panel is still upside down on the bench 
_________________
http://www.cgs.synth.net/ |
|
|
Back to top
|
|
|
CJ Miller
Joined: Jan 07, 2007
Posts: 368
Location: 127.0.0.1
|
| Posted: Tue May 27, 2008 7:12 am Post subject:
|
|
|
Hi Ken!
Yes, since then I've looked over some datasheets to see what the differences are. The MC3401 has a limited voltage range, and the LM2900 is the industrial spec 3900 with wider temperature range. I lucked out because at Unicorn Electronics (!) LM3900 are $0.59 each, but the LM2900 are $0.20 each! Cheapest Norton amps I've ever seen, so I stocked up.
I was looking at the boards for the slew circuits on your site, I was just noticing myself how different they are. I wonder if a few 3046 arrays might work where that field of NPNs is. It's a lack of discipline, I suppose, but I started feeling dizzy after about 40 minutes of tracing things on the positive slew. I am certainly not going to copy their layout on perfboard! If I meditate on it for a while I might see where things go.
I've heard that the DSG is like a negative and positive slope together - but different. Any ideas about how a DSG resembles/differs from combining a positive and negative slew circuit in the same module? These old Serge circuits are making me really curious! I'm going to put a small system together to try breadboarding these with. |
|
|
Back to top
|
|
|
GlassX
Joined: Jan 27, 2008
Posts: 50
Location: Brazil
|
| Posted: Thu May 29, 2008 9:29 pm Post subject:
|
|
|
| CJ Miller wrote: | | I've heard that the DSG is like a negative and positive slope together - but different. Any ideas about how a DSG resembles/differs from combining a positive and negative slew circuit in the same module? These old Serge circuits are making me really curious! I'm going to put a small system together to try breadboarding these with. |
I don't think these old modules have something to do with the Dual Slope Generator...
I believe that the DSG is simply an AD/AR Envelope Generator with the diodes/pots replaced with something like the four transistors on the Envylope.
However, there's a "signal input" that allows VC Lag. This input simply skips the logic gates/schmitt triggers, and is connected right before the Rise/Fall circuit.
By the way, I can get similar functionality (minus the VC rise/fall control - but I could use vactrols!) with my own envelope generator circuit. |
|
|
Back to top
|
|
|
CJ Miller
Joined: Jan 07, 2007
Posts: 368
Location: 127.0.0.1
|
| Posted: Sat May 31, 2008 6:52 am Post subject:
|
|
|
Hi GlassX. From what I have read, the DSG is more than a VC AD/AR. This sounds more like the Serge DTG to me. The DSG sounds like a much more general-purpose function generator. That doesn't have a VC slew added on, but that this is part of the same circuitry which also acts like EGs, LFOs, filters, envelope followers, etc, etc. But, this having been said, is based on my reading, not upon actual use or examination of an actual Serge DSG. It just sounds as if it is elegant and, to me, mind-bogglingly useful.
And yes, Envylope also looks like another very cool project. |
|
|
Back to top
|
|
|
GlassX
Joined: Jan 27, 2008
Posts: 50
Location: Brazil
|
| Posted: Sat May 31, 2008 9:08 am Post subject:
|
|
|
| CJ Miller wrote: | | Hi GlassX. From what I have read, the DSG is more than a VC AD/AR. This sounds more like the Serge DTG to me. The DSG sounds like a much more general-purpose function generator. That doesn't have a VC slew added on, but that this is part of the same circuitry which also acts like EGs, LFOs, filters, envelope followers, etc, etc. But, this having been said, is based on my reading, not upon actual use or examination of an actual Serge DSG. It just sounds as if it is elegant and, to me, mind-bogglingly useful. |
Actually, the difference between the Dual Transient Generator and the Dual Slope Generator is the 1V/Oct and the direct Signal Input. And I can get all the functions you described with my circuit, even Filtering and Envelope Following. It's just a matter of feeding the Input into the integrator.
I just don't have voltage controlled 1/VOct rise/fall times, but that would be easy. |
|
|
Back to top
|
|
|
PrimateSynthesis
Joined: May 02, 2008
Posts: 69
Location: U.S.A.
|
| Posted: Fri Mar 06, 2009 1:02 pm Post subject:
|
|
|
That link seems dead. Could you please post it here or know where else I could find it?
Also, you might want to check out the LM3900 application notes. It has a number of circuits that could be used in a synth.
Thanks  |
|
|
Back to top
|
|
|
Junk Rhythm
Joined: Jan 07, 2008
Posts: 81
Location: San Francisco, CA
|
|
|
Back to top
|
|
|
Luka
Joined: Jun 29, 2007
Posts: 1003
Location: Melb.
|
|
|
Back to top
|
|
|
PrimateSynthesis
Joined: May 02, 2008
Posts: 69
Location: U.S.A.
|
| Posted: Sat Mar 07, 2009 6:33 am Post subject:
|
|
|
Thanks
I had never even heard of Bergfrotron. I looked there and there seems to be a dead link to JH's design. Anyway, I found this:
http://m.bareille.free.fr/modular1/adsr/mb_cvadsr2.htm
Which seems to be based on the same cote. He also has PCB's for sale. |
|
|
Back to top
|
|
|
|
Forum index » DIY Hardware and Software
FAQ
Calendar
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
Chat Room
