12V/5V Power Supply Hookup Guide

Contributors: bboyho
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The 12V/5V (2A) power supply is great for powering a microcontroller and an LEDs. In this tutorial, we will replace the power supply's molex connector with two male barrel jacks adapters.

Power Supply - 12V/5V (2A)

Power Supply - 12V/5V (2A)


Required Materials

To follow along with this tutorial, you will need the following materials. You may not need everything though depending on what you have. Add it to your cart, read through the guide, and adjust the cart as necessary. The kit on the left is the easiest to connect. The wishlist to the right is for those that are interested in hacking the power supply.

SparkFun ATX Power Connector Breakout Kit - 12V/5V (4-pin)

6 Retired


You will need a soldering iron, solder, general soldering accessories, and the following tools.

Digital Multimeter - Basic

Digital Multimeter - Basic

Hook-Up Wire - Assortment (Solid Core, 22 AWG)

Hook-Up Wire - Assortment (Solid Core, 22 AWG)

Solder Lead Free - 100-gram Spool

Solder Lead Free - 100-gram Spool

Flush Cutters - Xcelite

Flush Cutters - Xcelite

Diagonal Cutters

Diagonal Cutters


Weller WLC100 Soldering Station

2 Retired

Wire Strippers - 22-30AWG

4 Retired

Suggested Reading

If you aren’t familiar with the following concepts, we recommend checking out these tutorials before continuing.

How to Solder: Through-Hole Soldering

This tutorial covers everything you need to know about through-hole soldering.

Connector Basics

Connectors are a major source of confusion for people just beginning electronics. The number of different options, terms, and names of connectors can make selecting one, or finding the one you need, daunting. This article will help you get a jump on the world of connectors.

How to Power a Project

A tutorial to help figure out the power requirements of your project.

Working with Wire

How to strip, crimp, and work with wire.

How to Use a Multimeter

Learn the basics of using a multimeter to measure continuity, voltage, resistance and current.

Hardware Overview

The power supply's pinout is shown below. The connector's molding should have numbers associated with the output to help identify the connection. You will also notice that the connector is polarized with the two chamfered corners.

Molex Connector Pinout with Labels

Pinout Table

The following table describes the ATX connector's pinout and what color the wire may look like.

ATX Pinout (4-Pin) 12V/5V Power Supply Notes
1 +12V "Red"
2 N/C May Not Be Not Connected
3 GND "Yellow"
4 +5V "Black (or White)"

Hardware Hookup

Breakout Board

To easily connect to the 4-pin connector, we recommend using the ATX power connector (4-pin). For more information, check out the tutorial.

ATX Power Connector (4-Pin) Breakout Hookup Guide

October 10, 2019

Do you need to power a project with 12V and 5V from one wall adapter? The ATX power connector breaks out the standard 4-pin computer peripheral port for your 12V and 5V devices!

Hacking the 4-Pin Connector

Otherwise, you can modify the cable and use a polarized connector of your choice. This requires more time and effort. The following images use the older 12V/5V power supply so the wires may be different depending on the manufacturer. Cut the cable about 1-2 inches from the 4-pin ATX connector.

Cut cable

Cut into sheath with the flush cutter. Pull it back just enough so that you have enough room to work with the wires. Be careful not to cut yourself!

Cut Sheath

Strip the power supply's three wires. The wires are stranded so feel free to tin the wires by adding solder to the tips.

Tin Wires

Then cut and strip a piece of hookup wire. Solder it to the ground wire.

Refrence Ground Wire

Braid the wire and insert into a barrel jack connector. Secure the wires in the screw terminal with a Phillips head. Feel free to add some heat shrink or electrical tape to the connection at this point.

Tighten Screw Terminals

Test the Output

If you modified the cable with barrel jack connectors, power the power supply and test with a multimeter to verify the voltages. Usually power supplies are center positive so make sure that the wires were inserted correctly. Adjust as a necessary for your system.

Test outputs

Label the Output

If you modified the cable with barrel jack connectors, we recommend that you clearly label the barrel jack connector's voltage relative to the output using a Sharpie. Feel free to add an additional barrel jack when not in use.

Label Barrel Jacks

Power Your Circuit!

Connect the power supply to your circuit and power it up! I personally use the power supply as a tool for basic testing. Usually the 12V side is connected to an Arduino's barrel jack. The 5V output is used for more power hungry loads such as the the RGB LED Matrix or a few meters of addressable (WS2812B, APA102, etc) LEDs.

RGB LED Matrix 32x64 Powered with the 12V/5V (2A) Power supply

Arduino Mega 2560 and 32x64 RGB LED Matrix Powered by the 12V/5V Power Supply


Certain power supplies have a lot of noise. While a 12V/5V power supply works great with a microcontroller and a LED strip, it may not work as well when you attach a capacitive touch sensor to the system depending on the manufacturer. Certain dual-voltage power supplies can lack the proper filtering and cause the capacitive touch potentiometer to have a lot of latency. You can try to add additional circuitry to fix it if the current power supply has a lot of noise.

You should not see this issue with the newer 12V/5V power supply (TOL-15664). It is more reliable than our previous version. Otherwise, you can also try to use two separate power supplies or a more robust power supply such as a Meanwell.

PWM Lighting Controller

Example PWM Lighting Controller from the Touch Potentiometer Hookup Guide

Resources and Going Further

Now that you've successfully got your 12V/5V power supply up and running, it's time to incorporate it into your own project!

For more information, check out the resources below:

Need some inspiration for your next project? Check out some of these related tutorials that uses the 12V/5V (2A) power supply.

RGB Panel Hookup Guide

Make bright, colorful displays using the 32x16, 32x32, and 32x64 RGB LED matrix panels. This hookup guide shows how to hook up these panels and control them with an Arduino.

Large Digit Driver Hookup Guide

Getting started guide for the Large Digit display driver board. This tutorial explains how to solder the module (backpack) onto the back of the large 7-segment LED display and run example code from an Arduino.

How to Build a Remote Kill Switch

Learn how to build a wireless controller to kill power when things go... sentient.

Building a Safe Cracking Robot

How to crack an unknown safe in under an hour.

Or check out some of these blog posts about power supplies