PC Power Box with E fuse

Description: This circuit helps eliminate surplus small AC mains adapters from a desktop. It is a practical DC power supply box powered directly by the SMPS of a desktop PC. The output provides regulated, clean, and protected +12VDC. Additionally, a USB power port is included for charging portable devices such as cellphones and music players. To set it up, an unused 4-pin drive power connector from the system SMPS must be connected to this circuit. The +12V (yellow wire) from the SMPS is processed by a resettable electronic fuse consisting of components T1, T2, and T3, and is fed to the output terminal. The +12V is also down-converted to a stable +5V using a fixed three-pin regulator IC1. As a result, +12V (500-750mA max, depending on the characteristics of T2) and +5V (1A max) DC outputs are available for external use without affecting normal computer operations. Switch S1 serves as the power on/off and reset switch. Resistor R3 determines the maximum allowable output current, and T1 disables the output power switch T3 when the output load current exceeds the set limit.

This circuit design effectively repurposes the power supply capabilities of a desktop PC, providing an efficient means to power peripheral devices without the clutter of multiple adapters. The primary voltage of +12VDC is sourced from the computer's SMPS, which is typically designed to handle higher loads, ensuring that the additional load from this circuit does not interfere with the computer's operation.

The resettable electronic fuse, which is crucial for protecting the circuit, utilizes T1, T2, and T3 to monitor the output current. When the current exceeds the predetermined threshold set by resistor R3, T1 activates to cut off the output via T3, preventing potential damage to the circuit or connected devices. This feature enhances the reliability of the power supply by ensuring that it operates within safe limits.

The inclusion of a fixed three-pin regulator for the +5V output allows for stable power delivery to devices that require lower voltage, such as USB-powered gadgets. This dual voltage output capability makes the circuit versatile for various applications, from charging smartphones to powering small electronics.

The power switch S1 provides user control over the circuit, allowing for easy activation and deactivation, as well as a reset function to restore the circuit after a fault condition. This design not only optimizes space by reducing the number of external adapters but also promotes a cleaner and more organized working environment. Overall, this circuit is a practical solution for enhancing the utility of desktop power supplies while ensuring safe and regulated output for various electronic devices.This little circuit can assist you to get rid of all surplus tiny ac mains adaptors from your desktop. The circuit is nothing, however a sensible dc power box directly powered by the smps of your desktop pc.

Regulated, clean and guarded +12VDC is offered at the output of this unit. additionally, a USB power port is provided to re-charge transporta ble devices as well as cellphones and music players, etc. All you would like is to open your system box and connect an unused 4-pin drive power connector from the system smps to the current circuit. +12V (Yellow wire) from the smps is processed by a resettable electronic fuse designed around elements T1, T2 and T3 and feed to the output terminal.

equally the +12V is down converted to stable +5V by fastened three pin regulator IC1. As a result, +12V (500 -750mA max, based mostly on the electrical characteristics of T2 used) and +5V (1A max) DC provides are obtainable for external use, while not affecting the traditional computer functions. Switch S1 is that the power on/off cum reset switch. Resistor R3 sets the utmost allowable output current rate and T1 disables the output power switch T3, when output load current exceeds the set price.