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Using the LM317 with higher voltages
Using the LM317 with higher voltages
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Old 18th November 2019, 11:29 AM   #71
carlmart is offline carlmart  Brazil
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OK, this is an alternative wiring for a doubler as applied by Nelson Pass on his A75 amplifier.

I did retain the D9 zener, but moved all the diodes and caps following what Pass did.

Some questions to understand this simulation, which I never did:

1) Why don't we get smooth DC at the outputs?

2) Why connecting the doubler from main high current bridge instead of directly to the AC output?

3) Why don't we get double the voltage at the boosted output? Shouldn't it be +/-100 VDC?
Attached Images
File Type: jpg Pass A75 power supply with doubler.jpg (102.8 KB, 108 views)
Attached Files
File Type: asc Pass A75.asc (3.4 KB, 3 views)
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Old 18th November 2019, 12:54 PM   #72
carlmart is offline carlmart  Brazil
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My question over the power amp low current supplies seems to be almost settled for me. And the questions arising seem to be quite minor.

Now I will open another thread to choose a regulated power supply to be used on some RIAA preamps I will be building.

My first idea had been the superregulator, but it has its quirks. So I am considering other options.

I got quite excited when I saw your NoNoiser regulator and its comparison with Jung/Didden specs.

So this is what I plan to propose on that thread: a direct comparison.

One thing I will have is real LTSpice sims comparing several superregulators around.

The next thing, which I don't know if it's possible, is to do actual measurements of the resulting DeNoise and NoNoise regulators.

I already have some super-regulators comparison curves carried on by Linear Audio which I don't know if I can upload to the forum. Will certainly need authorization from Jan Didden to do so.
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Old 18th November 2019, 01:31 PM   #73
jan.didden is offline jan.didden  Europe
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Quote:
Originally Posted by carlmart View Post
My first idea had been the superregulator, but it has its quirks.
[]
I already have some super-regulators comparison curves carried on by Linear Audio which I don't know if I can upload to the forum. Will certainly need authorization from Jan Didden to do so.
Carl what quirks are that?

And yes no problem uploading those measurements. Are those the ones by Jack Walton? Most are available already here: https://linearaudio.net/downloads .
But you need to scroll down almost to the end.

Jan
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Old 18th November 2019, 02:19 PM   #74
carlmart is offline carlmart  Brazil
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Jan,

Probably no quirks at all. My exaggeration, as they were my first choice in the regulators I plan to use.

The problems that happened in the past have been dealt with by Walt and you, and it's probably the most popular high-grade regulator around.

You do have to follow the recommendations stated by the designers, and maybe that's what I called "quirks". It's not like some other regulators that were less sensitive in that area. But it's the price to pay to have a better regulator.

I believe the measurements I refer to are Walton's. If I'm allowed to upload them on the thread they would be easier to refer to.
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Old 18th November 2019, 02:33 PM   #75
jan.didden is offline jan.didden  Europe
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Carl, by all means, upload them. No problem.

Jan
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Old 18th November 2019, 06:28 PM   #76
Elvee is offline Elvee  Belgium
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Quote:
Originally Posted by carlmart View Post
I did retain the D9 zener, but moved all the diodes and caps following what Pass did.
Why did you vandalize the circuit in this way? You rendered it non-functional and added useless components.
If you tried to fix this "problem", I also provided a variant addressing that:
Quote:
1) Why don't we get smooth DC at the outputs?
You wanted the boosted rail to track the main V+, and that's exactly what this variant does (ripple included, obviously).
You cannot have one behavior and its opposite at the same time in the same circuit: you will have to make a choice.
Here is the non-tracking, smooth version again:

Using the LM317 with higher voltages-ampps4-png

Quote:
2) Why connecting the doubler from main high current bridge instead of directly to the AC output?
To reference it to the main V+, to avoid this:
Quote:
3) Why don't we get double the voltage at the boosted output? Shouldn't it be +/-100 VDC?
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File Type: png AmpPS4.png (69.8 KB, 146 views)
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Old 18th November 2019, 07:25 PM   #77
carlmart is offline carlmart  Brazil
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No, you got it all wrong.

I didn't vandalize your circuit. That would be a lack of respect, and that's the last thing I wished to do.

What I did was sim the Pass A75 regulator and asked why you had connected the booster parts in a different way than what Nelson Pass had done it?

You can see that I named the asc file that way too.
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Old 18th November 2019, 08:12 PM   #78
carlmart is offline carlmart  Brazil
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Quote:
Originally Posted by Elvee View Post
You wanted the boosted rail to track the main V+, and that's exactly what this variant does (ripple included, obviously).
What I thought to boost was not the main V+ rail, but the AC feeding the large current bridge. Then smooth it, then adding the regulator.

You seem to be proposing a different approach, which I don't quite understand, with a zener diode. Can you explain that?

It seems that it starts as double, or it seems the zener is limiting voltage the booster can get to. Am I right?

My purpose is to get this doubler not to affect anything with additional noise, for instance. On Pass A75 supply the extra voltage is dissipated on the regulator's output transistor, even if voltages were lower.
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Old 18th November 2019, 08:25 PM   #79
Elvee is offline Elvee  Belgium
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As I said previously, the circuit is a capacitive supply*, which is loosely based on the doubler topology, but with the front cap small enough to act as a (lossless) ballast.


Without the zener, the final voltage would reach 3*V+

*Search this expression
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Old 18th November 2019, 11:29 PM   #80
carlmart is offline carlmart  Brazil
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OK, I will try that capacitive supply for the low current booster.

I imagine there's no way to, but can we trim the regulated voltage output on the single transistor regulator?

That would certainly be a good reason to go back to the 3-transistor regulator, because we have a trimpot there.
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