Dual Power supply circuit needed

M

Melfior_Ra

New Member

• Mar 3, 2013

• #1

Hi all.
I need a circuit diagram of a dual variable power supply with short circuit protection.

I need an output current of max. 2.5 A. The input voltage is around of +/-23 v after rectifier and smoothing capacitor.

Thank you In advance.

PS : A PCB it will be nice

 

crutschow

Well-Known Member

Most Helpful Member

• Mar 3, 2013

• #2

Is the ±23V input voltage two separate voltages measured to ground? You need separate voltages for a dual supply.

 

M

Melfior_Ra

New Member

• Mar 3, 2013

• #3

yes they are separate .I have a transformer with mid tap point, and between tap point and the other two wires i meassure around 18V ac which means around 23 v dc after filtering .
My english it is not so well so i will post a picture of the transformer:

 

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crutschow

Well-Known Member

Most Helpful Member

• Mar 4, 2013

• #4

Here's a simple circuit but it's only good for about 1.5A. You could increase the current by substituting a LT1033 negative regulator and a LM350 positive regulator to replace those shown. The will both need to be on good heat sinks.

 

M

Melfior_Ra

New Member

• Mar 4, 2013

• #5

Thank you.
I also found a circuit with op amps for positive side and i adapted for negative side. I am not sure if LM358 is suitable for this. I will attach the circuit, and please let me know your opinion.
Thank you

 

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• dual.psu.png

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J

Jaguarjoe

Member

• Mar 4, 2013

• #6

If you look at the LM317 regulator data sheet, near the back where the applications are, you will see how to add a pass transistor(s) to the 317 to get higher output current. This is magnitudes simpler than the circuit you found and will probably work better too.
There is a negative regulator that is the 317's mate.

 

M

Melfior_Ra

New Member

• Mar 4, 2013

• #7

A negative regulator is 337. I know about that and i will probably build a psu with those two. But I was asking if the circuit that i posted is good and if it will work in real world.

 

crutschow

Well-Known Member

Most Helpful Member

• Mar 6, 2013

• #8

From a cursory look it would appear that the circuit you posted would work, but of course it's has significantly more parts then the supplies using IC regulators.

 

M

Melfior_Ra

New Member

• Mar 6, 2013

• #9

Yes I know, but it is for training and for adding some experience after 2 years of self learning. I have already build a regulator with 317 and 337 and I had an unpleased surprise : I bought 2 LM337 from the same place but after building and testing the circuit, the voltage reference of those two was 0.7V instead of 1.25. Yesterday i bought another one frome another store and now the reference is 1.12V which I think is not perfect but at least is not 0.7V. Now, as I said I want to build this circuit and see how it works.
Thank you again for everything.

 

crutschow

Well-Known Member

Most Helpful Member

• Mar 6, 2013

• #10

Sounds like you need a more reputable supplier.