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Need Help: Make two 5V power supplies

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Don_dody

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Hi all,

In my project, I have to use four motors and they are require high current to operate. Because of this, I decide to make two power supplies which are LM2576 based and LM7805 based power supply. LM2576 based supply will be used to power the motors only while LM7805 based power supply will be used to feed the microcontroller and the other logic circuits.

For that purpose, can I build my power supplies like this:
ps.png

Most important one: Can I connect both of the ground together ?
 

ahmad1954

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probably you can use that circuit but I suggest transformer with 3 head. in this way 2 power supply separate from each other.
 

Don_dody

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I suggest transformer with 3 head. in this way 2 power supply separate from each other

I'm sorry, can you give more explanation. I didn't get it yet.

They are already connected together at the negative plate of C1.

So Can I use it? Is that allowed?
 

ahmad1954

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if you use transformer with 4 head, you have 2 separate transformer. after that you should use 2 bridge diode and capacitor for each of them. the main advantage of transformer with some head is you don't have to use several transformer.
 

Don_dody

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Then what about the ground? Can I still connect them?

I got confuse because the motor driver need ground also. If I make two separated power supplies, should I connect the ground to one of the supplies or connect them (both of the grounds) first, and then connect to the driver's ground ?
 

Don_dody

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Hi, Ive built the LM2576 based supply.

First: When I tested it, there is smoke coming from the 1N5822 diode. Did you know why this could happen?

Second: I decide to built the new one, then the 100uF capacitor is blown after a while. How can it happen?

Third: I'm not giving up, I tried to built the new one (the third), and the same problem occur, there is smoke near to the diode, and after that power gone.

I don't even build the 7805 based power supply yet.

Any suggestions?
 

Don_dody

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Exactly the same as post #1 but I don't even build the 7805 circuit yet.
 

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