Low Power PCB Design for Capacitor-based Uninterruptible Power Supply (UPS)

A small and effective uninterruptible power supply (UPS) circuit to provide a steady 5V output for low-power applications. The circuit makes use of BF245 JFET transistors (Q1 and Q2) to switch automatically, a 1N4007 diode for rectification, and capacitors for voltage storage and stabilization. The 4700μF capacitor (C1) serves as an energy backup, and C2 (1μF) smoothes voltage variations. Resistors R1 (10KΩ), R2 (1.8KΩ), and R3 (1MΩ) are essential to bias and stabilize the circuit for proper transistor operation. Output voltage is controlled by the 500KΩ load resistor (RL) and held at a constant 5V. The PCB design must make trace routing, thermal, and component placement optimized for efficient operation with minimal interference. Designed for uninterrupted power supply, this circuit offers smooth switching between main power and stored power, thus being ideal for sensitive electronic applications wherein momentary power interruption should be alleviated.