How to convert an ATX (desktop computer) PSU into a bench power supply

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An illustration of a woman in an electronics lab.

When embarking on ESPHome projects involving devices like the ESP8266, ESP32, or RP2040, having a stable and appropriate power supply is crucial. While a single power source may suffice for your final project, a bench power supply can significantly enhance the prototyping phase. These devices, however, can be costly and bulky. Fortunately, an old ATX (Advanced Technology eXtended) computer power supply might be the perfect solution to your power needs.

A photograph of a black ATX power supply made by Corsair. The model name, VS350, is printed on one of the sides. There is a fan visible on the top of the united and cables exiting the rear.


The Advantages of Using ATX Power Supplies for ESPHome Projects

ATX power supplies are an excellent choice for ESP32, ESP8266, and RP2040 projects for various reasons. They're cost-effective, especially if purchased second-hand, and provide ample power. A built-in fan prevents overheating, and, when selected carefully, they come with all the necessary safety features to protect both you and your components. Importantly, these power supplies encase any live wires, exposing only low-voltage currents. Most crucially, they offer clean and stable 3.3V, 5V, and 12V outputs, exactly what your ESPHome projects require, with no extra hassle.

A photograph of the sticker on an ATX power supply showing the various output voltages.

Understanding the 24-Pin ATX Power Supply Connector

The secret to transforming an ATX power supply into a bench power supply is the 24-pin connector, typically attached to a computer's motherboard. It's advisable to leave other cables intact to avoid the risk of shorts. The 24-pin connector has various coloured wires indicating different voltages:

Among the other wires (purple, grey, brown, and green), the green wire is key to powering the ATX supply.

A photograph of a 24-pin ATX power supply connector.

Powering Up Your ATX Power Supply

You might wonder how to switch on an ATX power supply without connecting it to a motherboard. The solution is simple: create a bridge between the green wire and any black (ground) wire. Ensure that the power supply is switched off or unplugged before inserting a short wire between the two pins. Once connected, you can turn the ATX power supply on and off using the switch on the unit.

Esphome Atx Psu 06

Opting For a More Refined Approach

If you prefer a neater solution, consider investing in a board, such as the XH-M229, designed to connect to the 24-pin ATX connector. These boards offer added benefits like a power indicator LED, an on/off switch, and individual connectors for different voltage levels. They also have fuses to protect your boards in case of a power surge.

You can find 3D models online to further enhance your setup by covering exposed wires. The XH-M229 is available for purchase on various online platforms, including AliExpress, for less than $3.

With just a bit of tinkering, you can transform an old ATX power supply into a cost-effective and efficient bench power supply for your ESP projects, ensuring a stable development environment without breaking the bank.

A photograph of an XH-M229, a board designed to connect to the 24-pin ATX connector. On the board is a power indicator LED, an on/off switch, and individual connectors for different voltage levels.
A photograph of an ATX power supply in a 3D-printed cage. The cage features a handle for easy transport.

Warning: Risk of Electrical Hazards

Working with live wires can be extremely dangerous and carries the risk of electrical shock, fire, or other serious injuries. Home Assistant Guide is intended to provide general information and guidance, but it does not assume any responsibility for the accuracy, completeness, or suitability of the information provided.

It is important to note that electrical work should only be undertaken by individuals with the necessary knowledge, skills, and experience. If you are not familiar with electrical systems or unsure about the steps involved, it is strongly advised that you seek professional assistance or consult a qualified electrician.

By using the information provided in the Home Assistant Guide, you acknowledge and accept that you are solely responsible for any consequences or damages that may arise from your actions. The Home Assistant Guide cannot be held liable for any harm, injury, or damage to property resulting from your use of the information provided.

Always prioritize safety and exercise caution when working with live wires or any electrical components. It is essential to follow local electrical codes, regulations, and safety guidelines to minimize the risks associated with electrical work.

A portrait photo oif Liam Alexander Colman, the author, creator, and owner of Home Assistant Guide wearing a suit.

About Liam Alexander Colman

is an experienced Home Assistant user who has been utilizing the platform for a variety of projects over an extended period. His journey began with a Raspberry Pi, which quickly grew to three Raspberry Pis and eventually a full-fledged server. Liam's current operating system of choice is Unraid, with Home Assistant comfortably running in a Docker container.
With a deep understanding of the intricacies of Home Assistant, Liam has an impressive setup, consisting of various Zigbee devices, and seamless integrations with existing products such as his Android TV box. For those interested in learning more about Liam's experience with Home Assistant, he shares his insights on how he first started using the platform and his subsequent journey.

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