Introduction: Very Efficient But Crude DC Power Supply :)

About: Kedar Prabhudessai, made in India :) electronics maker and Nikola Tesla fan.

Hello makers !

Today i just build this small power supply, today morning i was getting bored :/ and I wanted to build something. Suddenly i realized that, i have one 12-0-12 transformer and a pair of buck-boost converter laying inside my drawer and, there i got an idea to build a simple dc power supply from it. It is kind of crude build but it can power your projects very efficiently and it will not take a lot of space.

Step 1: Bill of Componets

1. Transformer: 12Vdc, at least 2amps for good performance( center-tap is not necessary)

2. Rectifier: 4x 1N4007 diodes for bridge rectifier or bridge rectifier IC with 2amps rating.

3. Capacitor: 220uF, 50v (I used 1000uF ,35V because that was onl available with me )

4. Switch: A2-way switch.

5. Buck-converter: LM2596S module

6. Boost-converter: XL6009 module

(they r many more buck-boost modules available u may choose according to your need)

7. Binding posts: output connectors.

8. Enclosure: a plastic box prefferably

9. power cord: a wire with plug attached for transformer's input.

Tools used are.....

soldering iron , wire stripper, glue gun.

Step 2: Diagram, Connections and Why I Didn't Use 78xx Linear Regulator If You Are Wondering :p

connections are simple as shown above in the diagram. i didn't use center tap, but i used the end wires to get 24 volts ac. then i used rectifying I.C to convert ac to dc.I used I.C because I salvaged it from an old PCB so i need not take trouble to solder four diodes to make bridge. the rectifier output is pulsating dc and we need to convert it to a smooth dc voltage. this is done by the capacitor connected in parallel. 220uF capacitor is enough but, u need to take care of voltage rating since the capacitor charges to peak voltage of pulsating ac. mine is 25V ac which will charge capacitor to 32V dc peak so i used 35V rated capacitor. the i connected it to a 2 way switch which i used to switch between buck converter and boost converter. and the output is given to 3 binding post,connectors one of which is common ground.

Now the biggest question " Why the heck i used this fancy thing called buck-boost converters?!"

well this is for those who didn't use them... if u know what i m talking about proceed to next step :)

there are many makers use ICs like 7805 or 7812 or 317T , these are actually called linear regulators. they actually regulate dc to give constant set output. but they are very inefficient as they drop out "extra" voltage and waste energy. for eg; if u give 10V to 7805 it will give 5V output but it will dropout extra voltage across its internal resistor which leads to lot of energy wastage.therefore you loose more and more power as heat as u draw more current so we use that big heat sink to protect it from itself. so this method is out of time now. u can do better use of them y using them as voltage reference in your projects.

now look at the buck boost converters. they are kind of switching mode supply which store energy and use them efficiently. for more info, google it there is lot to learn about them. for comparison, these r like 80% to 92% efficient then conventional linear regulators.

now u understood the concept everything is easy now.

Step 3: Prepare Your Enclosure.

Now take the box and make holes in it to put connectors and wires. use drill if u want but i used soldering iron hot tip to get things done fast. attach switch, binding post and make a small hole to insert wires.

Step 4: Prepare Regulators.

Desolder the potentiometers from both the modules and extend them using some wires, so that we can arrange them according to our convenience. remember the orientation of the pots while soldering.

Step 5: Soldering Everything Together

Now solder everything together according to the diagram. after soldering insulate joints with insulation tape. fix everything with a glue inside the box. I used glue gun to stick everything in the box and also insulate some hard to reach joints. i also fixed both voltage variable pots to the top lid for easy access.

Step 6: Finishing Evrything !

finally close the box and label everything. you r done :)

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