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[SOLVED] Power supply short circuit protection

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Ogu Reginald

Ogu Reginald

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I am building the power supply with short circuit protection whose diagram is on the attachment, but the problem is that the two resistors in the diagram are out of reach. Please can anyone help me with a better diagram or recommend a regulator IC (variabla 2V-about 35V) with in built short circuit protection and can handle upto 3Amps.

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Please I need replies urgent.
 

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The .7 and .07 ohms form a 10-to-1 resistor divider.

You can hook up low-ohm resistors in parallel to obtain these values.

To obtain .07 ohms using copper wire, it can be made from 8 inches of 30 AWG. Or 5 inches of 32 AWG. Etc.

The 0.7 ohm must carry 3 amps, so thin wire is not workable.

Do you have a 1 ohm, 5 or 10 watt type? (Probably rectangular sandstone?) Or 0.82 ohm?

If it's like one that I broke apart, you can gouge or ***** or break the coating (carefully) and expose a resistive wire inside.

It may not accept lead solder, but maybe you can use some kind of solder or welding, to attach your positive supply wire to the resistive element, 1/10 length from the end. That would be the same as what you need.
 


Switching regulators such as L4975 and L4977 have inbuilt current limiting circuitry.
 

Can the regulators you mentioned above handle upto 3Amps?
 

Yes. L4975 is rated at 5A max. L4977 is rated at 7A max. You may also take a look at L4964, which is rated at 4A max.

You can find the circuits in the datasheets.

Hope this helps.
Tahmid.
 

Can the regulators you mentioned above handle upto 3Amps?
 

Ogu Reginald said:
Can the regulators you mentioned above handle upto 3Amps?
Click to expand...

LM338K can handle 5A without problems.

LM338K have :
- Shortcircuit protection
- Thermal shutdown protection
- Current limiter


Trust me, I use LM338K sucessfully many years for charging Lead-Acid batteries.
 

What do you people mean by switching regulator.

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What do you people mean by switching regulator.

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What do you people mean by switching regulator.
 

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