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Old 12th June 2011, 02:02 PM   #111
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OK.

How should I handle the transistor-modified regulator if I want to use it for higher voltages, like 60 volts? I mean keeping the improvements.
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Old 13th June 2011, 08:25 PM   #112
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The improvements stand. And there is no problem to using a 3x7 at voltages above 37v in the datasheet. That '37v' is maximum differential between input and output voltages allowable (subject to thermal constraints)

The trick is ensuring the LM317/337 is not exposed to more than about 30v differential from IN to OUT during startup and normal running.

The easiest way to do this is to use a large zener diode , say 15 or 18v , min 1.3W or 5w rating preferrd, in place of th reverse-bias diode between IN and OUT pins. Then, when the PSU starts-up, the zener avalanches until this voltage differential diminshes to something the regulator can withstand. At swtch-off, it behaves like the recommended diode. The zener only needs a voltage rating of a volt or two greater than the expected input-output differential so that it is 'out of circuit' during normal operation.

If you need to stand-off very high voltages the extended datasheet contains several suggestions - up to 2000V!
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Old 18th June 2011, 12:50 PM   #113
io is offline io  Hungary
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Hi

I use this low-impedance analog LM317/TL431 5 volts to Wolfson DAC.
simple

io
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Old 18th June 2011, 03:08 PM   #114
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Really good LR on that IO Shunt -- I would like to confirm it experimentally:

Click the image to open in full size.

I get impedance of around 2milliOhms which is consistent with your chart.
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Old 18th June 2011, 03:43 PM   #115
io is offline io  Hungary
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Hi
Yes it is.
intermediate version is stable curves (bond will not be published)
and bottom of today (srb-Snoise)
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Old 18th June 2011, 04:18 PM   #116
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by io View Post
(bond will not be published)
Quote:
and bottom of today
What do you mean in these two phrases?
__________________
regards Andrew T.
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Old 18th June 2011, 04:19 PM   #117
io is offline io  Hungary
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mid-development version, stable operation
Top line probe gnd,
bottom line power ON
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Old 18th June 2011, 08:27 PM   #118
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Quote:
Originally Posted by io View Post
Hi
Yes it is.
intermediate version is stable curves (bond will not be published)
and bottom of today (srb-Snoise)

Are these curves for real or simulations?

The impedance curve gets to improve on the Jung Super Regulators?

They were 100 microohms at a 10K frequency:

http://waltjung.org/PDFs/Regs_for_Hi..._Audio_2_B.pdf

How can that be possible without the massive feedback in Jung's regulator?
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Old 18th June 2011, 08:59 PM   #119
io is offline io  Hungary
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upgrade now circuit
simulations 100hz-1Mhz= max 290 nanoOhms
real? I can not be measured
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Old 18th June 2011, 09:19 PM   #120
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That sim performance absolutely will not be what you get if you build one - the TL431 will dominate, it can be a noisy little sod - and does not have much gain at all; certainly not enough to drive output Z down to these levels, or maintain it there to a few 10s of khz, let alone Mhz.

Last edited by martin clark; 18th June 2011 at 09:38 PM.
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