Super Regs - Page 3

iko · 20th September 2009, 02:12 PM

Quote:

Originally Posted by jackinnj

Almost a year later, here's the version I am going to work with -- mostly surface mount, save the rectifier diodes and electrolytic caps -- I have not had a lot of success mounting smt electrolytics. The reference for each is the LM4040:

Looks very nice Jack, I'm looking forward to some results from you. I've looked into using a high performance opamp buffer in a different regulator as well, but then dropped the idea. Is the lm4040 a reasonably low noise reference in reality? I have no experience with it.

jackinnj · 20th September 2009, 06:09 PM

Quote:

Originally Posted by ikoflexer

Is the lm4040 a reasonably low noise reference in reality? I have no experience with it.

The LM329 is quieter, but not available in SOT-23

peranders · 20th September 2009, 07:08 PM

LM329 is one of the best and it's a mystery why you can't find any similar in SMD package.

jackinnj · 20th September 2009, 07:27 PM

I wanted to use what I had on hand -- and the one reference I had in SOT-23 was the LM4040 which, by coincidence, Nat Semi used as well. I also used through-hole rectifiers!

Will see how we do when the stuff comes back. I have stock Super Regulator boards from Old Colony to compare noise, impedance etc.

peranders · 25th September 2009, 09:47 AM

Quote:

Originally Posted by janneman

You read my mind or what

?

I just read a comment by Scott Wurcer, the designer of the 797, here:

http://www.diyaudio.com/forums/showt...64#post1509264

Wish I had know that at the time...

Jan Didden

It would be interesting to see what this little cap could do practically. It was a long time since I tested AD797.

jackinnj · 30th September 2009, 01:52 AM

Well, the first try ran over a cliff and died -- I got one version to work right for a few seconds -- then it oscillated itself to death.

iko · 30th September 2009, 02:06 AM

Jack, is this your new reg? I meant to ask how it was coming along.

jackinnj · 30th September 2009, 12:28 PM

Quote:

Originally Posted by ikoflexer

Jack, is this your new reg? I meant to ask how it was coming along.

It's the design from the LME49600 datasheet, nothing original there. The open loop bandwidth of the LMe49600 is 110MHz (180MHz if the bandwidth pin is brought to Vee).

I strongly suspect that it is a layout issue, since all of the connections are correct per the schematic. I did have a layout issue with the SOT-23 LM4040 which I fixed.

iko · 30th September 2009, 02:23 PM

Did you use an output cap at all? There's also Jimmie D. Felps' trick with the small resistor in series with the output, for stopping crazy opamps oscillation (applies only to driving capacitive loads, but worth trying because it's so easy).

peranders · 30th September 2009, 02:31 PM

Jack, when I see your grounding scheme, how did you think? You have made a dual PS with two separate ground connections? Grounding is critical you know.

20th September 2009, 07:08 PM	#23
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	LM329 is one of the best and it's a mystery why you can't find any similar in SMD package. __________________ /Per-Anders (my first name) or P-A as my friends call me Tube Buffered Gainclone in work \|Thread

30th September 2009, 02:31 PM	#30
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	Jack, when I see your grounding scheme, how did you think? You have made a dual PS with two separate ground connections? Grounding is critical you know. __________________ /Per-Anders (my first name) or P-A as my friends call me Tube Buffered Gainclone in work \|Thread

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20th September 2009, 07:27 PM	#24
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	I wanted to use what I had on hand -- and the one reference I had in SOT-23 was the LM4040 which, by coincidence, Nat Semi used as well. I also used through-hole rectifiers! Will see how we do when the stuff comes back. I have stock Super Regulator boards from Old Colony to compare noise, impedance etc.

30th September 2009, 01:52 AM	#26
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	Well, the first try ran over a cliff and died -- I got one version to work right for a few seconds -- then it oscillated itself to death.

30th September 2009, 02:06 AM	#27
iko diyAudio Moderator Join Date: May 2008 Location: Toronto	Jack, is this your new reg? I meant to ask how it was coming along.

30th September 2009, 02:23 PM	#29
iko diyAudio Moderator Join Date: May 2008 Location: Toronto	Did you use an output cap at all? There's also Jimmie D. Felps' trick with the small resistor in series with the output, for stopping crazy opamps oscillation (applies only to driving capacitive loads, but worth trying because it's so easy).