Super Regulator, collecting the facts - Page 57

janneman · 24th November 2009, 01:20 PM

Quote:

Originally Posted by ikoflexer

Interesting. Shielding against RFI/EMI?

My look was mostly to hum and capacitive feedback.

jd

peranders · 01:32 PM

The pcb has ground planes on all four layers where two of them are only ground, no traces and I have also add a cap between output of the opamp and the - input, just in case. I haven't had any opportunity to harass the pcb with RF.

The LM317 has decoupled feedback but the gain is only two so the impact of this cap will be minor I should think.

janneman · 24th November 2009, 01:58 PM

Quote:

Originally Posted by peranders

The pcb has ground planes on all four layers where two of them are only ground, no traces and I have also add a cap between output of the opamp and the - input, just in case. I haven't had any opportunity to harass the pcb with RF.

The LM317 has decoupled feedback but the gain is only two so the impact of this cap will be minor I should think.

I must publicly apologize here to P-A. He send me a board of his reg to evaluate but I still haven't found the time to do it. I did note the excellent pcb he developed.
P-A, if you want me to send the board back or to another 'tester' let me know.

jd

peranders · 02:28 PM

No problem with the pcb since you are I think entitled to a reference pcb

and I would be pleased if you would test it but feel no pressure.

jackinnj · 25th November 2009, 03:25 AM

LME49720 is very good. Indeed, it is very, very good, but not quite "superb" as compared to AD797 or LT1028 in simple comparison of noise in the Super Reg. HOWEVER, at most of the US distributors this chip is about 1/2 the price of the AD797 and LT1028.

Pano · 27th November 2009, 11:36 PM

That's good to know. Thanks.
The lower cost is one reason I choose the LME49720. But even it was out of stock at the time I was building.
So I ended up with the OPA1611 as a place holder. It seems to be happy in the circuit.
Wonder how much better one of the "superb" opamps would be?

peranders · 26th March 2010, 02:36 PM

Mr jackinnj has once again done some noise measurements and my pcb behaves quite nicely although the difference is small.

The Invisus regulator is a 185 dollar product.

Noise is only one parameter. It would have been fun to know the output impedance as a function of the frequency.

ikoflexer · 26th March 2010, 03:39 PM

Nice results! Considering that at 1kHz the difference in noise between the best and the worst seems 200nV, the real practical difference MIGHT be in the output impedance. As noon as you wiggle the load there'll be a lot more than microvolts ripple at the output. It would be nice to see, at least Zout at a few frequencies, 100, 500, 1k, 3k, 10k, 15k?

peranders · 6th April 2010, 03:54 PM

It would have been nice to see the output impedance figures. I'll hope that Mr. Man in New York finds the time to do those measurements.

jackinnj · 6th April 2010, 04:04 PM

It isn't easy or trivial to measure micro-Ohms!

24th November 2009, 01:30 PM	#562
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	The pcb has ground planes on all four layers where two of them are only ground, no traces and I have also add a cap between output of the opamp and the - input, just in case. I haven't had any opportunity to harass the pcb with RF. The LM317 has decoupled feedback but the gain is only two so the impact of this cap will be minor I should think. __________________ /Per-Anders (my first name) or P-A as my friends call me Last edited by peranders; 24th November 2009 at 01:32 PM.

24th November 2009, 02:25 PM	#564
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	No problem with the pcb since you are I think entitled to a reference pcb and I would be pleased if you would test it but feel no pressure. __________________ /Per-Anders (my first name) or P-A as my friends call me Last edited by peranders; 24th November 2009 at 02:28 PM.

6th April 2010, 03:54 PM	#569
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	It would have been nice to see the output impedance figures. I'll hope that Mr. Man in New York finds the time to do those measurements. __________________ /Per-Anders (my first name) or P-A as my friends call me

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25th November 2009, 03:25 AM	#565
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	LME49720 is very good. Indeed, it is very, very good, but not quite "superb" as compared to AD797 or LT1028 in simple comparison of noise in the Super Reg. HOWEVER, at most of the US distributors this chip is about 1/2 the price of the AD797 and LT1028.

27th November 2009, 11:36 PM	#566
Pano diyAudio Moderator Join Date: Oct 2004 Location: North Carolina Blog Entries: 4	That's good to know. Thanks. The lower cost is one reason I choose the LME49720. But even it was out of stock at the time I was building. So I ended up with the OPA1611 as a place holder. It seems to be happy in the circuit. Wonder how much better one of the "superb" opamps would be?

26th March 2010, 03:39 PM	#568
ikoflexer diyAudio Moderator Join Date: May 2008 Location: Toronto	Nice results! Considering that at 1kHz the difference in noise between the best and the worst seems 200nV, the real practical difference MIGHT be in the output impedance. As noon as you wiggle the load there'll be a lot more than microvolts ripple at the output. It would be nice to see, at least Zout at a few frequencies, 100, 500, 1k, 3k, 10k, 15k?

6th April 2010, 04:04 PM	#570
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	It isn't easy or trivial to measure micro-Ohms!

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