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48 VDC from 60 V unregulated
48 VDC from 60 V unregulated
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Old 12th June 2019, 07:43 PM   #31
Elvee is offline Elvee  Belgium
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Quote:
Originally Posted by donpetru View Post
Another solution would be to use a TL783 - see chapter 9 of the PDF file below, there are some useful examples:
http://www.ti.com/lit/ds/symlink/tl783.pdf
Yes, that is one of the option I recommended

Quote:
Originally Posted by brucetassin View Post
I found this online. I breaded boarded it to see if it works and it did.
It worked up to over 300 vac on the input and regulated down from
that. I also used a 50 vac transformer and it worked down from that.
I did not use it in a circuit so I don't know how it sounds.
It is not a regulator: it is a crude voltage reducer + protection.
In addition, it will require a much higher dropout voltage than what is available here
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Old 12th June 2019, 09:27 PM   #32
indaco is offline indaco
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Quote:
Originally Posted by Elvee View Post
The diodes will not protect against this condition, you would need a transil across the regulator.

Here is an example of simple regulator, equipped with an overcurrent protection and a zener bypass:
Thanks, I will simulate it and see. The circuit seems to be good, I've just left a TIP122 left.
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Old 12th June 2019, 09:32 PM   #33
indaco is offline indaco
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Quote:
Originally Posted by brucetassin View Post
I found this online. I breaded boarded it to see if it works and it did.
It worked up to over 300 vac on the input and regulated down from
that. I also used a 50 vac transformer and it worked down from that.
I did not use it in a circuit so I don't know how it sounds.
If I can say, I know and tested this circuit and it is not much fine. It's useful for higher voltages and an output within 100 mA max.
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Old 13th June 2019, 12:11 AM   #34
wg_ski is offline wg_ski  United States
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Quote:
Originally Posted by indaco View Post
Thanks, I will simulate it and see. The circuit seems to be good, I've just left a TIP122 left.
Why would you need to simulate anything? LVís circuit is simple, almost foolproof, and easy to analyze by hand with a pencil, paper and a calculator.

And you donít need to be limited to a TIP122. Any darlington or darlington connected pair with sufficient ratings (calculated with pencil and paper) will work.

I like this circuit a lot - I prefer something like this as opposed to using 3 terminal regulators in most applications. Especially ones where capacitive loads can risk the regulator misbehaving and blowing out a board full of ICís that have to be replaced....
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Old 13th June 2019, 05:11 PM   #35
PRR is offline PRR  United States
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Quote:
Originally Posted by indaco View Post
A transitorized zener regulator, simple, good...but doesn't the zd add some "noise" for the amp circuit?
So? There's always some noise. Low noise was not in the requirements. IMHO a 48V 500mA load is likely to be a High Level stage and not noise-critical. If this is really a Phantom Power supply for 48 microphones, a little filtering might be wanted, but Phantom is fairly uncritical of supply noise, and it is customary to put say 220r+220uFd on each output.

Quote:
Originally Posted by wiseoldtech View Post
The OP requires only a 12 volt drop from 60V to a regulated 48V, so there's no problem. The LM317T would only be absorbing 12 volts, so where is the problem?
At start up. The input power goes to 60V with full force of the power company through the transformer. Any capacitor on the regulator output will start from ZERO and lag significantly behind the rise of input of raw DC. This does not always pop a '317; to puzzle the builder, sometimes it works a dozen start-ups before failing.

Also, for self-protected regulators, in overload. Load rises over 1 Amp. Regulator turns-off. Now it feels the full 60V input voltage. The cut-off breakdown may be a little higher than the 35-40V operating breakdown, but maybe 20% and not always 50% over.
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Old 13th June 2019, 07:35 PM   #36
Vovk Z is offline Vovk Z  Ukraine
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48 VDC from 60 V unregulated
Quote:
I did not use it in a circuit so I don't know how it sounds.
I din't know how it sonds too, but I use almost the same cirquit in high-voltage (500V) component tester. All ok.

Last edited by Vovk Z; 13th June 2019 at 07:41 PM.
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Old 13th June 2019, 11:06 PM   #37
indaco is offline indaco
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By suggestion of PRR in the previous post I tried this circuit, a series feedback voltage regulator, and works fine. I add picture of the components used.
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File Type: jpg 20190614_005151.jpg (420.9 KB, 20 views)
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