Ultimate DC Power Supply Guide

Ultimate Guide to DC Power Supplies [PLUS 4 Top DC Power Supplies]

A good DC power supply is one of the most essential pieces of test equipment for any lab.  In this post we’ll cover everything you could need to know about DC power supplies.  We’ll go through what they are, the different types of power supplies, how to choose the best DC power supply for your application or lab, and finally our recommendations on the right power supply for various budgets and use-cases.

Read all the way through our ultimate guide to DC Power Supplies. Or you can jump straight to our recommendations for the best DC Power Supplies below!

Looking for an even more complete list of great DC Power Supply options? Check out comprehensive list of over 20 adjustable DC power supplies.

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What is a DC Benchtop Power Supply?

A good DC power supply can be the difference between a successful or failed electronics project.  But what is a DC power supply anyway?  A DC Power supply is a device that supplies electrical power to a circuit under test.  Lab supplies or benchtop power supplies convert AC power (from the wall outlet) to a stable DC voltage.  

There are fixed voltage power supplies that output a single voltage, but since the purpose of this article is prototyping and lab power supplies, we’ll focus the rest of the article to adjustable DC power supplies.

An adjustable DC power supply does exactly what it sounds like… it provides a variable DC output.  In addition to being able to adjust the output voltage, you can also adjust the current capacity as well.

Common Power Supply abbreviations

Before we dive any deeper into our Ultimate Guide to DC Power Supplies, there are a few abbreviations we should cover to avoid confusion.

  • CC – Constant Current mode
  • CV – Constant Voltage mode
  • PSSR – Power Supply Rejection Ratio
  • OCP – Over Current Protection
  • OPP – Over Power (Overload) Protection)
  • OTP – Over Temperature Protection
  • OVP – Over Voltage Protection
  • SCP – Short Circuit Protection
  • UVP – Under Voltage Protection

Check our related post where we define each of these acronyms in detail.

What are the different DC Benchtop Power Supply types?

There are two prevailing types of benchtop DC Power Supplies, Switched and Linear.  There are pros and cons for both types.

Switched DC Power Supply

Switched power supplies or switched mode power supplies (SMPS) use high frequency switching to achieve the desired output voltage.  SMPS offer high efficiency and compact designs.  Because switched power supplies are more efficient, they dissipate less heat than linear DC power supplies.  Switched mode power supplies are also typically less expensive than linear supplies.

The major drawback about switched power supplies is that they can inject a lot of noise into the device under test.  Shielding, decoupling, and other measures must be taken to ensure radiated and injected noise does not become an issue.  This is especially important for RF circuits (like Software Defined Radios) where power supply noise can show up as spurs and jitter in the RF output.

Linear DC Power Supply

Linear DC power supplies are the best choice when you need precise, stable, and regulated output voltage.  This type of power supply does not use switching elements to set the output voltage and they are regulated by feeding the output voltage back into the control loop to maintain a stable output.  

Linear power supplies are typically larger than switched power supplies.  In a lab or on a test bench, being a bit larger is usually not a big deal. There will be plenty of room next to your DMM, signal generator, and any other test equipment you may have.  A good benchtop linear DC power supply will offer superior load regulation and very low noise and ripple.  These factors make linear DC power supplies the perfect DC power supply for most applications.

How do I choose a DC Power Supply?

There are many factors and considerations that should be taken into account when trying to decide which DC power supply is the best choice for you and your needs.

Most of these factors are self explanatory, but are still important to consider when picking a DC power supply.  Below is a list of some of the key DC power supply specifications that should be reviewed before buying a new supply.

Max Output Voltage

This one is self explanatory, but it is vitally important.  Ensure that your supply will have enough headroom to power the various circuits you plan on testing.  Most DC power supplies will max out around 30 volts.  If you need to test circuits that require higher input voltage you may need a specialized high voltage power supply.

