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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.
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Old 20th September 2019, 09:20 PM   #211
Elvee is offline Elvee  Belgium
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My breadboard setup is still more or less operational, so I will make the ultimate simulation test: reality.

I shall compare the regular denoiser with a randomly chosen BC337-25, and the LoPo variant in exactly the same conditions, except for the resistors values.

This should settle the issue regarding the impedance level.

The resistors quality is something different: if I find suitable carbcomp in my stock, I shall also test them.
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Old 21st September 2019, 12:04 AM   #212
sgrossklass is offline sgrossklass  Germany
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Somehow I managed to miss this thread before. Very neat, I must say. If in doubt, I'd rather be using an LM317, a BC337 and a few passives than some exotic specialty part (which have a habit of becoming unobtainium eventually). Not like any sanely-designed circuit should actually require regulator performance like that, but hey - at least the power won't be the bottleneck. The only thing I don't like is the overshoot, probably a result of the two poles (related to the two coupling caps) being too close together.

I have to wonder whether you couldn't upgrade a (Darlington or MOSFET) cap multiplier to "super" level with a DeNoiser. I don't see why not. The result would appear to be looking an awful lot like a basic voltage regulator, just all AC-coupled, and presumably perform similarly as well. Sometimes you just want a clean supply, but don't care what it is within certain limits (a zener can be included to avoid overvoltage).
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Old 21st September 2019, 05:26 PM   #213
Elvee is offline Elvee  Belgium
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I have rebuilt the setup and made the comparison: with the "regular" resistor values, I arrived at 0.55µV total noise (10Hz-10kHz); IIRC, it is a bit higher than the previous results, but the transistor is different, it is a BC337-25, and and I didn't take the utmost care in the grounding scheme, etc., and it is a breadboard.

I then increased all the resistors by a factor 5: 1K8-->9K1, etc. except for the input protection resistor.
I left all the caps identical.
To my surprise, the degradation was barely noticeable: the noise reached 0.6µV.
So, reducing quiescent current by a factor 5 has ~no impact on noise performance.
The DC stability is certainly going to be affected though.

I then made a further test: I used carbcomp resistors for the two most critical ones: the collector load and the Out to Adj resistor.
There again, no significant change.


Quote:
Originally Posted by sgrossklass View Post
The only thing I don't like is the overshoot, probably a result of the two poles (related to the two coupling caps) being too close together.
Yes.
To make the correction as wide as possible, I used what I estimated as the largest reasonable coupling cap in the collector: 220µF, and the base cap was a tradeoff: for an extended subsonic response, it needs to be high enough, but the pole becomes close to the other one, resulting in some humping.
It could be made smaller, if VLF is not very important, or the 220µF can be made larger.
The nonoiser has more favorable impedance levels, and does not show this behavior (which is entirely avoidable if necessary).

Quote:
I have to wonder whether you couldn't upgrade a (Darlington or MOSFET) cap multiplier to "super" level with a DeNoiser.
It would certainly be possible.
The limitations of "simple" cap multipliers stem from the Early effect of the pass transistor, which limits rejection to ~60dB or thereabout.
With the denoiser, you could certainly add another 35dB, probably more because you have more leeway in the choice of impedances compared to a 317.
It is also possible to stay open-loop, and compensate the Early effect, but that's another story
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Old 22nd September 2019, 03:27 AM   #214
RickTH is offline RickTH
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Quote:
Originally Posted by Elvee View Post
I then increased all the resistors by a factor 5: 1K8-->9K1, etc. except for the input protection resistor.
That's radical , a factor 5 , but good to know that 2 or 3 times as much , like I want, will do no harm. With 9k1 , did you measure the Vce with ... 5 x 180k = about a 1M base resistor ? Did you keep the 47 ohm resistor the same or also x5 ?
What is the input protection resistor ?
Did you mean also the LM317 bias setting R times 5 ? So going from the 220 ohm to 1k2 over the 1,252 V ref ?

I just did tests with an 1k8 resistor there (but without the DeNoiser) , to test a low quiescent current regulator for a logic IC circuit , and it still works , but without load the output voltage is a few 10's mV higher. I seems 1k2 is the highest you can go to keep it safe with low current loads as not-doing-anything CMOS logic IC's.
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Old 22nd September 2019, 09:05 AM   #215
Elvee is offline Elvee  Belgium
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Quote:
Originally Posted by RickTH View Post
did you measure the Vce with ... 5 x 180k = about a 1M base resistor ?
As the collector resistor was also scaled in the same proportion, there is no significant change, except those due to variations in Hfe; and as I said, the exact Vce is unimportant.
Quote:
Did you keep the 47 ohm resistor the same or also x5 ?
What is the input protection resistor ?
The 47 ohm is the protection resistor, and I kept it
Quote:
Did you mean also the LM317 bias setting R times 5 ? So going from the 220 ohm to 1k2 over the 1,252 V ref ?
Yes, everything

