Picking a Power Supply: What to do with a PSU?

2023-12-01 | By Will Siffer

Why have a benchtop power supply? Do I really need one?

These are great questions. First off, a "Power Supply" is anything you have that can supply power to your projects. Whether it be a 5W USB power brick you got with your first MP3 player or a fancy adjustable lab-grade supply, they all essentially fit one purpose: to supply clean and consistent power.

Now, do you need a benchtop power supply? That answer is a complicated "m a y b e". When I started with hobby electronics, I used literally anything I could find as a power supply. From the old chargers to the chargers my family certainly were still using (sorry, Mom) I knew the exact power output of each, and I knew exactly which one I could borrow for my projects. Maybe this case sounds like you, and if so, I will link a product from DigiKey that I recently discovered that I wish I had back then.

The 1528-1448AD-ND at only $15 is perfect for just about every beginner! At 8W, it can't deliver a huge amount of power, but it gives access to voltages that can be hard to find from standard chargers (Ask me how many 5V 1A power supplies I hoarded over the years). Plus, this one comes with a bunch of different tips that allow you to plug it into any project or device you want, just be sure to be careful about what voltage you have set!

Picking a Power Supply What to do with a PSU?

Now, what if you want to really get into power supplies? What if you need even more power? What if you are trying to build the absolute greatest Arduino project of all time?

Well, my friend, this is where I direct you to my personal recommendation, the Korad KD series power supply. At $90 (at the time this article was written), I was surprised to see the host of features that it offered compared to lab power supplies costing 5-10 times more. Sure, maybe you only need 5W of power most of the time, and maybe the Adafruit power supply is enough for you 90% of the time. But one day (ask me how I know), someone might ask for the power supply you've been borrowing, and it was the only 5V 4A supply in the whole house, and now you can't finish your DigiKey ambassador project showcase because someone wanted to charge their Bluetooth speaker or rechargeable battery.

If that happened to you, it's time to look at a real power supply with real knobs and some really really cool features. Features like:

0-30V 0-5A adjustable output
Overcurrent protection
LED display
Setting Lock
0.5% + 20mV; 0.5% + 10mA accuracy
Constant voltage / constant current modes.

If you are anything like me, these features all sound like something you had when in the labs at university. Those supplies sometimes cost upwards of $500, and this is available from DigiKey for only $89.99!

Aside from the specs, this thing is QUIET. I have used probably 10 different bench supplies through my time at Purdue and in different maker stations, and this one is the only one that was so quiet that I forgot it was running. Maybe you find comfort in your PSU fan, but I found the quiet a nice change in my lab, especially when I was trying to diagnose issues with whining components.

Picking a Power Supply What to do with a PSU?

Above is the front view of the supply, and you'll notice just how many features are put right on the front for easy access for the user. The digital encoders used for the adjustment knobs are effortlessly smooth and have detents so you can feel the actual settings you are putting into the device and actually count the notches to be more precise. On top of that, the digital display is big enough that I can easily read it even from the other side of my bench or at an angle, something that you wouldn't think about until you realize you need it.

Finally, this power supply has an internal memory that allows for the device to turn back on to the same settings that were enabled on power off. This may seem small, but not having to plug in 5V 3A over and over because you keep turning off the supply will prove to be a very important feature once you try it.

That's pretty much it for this supply, but if you have any more questions or want to learn more about it, I encourage you to check out the datasheet on the product page and read more about the detailed specifications.

I also should mention that while this product was recommended to me by an engineer at DigiKey, ultimately this purchase was my own choice and with my own money. If you do decide to go with this supply, I encourage you to take advantage of DigiKey's great shipping policy of "on the way if ordered by 8 p.m. today."

Until next time, my name is Will, and as a DigiKey ambassador, I hope you learned something new today.