How to Design a Power Supply Circuit PCB (Step-by-Step)

BeginnerPCB Wizard

Almost every electronics project needs clean, regulated DC power. This tutorial walks through designing a basic regulated power supply PCB — converting mains AC into a steady DC voltage your circuits can safely run on.

Components You'll Need

Step-down Transformer (e.g., 230V to 12V)
Bridge Rectifier (or 4x 1N4007 diodes)
Filter Capacitor (1000µF, 25V electrolytic)
Voltage Regulator IC (7805 for 5V output)
Output Capacitor (100nF ceramic + 10µF electrolytic)
LED + 220Ω resistor (power indicator)
Input/Output terminal blocks

How the Circuit Works

1. Transformer steps mains voltage down to a safer, lower AC voltage
2. Bridge rectifier converts that AC into pulsating DC
3. Filter capacitor smooths the pulsing DC into a steadier voltage
4. Voltage regulator (7805) locks the output to a clean, fixed 5V regardless of small input fluctuations
5. Output capacitors filter out any remaining noise before the power reaches your circuit

Designing the PCB in PCB Wizard

1. Place the Bridge Rectifier and Filter Capacitor First

These are your highest-current components — position them close together near where the transformer wires will connect, to keep the AC-to-DC conversion path short.

2. Place the 7805 Regulator

The 7805 has three pins: Input, Ground, Output. Leave space around it — this component can run warm under load, and in a real build you may want to add a heatsink.

3. Route Power Tracks Wider Than Signal Tracks

The main input/output power path carries more current than any signal line — route it wider (in PCB Wizard, this is a track-width setting) to avoid excess heating.

Tip: Add a power LED with its current-limiting resistor near the output terminal — it is a small addition that makes testing much faster, since you can tell instantly if the supply is live.

4. Keep the AC Input Side Separated From the DC Output Side

Route your layout so the transformer/AC input tracks stay physically apart from the regulated DC output section. This isn't just neat practice — it reduces the chance of AC noise coupling into your clean DC rail.

Watch out: Double-check the 7805's pin order before placing it — Input, Ground, and Output are not symmetrical, and reversing them will not damage the board, but the circuit will not work until corrected.

Testing Your Board

Before connecting anything else, power the finished board alone and measure the output with a multimeter — you should read a steady 5V (or whatever regulator voltage you used) with no other load connected. Only once that's confirmed should you connect it to power an actual project circuit.