Basic Power Supply Circuit & Theory

Introduction: Basic Power Supply Circuit & Theory

In this project I will show you how to make your own power supply using basic components. I will cover the basic theory on Transformers, rectification smoothing and regulation.

Step 1: Transformation

The voltage in the UK and European countries is 230v. This voltage is too high to use for many applications so it needs to be reduced. You use a transformer to reduce the voltage. I have included the input and output wave for the transformer. In this case the transformer reduces the 240V down to 40V.

Step 2: Rectification

Once you have reduced your AC voltage by the use of a transformer you will be left with a lower voltage AC power supply. Most circuits use DC (direct current) in order to get DC from an AC supply you will need to rectify it. I have included a example of the waves so you can better understand what it looks like.

Rectification is done using diodes. You can use a single diode rectifier or a full bridge rectifier. A single diode rectifier is half wave rectification this means that it will only have the positive parts of wave but it will be missing the negative parts of the wave.

Full wave rectification uses 4 diodes and will 'flip' the negative part of the wave so you will end up with a positive wave with no gaps between the original positive wave like the half wave rectifier would.

For half wave rectification you use 1 diode and for the full wave rectifier you use 4 diodes. The configuration for the half bridge and full bridge rectifier are shown below.

Step 3: Smoothing

Now that you have you have rectified your AC it now needs to be smoothed. Smoothing refers to taking the rectified wave and holding the output to the highest point of the wave.

To smooth a rectified AC signal you use a capacitor. I have included a circuit diagram to show how you would place the capacitor in the circuit.

Step 4: Regulation

Now that you have a DC voltage it needs to be stepped down to a precise voltage. You can use a regulator to reduce a DC voltage. Voltage regulators can come in many variants from fixed voltage to variable voltage.

Step 5: Final Circuit

Now just combine all the parts and you will have a DC power supply.

Step 6: Acknowledgement

I thank PCBWay & LCSC Electronics for the partnership.

PCBWay is a cheap and reliable service where you can get your PCBs manufactured. All the PCBs are high quality and the engineers are very helpful. Sign up today and get a $5 welcome bonus. Check out their Gift shop and Gerber viewer.

LCSC Electronics Is China's leading Electronic Components Distributor. LCSC sells a wide variety of high quality electronic components at low prices. With over 150, 000 parts in stock they should have the components you need for your next project. Sign up today and get $8 off on your first or

Step 7: Website

Check out more of my other projects on my website.

Be the First to Share


    • The 1000th Contest

      The 1000th Contest
    • Battery Powered Contest

      Battery Powered Contest
    • Hand Tools Only Challenge

      Hand Tools Only Challenge