Max Output Current

Similar to maximum output voltage, maximum output current is also self explanatory.  It does take a bit more thinking and math to figure out how much current capacity you’ll likely need for the various circuits you’ll be testing.  One other thing you’ll need to consider is initial current draw when you first power on your circuits or devices.  There is often a spike in initial current draw.  These transients can often be subdued by adding decoupling caps.

Max Output Power

Rounding out the “maximum output” specs is max output power.  To figure out how much room you need here, you’ll have to do some math to figure out what the maximum power draw you circuits and devices will draw.  This should be a simple Ohm’s Law calculation: P = V*I.

Over Voltage Circuit Protection

An over voltage event can occur if certain elements of the power supply fail causing an unusually high voltage to appear at the output of the supply.  Modern DC power supplies are usually very reliable, but there is still a risk of an over-voltage failure.  This could be extremely problematic when testing expensive circuits.

Over Current Circuit Protection

Over current protection is similar to over voltage protection.  When the device under test draws more current than expected, the over current protections kick in.  Depending on the power supply, this could be a combination of both current limiting and shutting down the output of the power supply altogether.  Current limiting is usually an adjustable setting that configures the power supply such that no more current can be drawn than the set maximum value.  If the device under test begins to draw excess current, the power supply will switch from constant voltage mode to constant current mode.  This typically causes a “brown-out” condition such that the output voltage is less than the set value.  Again, think back to Ohm’s Law for this one.

Regulation

What is power supply regulation?  We thought you’d never ask!  There are two types of regulation that are important.  The first is load regulation.  As the loads on the power supply change a corresponding change in current supplied will be required to maintain a constant voltage output.  When these changes in current draw are large and sudden it can cause transients on the output.  Better load regulation, the more accurate and the smaller the voltage transients end up being.  

The second type of regulation is line regulation.  Changes in the AC line voltage at the input of the DC power supply can show up as noise or variations on the DC output.  Bench DC power supplies with good line regulation will be able to handle noisy AC signals over a wide input range, typically +/-10%.

Number of Outputs

One important consideration when picking a DC power supply is the number of independent outputs available.  For testing simple circuits, a single output supply is probably sufficient.  

But if you’re troubleshooting or testing complex circuits it may require multiple voltage rails to function probably.  Often final circuits will be powered from a single input and then in-circuit voltage regulation will be included to provide the various voltage rails.  When first bringing up a new circuit, it can be helpful to isolate these various rails and test them independently.  This is where having a DC power supply with multiple outputs comes in handy.

Control Interfaces

There are many different ways you can control a DC benchtop power supply.  There are the main interface controls to adjust the output voltage and current.  These can be through either analog control knobs that you physically turn.  Another style is digital controls with simple up-down buttons to adjust these parameters.  Deciding which is best for you really comes down to personal preference.

In addition to the main interface there are also many power supplies that have interfaces that allow you to control the power supply with a computer.  These interfaces include USB, LAN, RS232, and SCPI (to use LabView).  One thing to note with these computer interfaces, is that special drivers may need to be installed to make it function properly.  Make sure to read through the documentation from the manufacturer to ensure you set these interfaces up correctly.

4 Best DC Bench Power Supplies

We’ve researched dozens of DC benchtop power supplies to compile this list of 4 great DC power supplies.  We’ve considered several different use cases and compared many different factors such as price, features, reviews and ratings, etc.

A good power supply is the cornerstone of any lab or test bench, so without further ado, here are our recommendations.

Best DC Power Supply under $100

The TACKlife MDC02 packs a lot of punches into a pint-sized budget.  This compact DC power supply offers a whopping 10 amps of output current with a voltage range of up to 30V.  Both voltage and current can be adjusted with coarse and fine adjustments and dialed in to the precise values you’re looking for by reading the 4-digit displays.  

In terms of protection, the MDC02 has current limiting, over voltage protection, short circuit protection, over temp protection and more.  The integrated fan helps keep the heat dissipated and operates very quietly.

The MDC02 is known to be easy to use and with a price under $100, it is a perfect piece of test equipment for smaller labs, schools.  This one is a great hobbyist DC power supply as well.

