Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

D-Noizator: a magic active noise canceller to retrofit & upgrade any 317-based V.Reg.
D-Noizator: a magic active noise canceller to retrofit & upgrade any 317-based V.Reg.
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 21st December 2018, 05:15 PM   #1
Elvee is offline Elvee  Belgium
diyAudio Member
 
Elvee's Avatar
 
Join Date: Sep 2006
Default D-Noizator: a magic active noise canceller to retrofit & upgrade any 317-based V.Reg.

A simple circuit that transforms a good, clumsy workhorse like the LM317 into a superreg so easily that you do not even need to cut a single track.
It must be too good to be true.... or

.................................................. .................................................. .....................
It's Christmas!!!

The present SOTA in VR noise cancellation is this:

D-Noizator: a magic active noise canceller to retrofit & upgrade any 317-based V.Reg.-cleanup1-gif

From Wenzel finesse regulator: Finesse Voltage Regulator Noise! |

Drawbacks are obvious:
a) Low current
b) Affects static and dynamic operation
c) Limited correction ability

Let us start with the basic regulator (including the additional bypass cap, since we strive for the lowest noise).
An additional source symbolizing the noise is shown explicitly.
The bypass cap is effective down to ~10Hz, but the level does not fall below 0dB.

D-Noizator: a magic active noise canceller to retrofit & upgrade any 317-based V.Reg.-dnoiz1-png

Now, let us add the D-Noizator piggy-back:

D-Noizator: a magic active noise canceller to retrofit & upgrade any 317-based V.Reg.-dnoiz2-png

The floor drops by more than 30dB.
The circuit works by changing the output node into an AC virtual ground.
Therefore, benefits do not stop at internal noise reduction: all the performances benefit: PSRR, output impedance.

Ultimately, the performances are limited by the discrete transistor.


What about the reality?

I made a test with ST and ONsemi samples. They behave as perfect clones, both with and without the D-Noizator.

D-Noizator: a magic active noise canceller to retrofit & upgrade any 317-based V.Reg.-dnoiz3-jpg

With just the cap, the noise is 16μV, as measured by a Levell TM3B.
With the D-Noizator, it falls to 2.5μV~3μV, which seems to indicate that the circuit doesnt deliver all of the promised improvement... except that the noise floor of the TM3 is also 2.5μV~3μV.
The TM3 is not a bad instrument, but it is very cheap, and very dated.
I would need to add a modern LNA to make meaningful measurements.

D-Noizator: a magic active noise canceller to retrofit & upgrade any 317-based V.Reg.-dnoiz4-jpg

It is more than promising, anyway.

Of course you cannot throw a large gain into the regulator's loop without consequences: it is now forced to operate at a gain much lower than unity, and without precautions, it oscillates like mad, which comes as no surprise.
However, compensation seems to be easily achieved, and very tolerant: a capacitor larger than 2nF was sufficient to stop oscillations.

A VLF peaking is visible in the response; it could probably be polished off by increasing the splitting of the poles, or similar measures
Attached Images
File Type: gif cleanup1.gif (3.7 KB, 2640 views)
File Type: png Dnoiz1.png (86.4 KB, 2654 views)
File Type: png Dnoiz2.png (71.1 KB, 2674 views)
File Type: jpg Dnoiz3.jpg (524.6 KB, 2541 views)
File Type: jpg Dnoiz4.jpg (304.5 KB, 2544 views)
__________________
. .Circlophone your life !!!! . . ♫♪ My little cheap Circlophoneİ ♫♪
Electrify your daily life!!! ....⚡⚡ ELEKTRIA ⚡⚡

Last edited by Elvee; 21st December 2018 at 05:22 PM.
  Reply With Quote
Old 21st December 2018, 07:22 PM   #2
Lingwendil is offline Lingwendil  United States
diyAudio Member
 
Lingwendil's Avatar
 
Join Date: Apr 2008
Location: Oakley California
Interesting. Wonder how well it will work for digital stuff like DAC supplies.
__________________
Check out My 6SN7 Push-pull Flea Amplifier project! PCB COMING SOON!
  Reply With Quote
Old 21st December 2018, 09:23 PM   #3
Elvee is offline Elvee  Belgium
diyAudio Member
 
Elvee's Avatar
 
Join Date: Sep 2006
Quote:
Originally Posted by Lingwendil View Post
Wonder how well it will work for digital stuff like DAC supplies.
It depends on two things: is the target supply using a divider for the voltage setting, and can you find a discrete transistor better than the regulator's internal circuitry? Note that even a fixed regulator could benefit from the fix, but from a practical POV, things would be much more difficult: you would need to isolate the reference terminal, which generally happens to be GND. Probably a detail for compulsive modders, but a serious obstacle for all the others.

