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6-V to 5.2V linear regulator

petelms

Apr 13, 2022
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Hello!

I would like to know how it is possible to make a linear regulator from 6-V to 5.2V. I have already made a little board like this (mine is with 6-V to 5-V regulator) on Youtube:


But the problem I'm having is that my device needs 5.2V and 5.0V is not enough. I want to make a linear voltage regulator, not any switching one.

Thank you!
, Pete.
 

bertus

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Nov 8, 2019
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Hello,

A voltage difference of only 0.8 Volts will be quite a challenge.
The 7805 shown in the video already needs about 2 Volts difference.
The BA00CC0 needs only 0.5 Volts difference.

Bertus
 

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petelms

Apr 13, 2022
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Thanks for the answers! My load current will be at least 1.5 amps. 3 amps would be the best.
 

bertus

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Hello,

The BA00DD0 will be able to handle 2 A.
You will not find a regulator for 3A.

Bertus
 

CircutScoper

Mar 29, 2022
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Hello!

I would like to know how it is possible to make a linear regulator from 6-V to 5.2V. ...

But the problem I'm having is that my device needs 5.2V and 5.0V is not enough. I want to make a linear voltage regulator, not any switching one.

Thank you!
, Pete.

Hi, Pete

Question: What's the source of your 6V input and how stable is it? For example, if it's unregulated or coming from a battery, it would be pretty fanciful to imagine that it's stable to 0.8V (13%) in the first place. Have you measured it under a 3A load or is this all theoretical?
 

petelms

Apr 13, 2022
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The source is a normal 6-v battery. I would need 5.2V from it. 3A load is theoretical. I might get along with 1.5A.
 

CircutScoper

Mar 29, 2022
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The source is a normal 6-v battery. I would need 5.2V from it. 3A load is theoretical. I might get along with 1.5A.

Then even if it is a LARGE battery, you will likely NOT have a true 6V for input to the regulator -- at least not for long. For example, here's a typical discharge curve for an alkaline D cell. Note the immediate drop when the load is first applied.

main-qimg-b2be82a994828d342da316a7a59ce1ca


To see what reality holds in store for your battery, put a 4 Ohm (at least 10W) resistor across your battery and watch what happens with an accurate voltmeter.
 

CircutScoper

Mar 29, 2022
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The source is a normal 6-v battery. I would need 5.2V from it. 3A load is theoretical. I might get along with 1.5A.

PS: Having no idea what you think a "normal 6V battery" might be, I used 1.5V alkaline D cells as an example of a fairly "large" battery. Their typical nominal amp-hour rating is ~15AH. But as you can see from the graph above, a 6V battery made from four of them connected in series would drop below 4 x 1.3V = 5.2V in just a (very) few minutes when connected to a 2A load.

So the good news is you may not need a regulator at all!
 

Martaine2005

May 12, 2015
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Why not just put a diode in series?
Would approx 5.3V be too much?.


Martin
 

Bluejets

Oct 5, 2014
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I'm wondering why the op has such a dislike for a dc dc converter.
 

petelms

Apr 13, 2022
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Yes, normal battery can really mean anything. -:) When I said "normal battery" I actually meant huge 6V 140ah battery. And the reason why I want to use linear regulator is that I want to get rid of the EMF interference which normal switching DC-DC converters have.
 

petelms

Apr 13, 2022
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Why not just put a diode in series?
Would approx 5.3V be too much?.


Martin
This sounds intresting! How do I put diodes in series? I'm beginner with these so I would need very clear instructions. -:) What kind of diodes? And is it 5.3V the lowest you can get from 6-V battery with diodes?
 

bertus

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Hello,

A standard diode will drop about 0.7 Volts.
A shottky diode will drop about 0.3 Volts.

Bertus
 

Bluejets

Oct 5, 2014
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Your 6v battery could be as much as 7.0v when fully charged and possibly as much as 8v while under charge conditions.
How did you intend to deal with that aspect?
 

kellys_eye

Jun 25, 2010
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my device needs 5.2V and 5.0V is not enough.
....and just what 'device' is it that's so voltage critical?

We need ALL the information to make a reasoned response - if we end up saying 'you don't need anything, just use the 6V' after numerous posts we won't be thanking you for wasting our time.......
 

CircutScoper

Mar 29, 2022
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Yes, normal battery can really mean anything. -:) When I said "normal battery" I actually meant huge 6V 140ah battery.

That's good news. Then all you have to worry about is its temperature coefficient -- about -0.01V/oC if it's lead-acid, although you didn't say..
 
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