Low Noise Power Supply With Four ICs In Parallel

This low-noise power supply circuit is engineered to deliver a stable and clean 15V DC output by distributing the current load across multiple parallel voltage regulators. The process begins with an input stage utilizing a bridge regulator (BR1) and protective 1N4007 diodes (D1 and D2), alongside a robust network of capacitors (C1 through C17) designed to filter out ripple and high-frequency noise from the unregulated input source. Instead of relying on a single regulator, the core of this design employs four 78L15 voltage regulators (IC1 through IC4) connected in parallel. Placing linear regulators in parallel is a classic technique used to share the thermal and current load, which helps minimize internal thermal stress and significantly reduces the output noise spectral density compared to a single device operating near its limits. Resistors (R1 through R5) are utilized for biasing and current balancing across the parallel stages, ensuring that each 78L15 shares the load relatively evenly. Finally, LED1 serves as a visual power indicator, illuminating to confirm that the regulated 15V output rail is active and functioning properly.