In principle, you will always be able to find a discrete superior to the internal circuits of a VR, but with modern VR's, this is going to be difficult, and perhaps not worth the trouble. With 317 style regulators, it was easy, because the IC has to cope with everything, DC, AC, thermal stability at the same time. With a discrete, you can separate the AC and DC paths, which eases matters considerably. However, IC designs have become so much smarter that bettering them requires a significant effort. It is certainly possible, but any gain is probably going to be marginal, and if you want a real improvement, you need to design everything from scratch, not try to improve on something that is barely improvable
__________________
. .Circlophone your life !!!! . . ♫♪ My little cheap Circlophoneİ ♫♪
Electrify your daily life!!! ....⚡⚡ ELEKTRIA ⚡⚡
  Reply With Quote
Old 21st December 2018, 10:29 PM   #4
MarcelvdG is offline MarcelvdG  Netherlands
diyAudio Member
 
Join Date: Mar 2003
Location: Haarlem, the Netherlands
Nice circuit, like in all threads that you start!
  Reply With Quote
Old 22nd December 2018, 01:58 PM   #5
jackinnj is offline jackinnj  United States
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
D-Noizator: a magic active noise canceller to retrofit & upgrade any 317-based V.Reg.
Hat tip to Elvee. I ran some simulations of Z out and PSRR with Multisim:
Attached Images
File Type: png LM317_Elvee.png (28.4 KB, 391 views)
File Type: png LM317_Elvee_PSRR.png (27.5 KB, 402 views)
  Reply With Quote
Old 22nd December 2018, 04:37 PM   #6
Elvee is offline Elvee  Belgium
diyAudio Member
 
Elvee's Avatar
 
Join Date: Sep 2006
I have been able to refine the measurements: I remembered that one channel of one of my lab amplifiers is equipped with a OPA27.

This brought the noise floor of my test set-up to 0.75µV.
When measuring the D-noizator, I got 1.0µV.
This means that the actual noise is in the vicinity of 0.66µV.
Since the noise with the cap connected normally is still 16µV, the improvement ratio is 27.7dB, much closer to what the sim predicted.

Of course, the test is made on a breadboard, and the transistor is just an ordinary BC337-40 from Philips.

With a good PCB and a super low noise transistor, it would be possible to scrape a few tens of nV
__________________
. .Circlophone your life !!!! . . ♫♪ My little cheap Circlophoneİ ♫♪
Electrify your daily life!!! ....⚡⚡ ELEKTRIA ⚡⚡
  Reply With Quote
Old 22nd December 2018, 04:50 PM   #7
Mark Johnson is offline Mark Johnson  United States
diyAudio Member
 
Mark Johnson's Avatar
 
Join Date: May 2011
Location: Silicon Valley
D-Noizator: a magic active noise canceller to retrofit & upgrade any 317-based V.Reg.
Summary: low noise voltage regulator achieved using twelve electronic components, one of which is an integrated circuit.
  Reply With Quote
Old 22nd December 2018, 05:04 PM   #8
DontHertzMe is offline DontHertzMe  South Africa
No Morse
diyAudio Member
 
DontHertzMe's Avatar
 
Join Date: Jul 2013
D-Noizator: a magic active noise canceller to retrofit & upgrade any 317-based V.Reg.
Would the same principle apply for the LM337?
  Reply With Quote
Old 22nd December 2018, 05:23 PM   #9
PRR is offline PRR  United States
diyAudio Member
 
PRR's Avatar
 
Join Date: Jun 2003
Location: Maine USA
Quote:
Originally Posted by Mark Johnson View Post
Summary: low noise voltage regulator achieved using twelve electronic components, one of which is an integrated circuit.
You forgot "magic".
  Reply With Quote
Old 22nd December 2018, 05:31 PM   #10
Elvee is offline Elvee  Belgium
diyAudio Member
 
Elvee's Avatar
 
Join Date: Sep 2006
Quote:
Originally Posted by Mark Johnson View Post
Summary: low noise voltage regulator achieved using twelve electronic components, one of which is an integrated circuit.
Yes.
The piggyback alone (since the main use of this circuit is probably going to be the retrofitting existing regulators) requires 7 components

Quote:
Originally Posted by DontHertzMe View Post
Would the same principle apply for the LM337?
Yes, of course: use a PNP and reverse the polarity of E-caps.


Here is a slightly better tradeoff: the current consumption is increased, but the improvement factor is 38dB, and the VLF peak is mostly gone.

Going further probably makes little sense, since finding a transistor sufficiently good to capitalize on the gain is going to be difficult.
Attached Images
File Type: png Dnoiz5.png (109.9 KB, 945 views)
__________________
. .Circlophone your life !!!! . . ♫♪ My little cheap Circlophoneİ ♫♪
Electrify your daily life!!! ....⚡⚡ ELEKTRIA ⚡⚡
  Reply With Quote

Reply


D-Noizator: a magic active noise canceller to retrofit & upgrade any 317-based V.Reg.Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
PSU upgrade for DAC Magic Plus E30NA Digital Line Level 8 1st October 2014 12:00 PM
Higher-harmonic distortion canceller jkeny Solid State 0 29th January 2009 11:39 PM
LM3886 based Amp -Upgrade advice please. mikesnowdon Chip Amps 3 26th October 2008 12:53 PM
Active crossover - Voodoo magic? ShinOBIWAN Multi-Way 5 24th February 2005 02:34 AM


New To Site? Need Help?

All times are GMT. The time now is 11:14 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki