Project 101: Variable DC Power Supply 1.25-30 Volts (Introduction)

A Variable DC Power Supply (VPS) is a device that supplies electric power to an electrical load and, as the name implies, allows the user to vary or change the DC output voltage within the specified voltage ranges.  - which is the only difference compared to a Regulated Power Supply that spits out a constant output voltage.

 A power supply is a must have for any person engaging in any electronics hobby for testing your electronics projects in the future.




You can buy power supplies of different voltage ratings at your local electronics store, but making your own working device has that positive feeling of accomplishment and as a plus side you can customize your power supply any way you like which is great for hobbyists!

Now I would like to break down my journey into four steps to minimize the length of this post, they are:

1.) Designing the Power Supply using Eagle
2.) Etching the PCB using toner transfer method
3.) Soldering the components
4.) Placing the circuit in an enclosure

I'll provide resources that helped me in successfully making my own power supply, and mention the problems I had faced and how I managed to solve them. As this was done by a student the steps will not be as in-depth as some might expect but rather it shows how someone would accomplish such project as simple as possible with little experience or knowledge in electronics, therefore suggestions would be very much appreciated!



To start our journey let's have first our components list.
QTY.
PART NAME
RATING/PART CODE
1
Step-down Transformer
220Vpri, 12-0-12Vsec
6
Diode
1N4001
1
Capacitor
Electrolytic, 2200µF, 50V
2
Capacitor
Electrolytic, 22uF, 50V
1
Capacitor
Mylar, 0.1uF, 50V
1
Resistor
180Ω, 1/4w
1
Potentiometer
0-5kΩ
1
Adjustable Voltage Regulator (Positive)
LM317T
1 (pair)
Pole Terminal (red & black)

1
Switch (3-pin w/ LED)
250Vac; 10A
1
Heatsink

1
Potentiometer Knob

1
Enclosure




Now prepare your things and we'll design your power supply!

For those of you who would like to suggest a different component rating feel free to comment below, thanks!