Electronics > Projects, Designs, and Technical Stuff
What is "floated" linear voltage regulator?
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001:

--- Quote from: spec on November 21, 2018, 07:54:59 am ---

The term floating is really a misnomer, because all voltage regulators are connected one way or another to 0V, they must be to function. Having said this, it is possible to have the regulator actually isolated from the 0V line by using an opto isolator for example.

Getting back to the 200V supply, you would connect a 100R resistor between the output and sense terminals and a 15k9 resistor from the sense terminal to 0V.

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Thanx a lot! Can You tell me what reference is used in floating designs? How it "feels" ground potential?
spec:
No probs.

I will put together a simple explanation and include a discrete circuit which hopefully will illustrate the way that the feed back works in a floating PSU.

You can greatly simplify electronics by forming simple models of circuit elements. One simple model, which has great relevance to PSUs is this: "An opamp will do all it can to make its non-inverting and inverting inputs the same.  And the only thing it can do is to change its output voltage."  That simple concept helps you understand what an opamp is doing in most circuits without any heavy math or circuit analysis.

There are simple models for all elementary components: resistors, capacitors, inductors, transformers, diodes, BJTs, MOSFETs, and opamps.

And here is a simple model of a PSU: "A PSU is an opamp with a high output current capability."
capt bullshot:

--- Quote from: 001 on November 21, 2018, 07:55:41 am ---
--- Quote from: capt bullshot on November 21, 2018, 06:40:15 am ---If you can read German, here's some schematics and documentation of Heinzinger "Transistornetzteile" (Made in Western Germany  ::):
https://cb.wunderkis.de/wk-pub/heinzinger/

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Awesome link. But all pdfs are unawailable now (It says: "You don't have permission to access /wk-pub/heinzinger/0390 30258 LNG 50-4.pdf on this server."  :blah:)
Can You share it here?

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Seems you'll have to turn on the Referer on your browser, or try another browser. I'm using Firefox, and it works for me. This is a configuration I made to my webserver to keep search engines and other scrapers away, maybe it blocks you unwanted. If your browser provides the correct referer, you should be able to get the files.
Forget the above, and try again, apparently I didn't set the access rights to the files correctly, so the server couldn't access them at atll.
not1xor1:
Here is an example of a voltage regulator (current regulation omitted for clarity).
BTW probably it would be more appropriate to define it bootstrapped rather than floating.

Also, these pictures show the advantage of having variable Vref vs. variable feedback.


variable feedback


variable voltage reference
capt bullshot:

--- Quote from: not1xor1 on November 21, 2018, 09:01:17 am ---BTW probably it would be more appropriate to define it bootstrapped rather than floating.

--- End quote ---
"Bootstrapped" usually refers to a supply voltage above the maximum voltage level in the system, stored in a capacitor that gets charged while the output swings lower. It's a classic technique in some audio amplifiers, and often used in MOSFET driver circuitries. Bootstrapping won't work on a stable DC output (which is desired for a lab power supply).
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