How to make 12v adjustable current power supply

How to make 12v adjustable current power supply

In this project we learn how to make 12v adjustable current power supply easy at home with the help of video and circuit diagram. using this circuit you can adjust current 0.1 ampere to 10 ampere and voltage fix 12 volt. Because we also use LM7812 voltage regulator for regulate voltage.
For making this project we needs some components.

How to make 12v adjustable current power supply

Components:

• 12v or 24v 10 amps Transformer
• TIP3055 Transistor
• LM7812 Voltage Regulator,
• BD139 Transistor,
• 4700uf, 35v Capacitor,
• 220uf, 35v Capacitor,
• 10k Variable Resistor,
• 10A10 diode,
• 1N4007 diode,
• Heat Sink,
• Soldering wire,
• Soldering iron, 
• PCB Board

1st make circuit diagram, 

• Transformer has 2 side, 

  

  12v adjustable current power supply circuit diagram

• Primary side use for 220 volt input power, 
• Secondary side has 3 pin, 
• Connect 10A10 diode with 1st pin of transformer, 
• If you use 12-0-12 transformer then leave 2nd wire and 3rd wire use for ground wire, 
• Now positive side of 4700uf capacitor connect with 2nd side of diode, 
• And negative side connect with ground wire, 
• Now input wire of voltage regulator connect with 2nd side of diode,
• And 1N4007 diode connect with ground wire of voltage regulator like diagram. 
• Now collector pin of BD139 transistor connect with output wire of voltage regulator,
• Variable resistor has 3 pin.
• Middle pin connect with base of BD139,
• 1st and 3rd pin connect with collector and emitter pin of BD139, like diagram,
• Now TIP3055 transistor base pin connect with emitter of BD139,
• And now collector pin connect with input pin of voltage regulator,
• Now positive side of 220uf capacitor connect with emitter pin of  TIP3055,
• Negative side of capacitor connect with ground wire, 
• And finally emitter pin of tip3055 use for positive output and ground wire use for negative output. 

BD139 NPN Transistor has 3 pin.

• 1st Emitter 
• 2nd Collectors
• 3rd Base

TIP3055 NPN Transistor has 3 pin. 

• 1st Base
• 2nd Collector
• 3rd Emitter

We learn it more battery with watching video.

Video of how to make 12v adjustable current power supply:

Why TIP3055 Transistor very heating?

When we adjust current then total load transfer on Transistor and transistor very heat up. So must use large heat sink with transistor. and also use cooling fan. if you dont do this then your transistor burn soon.

How we adjust current?

you can adjust current using 10k variable resistor 0.1 amps to 10 amps. for example if our requirement is 2 ampere then simple adjust it in 2 amps with the help of multi meter.