An Easy Way to Power Your Projects


I have a few power supplies I picked up cheap from a closing RadioShack – a 3.3V, a 6V, and 9V, and was pretty disappointed when I figured out that an LED strip I had required 12V. All these different power supplies take up a lot of space and can be unsightly. I tried to find a better solution.


And I found it – a Compact Switching Power Supply – Selectable Output 3-12VDC. Adafruit sells these awesome power supplies that allow you to take advantage of six different voltage settings for your projects.

The key is that it has a selectable output, not to be confused with a regular Switching Power Supply, which switches itself at low currents to make the adapter more efficient.


It comes with a handful of male plugs, including the 2.1mm which can plug directly into boards that offer the plug. So I bought a few stand-alone jacks for future projects. With one of the jacks, I created this nifty breadboard power unit. Now I’m ready for any breadboard projects (under 12V)!

Most Arduino boards can be powered over a USB cable or an external power source, such as a battery or AC-to-DC power adapter.  Some boards include a 2.1mm center positive male power jack, but power can also be supplied to the Vin and GND (ground) pins.

Most common 5 volt microcontroller boards recommend 7-12 volts (6-20 volts allowable). This is misleading, as the USB connection from your computer or a standard phone charging USB adapter all supply 5V, and the Arduino will work just fine on them. This is because the USB bypasses the voltage regulator on the Arduino, which may drop the voltage below 5V. To bypass the regulator yourself, you can connect a regulated 5V power source directly to the 5V and GND pins, instead of using Vin, which should be >5V.

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