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Old 6th October 2009, 08:08 PM   #41
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Quote:
Originally Posted by ikoflexer View Post
Oh, then unless you used the same reference device for each of them I'm afraid we're comparing apples with oranges. No?
Well, the 78L15 and the LM317 have their own internal references, the reference for the LME49600 regulator is the LM4040 and the WJ Regulator uses an LM329DZ. All the regulators were powered by the same battery setup, and all used the same load configuration.
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Old 6th October 2009, 11:06 PM   #42
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I note, for the record, that the measurement cited for the Super-Reg was with an LT1028 from Linear, not an AD797 or AD825.

For jollies, I measured the noise (again A-weighted) with the SMT version of WJ's Super Reg -- same load and connection to the AP Analyzer -- it measures 602nV noise RMS and 968nV Quasi Peak. That's nano-s.

This uses the SMT versions of the transistors discussed in the article, and the MJD series transistors which are D-Pak versions of the TO-220 used in the 1995 article, and one and only one LM329DZ as reference.
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Old 7th October 2009, 01:54 AM   #43
iko is offline iko  Canada
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You can measure nanoV? Wow! Nice results. How's the output impedance of the smt one?
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Old 7th October 2009, 02:08 AM   #44
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Quote:
Originally Posted by ikoflexer View Post
You can measure nanoV? Wow! Nice results. How's the output impedance of the smt one?
The AP Measures nV -- but I want to repeat the results -- here in NJ there is so much environmental electronic pollution it is just unbelievable -- so when I measure all the regs at the same time during the day. It means that I have to set up all the regulators at the same time and solder them into the test jig, let them cool off etc., etc.

The preamplifier I have when I use the HP3581 has a noise floor in the low nano-Volts -- it is basically Dennis Colin's from AudioXpress without the filters.
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Old 7th October 2009, 02:08 AM   #45
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Quote:
Originally Posted by jackinnj View Post
Well, forget about the LME49600 Regulator -- here are some results --

A Weighted level measurements -- a.c. coupled with 15mA load -- shielded by my Oreo Cookie Tin:

78L15 (ST Micro) RMS 26.9uV, Quasi-Peak 44.3uV
LM317 (National, No adj bypass) RMS 181uV, Q-Peak 289uV
Super-Regulator (LT1028 error amp) RMS 2.2uV, Q-Peak 3.6uV

LME49600 (LM4040 Ref) RMS 347uV, Q-Peak 564uV

My advice to you, young man, get the Super-Reg boards from Old Colony and stop wasting your time.

The Super Reg is only slightly noisier than the battery.

Excellent work
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Old 7th October 2009, 01:36 PM   #46
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I want to take the numbers in post 42 back -- I can't replicate them this morning for the SMT version -- it is coming up a little worse than the LT1028 super-reg on the Old Colony Board and I can't figure why -- I checked the noise floor of the AP with a 50 ohm Tektronix attenuator and it is the same as last evening when I did the measurement.

Perhaps it was the aroma of roasting chicken which influenced the measurements, I don't know...
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Old 7th October 2009, 02:02 PM   #47
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Measurement of such low values is quite a pain to do reliably. Lots of things can be questioned about the number that comes out. Just like you don't want to hear the word "proof" during a phd defense, so you don't want to hear "instrument calibration" in a home setup for low noise measurement.

I've given up on absolute value measurements, instead, I go for ranking. I find that suits my purpose much better. Of course, it brings no laurels or papers or articles, it's just good for my personal conclusions of how something is worse or better than something else.

Jack, do you intend to measure the output impedance of your regs? That to me is just as important as the intrinsic noise of the device. I don't have the setup to run full spectrum measurements of output impedance. Instead, I just measure the p-p modulation on the output of the regulator with a sine wave of some mA load, at a few frequencies, 100Hz, 500Hz, 1kHz, 3kHz, 5kHz, 10kHz, 15kHz, 20kHz. That gives me a very good idea of what's going on.
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Old 7th October 2009, 02:34 PM   #48
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Proof or "poof"?

Jan sent me a reference to a white-paper on the AP website for impedance measurement. I appreciate the work that went into the 1995 articles.

Decades ago my university had a shielded room for this kind of stuff. One of the instructors said that when you ran experiments the Penn Central trains (now Metro North -- about 2000 feet away) could be seen on the detectors if you weren't in the shielded room! For the life of me I don't know why they took the structure down.
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Old 7th November 2012, 02:41 PM   #49
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Quote:
Originally Posted by jackinnj View Post
Well, forget about the LME49600 Regulator -- here are some results --

A Weighted level measurements -- a.c. coupled with 15mA load -- shielded by my Oreo Cookie Tin:

78L15 (ST Micro) RMS 26.9uV, Quasi-Peak 44.3uV
LM317 (National, No adj bypass) RMS 181uV, Q-Peak 289uV
Super-Regulator (LT1028 error amp) RMS 2.2uV, Q-Peak 3.6uV

LME49600 (LM4040 Ref) RMS 347uV, Q-Peak 564uV

My advice to you, young man, get the Super-Reg boards from Old Colony and stop wasting your time.

The Super Reg is only slightly noisier than the battery.
I know this is a pretty old thread, but, I finally got around to measuring my layout of the LME49600 regulator. The DC supply to my board is an old HP lab supply, I measured it un-loaded, with with a HP3562 spectrum analyzer. The board was out in the open, no shielding, LM4040 Ref running at 6.6v out. I saw 3.2uV at 1k, have a spike of 6.6uV around 10k, which I suspect is environmental noise and some spikes at 60,120 adn 180hz. Different from Jack's layout, I have bypass caps on the LME49600, though none for the LME49710.

I will put a load on it and put it inside a tin and measure again.

Ken
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Old 10th November 2012, 01:44 AM   #50
klewis is offline klewis  United States
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The following are my measurements of the LME49600 regulator as shown in the National (not TI) application note for the LME49600. I'm going to try making a new version of this with a hopefully improved layout. I hope the new layout will kill the 10kHz spike.
Attached Images
File Type: png LME49600_regulator_0-2k.png (38.0 KB, 248 views)
File Type: png LME49600_2k-12k.png (41.0 KB, 242 views)
File Type: png LME49600_0-100k.png (37.6 KB, 238 views)
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