The MDC02 is the #1 best seller on Amazon right now and they offer coupons and savings often, so make sure to click through to see the current price.

Honorable mention:  This was a close one to call… the MDC02 has some stiff competition!  Our 2nd favorite DC Power Supply under $100 is this model from Kungber.  It is a bit more expensive, but does offer higher output voltage up to 120V!

Best Single Output DC Power Supply

While it didn’t claim the top spot for the best DC power supply under $100, The Kungber 120V/3A supply did claim our top spot for the best single output DC power supply.

The Kungber DC 120V 3A DC Power Supply has got everything you’d expect from a modern DC power supply, good circuit protections, good regulation, high output voltage, and high output current.  It also has coarse and fine adjustments to dial in the exact values on the 4-digit display.  One other cool feature is a USB output right on the front of the Kungber supply.  This could come in handy if you’re using it to power a portable device under test or just to charge your phone while you’re goofing off working hard in the lab.

Overall, the Kungber offers great value in an attractive enclosure that would look at home on any lab bench.

Best Multi Output DC Power Supply

Our top pick for the best DC Power Supply with multiple outputs is the Rigol DP832 Triple Output Power Supply.  Rigol is a well respected brand that offers loads of great test equipment for really competitive prices.  The DP832 is no exception.

The Rigol DP832 has three outputs that can be switched between 30V/3A and 5V/3A.  The maximum output power is an impressive 195W!  The construction and interface of this unit is top notch and offers an intuitive design.  In addition to the front panel controls, the Rigol DP832 Supply can also be remotely controlled via USB, LAN, RS232 or even GPIB.

When powering complex circuits with multiple voltage rails, the Rigol DP832 DC Supply is a great choice for the price!  The stock levels on these units fluctuate constantly, so be sure to check the link below to make sure they are in stock.

Check Rigol DP832 stock and price.

Honorable Mention: Siglent SPD3303X-E Triple Output Power Supply

The Siglent SPD3303X-E is another great supply with three independent and isolated DC outputs. The primary reason the Rigol DP832 edged past the Siglent unit is due to the software upgradable options that are offered with the Rigol supply. These will cost extra but increase the accuracy and functionality of an already great power supply.

Best DIY DC Power Supply Kit

Here’s a special addition for the adventurous DIYers… the LM317 kit is a build your own supply that you can pick up for less than $20!  You’re not going to be setting any accuracy or reliability records with this thing, but for the price it will get the job done… assuming that job is powering simple prototype circuits.  The output voltage is adjustable from 1.25V up to 12V.  Be patient if you decide to give the LM317 DC supply a try.  The instructions are pitiful and hard to follow.  A basic understanding of rectifier and regulator circuits would come in handy.  The final build quality turns out pretty darn good for something less than $20 and the components included are of reasonably good quality.

Must have DC Power Supply Accessories

One of the most frustrating things that can happen in a lab is getting your circuit all finished and ready to be tested only to find empty lead and probe racks.  If you’re upgrading your lab’s power supply, its probably a good time to pick up some new test leads.  Here are some of our favorites.

Sumnacon Banana Plug to Minigrabber leads

Sumnacon Banana Plug to Minigrabber lead - 5 colors, red, yellow, green, black, blue
Sumnacon Banana Plug to Minigrabber leads

Sumnacon Banana Plug to Alligator Clip leads

Sumnacon Banana Plug to Alligator Clip lead - 5 colors, red, yellow, green, black, blue
Sumnacon Banana Plug to Alligator Clip leads

Sumnacon Banana Plug to Banana Plug leads

Sumnacon Banana Plug to Banana Plug lead - 5 colors, red, yellow, green, black, blue
Sumnacon Banana plug to Banana plug leads

Fieldpiece Banana Plug to Straight Probe Tip

Fieldpiece Banana Plug to Straight Probe Tips - 1 red and 1 black
Fieldpiece Banana Plug to Straight Probe Tips

2 comments

  1. Very interesting article and recommendations… It would be more useful to be able to download the article and its recommendations as a PDF.

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