DIY Breadboard Power Supply Circuit on PCB

This DIY breadboard power supply circuit is designed to take an incoming external power source via a DC Barrel Jack and step it down into stable, usable voltage rails for prototyping. The foundational architecture relies on two distinct voltage regulation stages utilizing an LM317 Variable Voltage Regulator and a fixed 7805 Regulator. The 7805 regulator takes the input voltage and steps it down to a steady, fixed 5V output, which is standard for many digital logic circuits and microcontrollers. Simultaneously, the LM317 variable regulator allows for adjustable output voltages—such as 3.3V—by utilizing a specific resistor network consisting of a 330 ohm resistor and a 560 ohm resistor connected to its adjustment pin to set the output scaling. To ensure stability and prevent high-frequency oscillations or voltage spikes inherent in linear regulation, 0.1uF and 1uF capacitors are placed at the input and output terminals of the regulators for decoupling and filtering noise. A current-limiting resistor is paired with an indicator LED to provide visual confirmation that power is successfully flowing through the board. Finally, Male Bergstik/Header pins are integrated onto the custom PCB, allowing the entire module to snap directly and securely into the power rails of a standard solderless breadboard.