Quote:
I just did tests with an 1k8 resistor there (but without the DeNoiser) , to test a low quiescent current regulator for a logic IC circuit , and it still works , but without load the output voltage is a few 10's mV higher. I seems 1k2 is the highest you can go to keep it safe with low current loads as not-doing-anything CMOS logic IC's.
All my tests were made with a 287 ohm load
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Old 22nd September 2019, 10:18 AM   #216
Elvee is offline Elvee  Belgium
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Quote:
Originally Posted by sgrossklass View Post

I have to wonder whether you couldn't upgrade a (Darlington or MOSFET) cap multiplier to "super" level with a DeNoiser. I don't see why not.
Here it is:
Improving capacitance multipliers

As expected, the improvement over the plain vanilla version is ~30dB
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Old 12th October 2019, 06:30 AM   #217
zjjwwa is offline zjjwwa  Poland
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D-Noizator: a magic active noise canceller to retrofit & upgrade any 317-based V.Reg.
Can DeNoiser be used together with the pre-regulator concept?
Where the first LT stabilizes the dropout between input and output of the second LT chip?
Would such DeNoiser Circuit be appended at the back of the preregulator,
or would it make sense to use two DeNoisers, as an integral follow-on module for each of the two LT chips?
...
What do you think, would the DeNoiser better the solution presented as the last picture on this webpage (boasting 100dB, or something?)
Using 3-pin regulators off-piste: part 4
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Old 12th October 2019, 08:14 AM   #218
Elvee is offline Elvee  Belgium
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Quote:
Originally Posted by zjjwwa View Post
Can DeNoiser be used together with the pre-regulator concept?
It could, but it depends on what you want to achieve.
A prereg (without denoiser) will double the PSRR, but the output noise will remain the same.

Quote:
Would such DeNoiser Circuit be appended at the back of the preregulator,
or would it make sense to use two DeNoisers, as an integral follow-on module for each of the two LT chips?
Thus, the logical place to place a denoiser is at the last regulator.

Note that the denoiser alone improves the PSRR by 30~35dB. Would you need a prereg anyway?
...
Quote:
What do you think, would the DeNoiser better the solution presented as the last picture on this webpage (boasting 100dB, or something?)
Using 3-pin regulators off-piste: part 4
The denoiser will beat the noise perf hands down, but it will not match the rejection.
However, with the Nonoiser, you will reach an even lower noise level, 125dB~130dB PSRR, plus one or two side benefits like stellar (µΩ-level) output impedance, simplicity (just one more transistor instead of a full regulator) and a dropout voltage halved....
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Old 12th October 2019, 09:13 AM   #219
zjjwwa is offline zjjwwa  Poland
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D-Noizator: a magic active noise canceller to retrofit & upgrade any 317-based V.Reg.
Quote:
Originally Posted by Elvee View Post
Unlike the Denoizator, this regulator is not suitable as a retrofit: even if you are ready to carry out the mods, it can only work properly and deliver its performances with Kelvin connections: the input, output and sense terminals need to be completed independent: any common ground will ruin it and bring it to the level of an ordinary regulator.
I do not fully understand this. Can you please draw this?
Your photos of the regulator show six connection pins:
Plus_in, Minus_in, Plus_out, Minus_out, Plus_sense, Minus_Sense.
From what points of the NoNoiser are these routed ?

I have a vague understanding that the Kelvin sensors on the output are separate leads from regulator to final load (but from which elements of the regulator?), and they "sense" what is going on at directly on the terminals of the load.
But how can you make Kelvin connections on the input? How can you separate the input ground from output ground?
The LT317 is basically a 3-terminal device, with a common ground for both input and output, so how can I "separate them" ?
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Old 12th October 2019, 09:20 AM   #220
zjjwwa is offline zjjwwa  Poland
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D-Noizator: a magic active noise canceller to retrofit & upgrade any 317-based V.Reg.
Quote:
Originally Posted by Elvee View Post
It could, but it depends on what you want to achieve.
A prereg (without denoiser) will double the PSRR, but the output noise will remain the same.
Thus, the logical place to place a denoiser is at the last regulator.
Note that the denoiser alone improves the PSRR by 30~35dB. Would you need a prereg anyway?
...
The denoiser will beat the noise perf hands down, but it will not match the rejection.
However, with the Nonoiser, you will reach an even lower noise level, 125dB~130dB PSRR, plus one or two side benefits like stellar (µΩ-level) output impedance, simplicity (just one more transistor instead of a full regulator) and a dropout voltage halved....
Many kind thanks for your inputs. The reason I asked about that acoustica.org last picture schematic, is because I actually implemented it some time ago within some of my DIY audio devices (DAC, CD transport), and was very much impressed by the resulting SOUND. Spectacular improvements to my ears (sound-scene, holography, black background, et al).
So now I am wondering about bettering that small circuit, in hope of achieving even better sound.
The thing that worries me is the statement regarding "Kelvin Sensing". The modified CD Transport basically uses a common ground throughout.
Although, I could do the Kelvin Sensing within the independent low noise power source that I built for the off-board low jitter clock. Hmmm...
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