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Everything You Need To Know To Find The Best Interchangeable Plug Power Adapter

Author: Jesse

Apr. 14, 2025

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How to Select the Right External Power Adapter - Astrodyne TDI

Whether you need an external power adapter for a new product or as a replacement for an existing product, finding the right one can be tricky. There are a few details that are important to consider when selecting an external power adapter, including its power and voltage specifications, which if selected appropriately will prevent certain issues that can lead to product failure.

How do you choose an external power adapter? This guide covers several parameters to consider when selecting the right external power adapter for your device or system.

If you want to learn more, please visit our website.

What Are External Power Adapters?

External power adapters are a type of power supply that plug into a wall outlet and convert alternating current (AC) to a direct current (DC) that powers certain electronic devices. They may also be called AC adapters, AC-DC adapters, AC-DC converters, DC power supplies, external adapter power supplies, or simply power adapters. 

External power adapters are used in a variety of applications, from sophisticated medical devices like circulatory pumps, ventilators, dialysis equipment, and telemedicine carts, to commercial or industrial manufacturing equipment like barcode scanners, weighing scales, and assembly line monitors, to consumer devices like laptop computers, computer monitors and printers. 

You can think of an external power adapter as a “black box,” with the AC input on one side and the DC output on the other side. It is typically offered in one of two styles, depending on the application requirements: wall mount or desktop. A desktop power adapter is designed to sit on the floor or a desktop and is typically shaped like a brick and has a power cord sticking out of one or opposite ends. A wall-mount power adapter has only an output cord at one end and includes power blades that protrude from the body of its case to plug directly into an AC wall socket.

A wall mount power adapter eliminates the need for an AC input cord but is limited to being used with the style of AC wall socket specific to a particular country unless it has an option for interchangeable AC plugs. A desktop adapter may include a captive AC cord and plug, which would have a similar limitation to a wall mount adapter, but most use a standard AC inlet that can accept different AC cords with plugs specific to whichever country in which they will be used. 

Most external power adapters available today – both wall-mount and desktop – can accept a “universal” AC input voltage of 90 to 264 volts AC (VAC). This voltage range will support the vast majority of countries, with the need to match only the AC input cord or wall plugs for a specific country; the power adapter itself can be used universally. This feature results in supply chain efficiency, and may even result in reduced product costs by leveraging volume manufacturing.

The main reasons for a product engineer to use an external power adapter over an internal (“embedded”) power supply in their system are size reduction and ease of replacement. By using an external adapter, the product itself can be made smaller (although the power adapter itself adds size back to the complete system – no free lunches!) And an external adapter can easily be replaced by a user, without the need for support from an experienced technician. The user simply needs to ensure that they have selected an adapter that will work with their product.

How Do I Know Which External Adapter to Use?

When choosing an external power adapter for any application, one must consider a few critical parameters to ensure that the adapter will perform effectively and safely:

AC Input Voltage

As previously mentioned, most external power adapters available today can accept a “universal” 90 to 264 VAC input voltage, which can support the vast majority of worldwide applications. In North America, domestic outlets supply 110-120 VAC. In Europe, they supply 220-240 VAC. Portable medical applications may require an AC input voltage as low as 85 VAC, and lighting applications often use a 277-205 VAC source. Note that some industrial and many infrastructure applications use a much higher AC voltage range, which would require different types of power converters.

DC Output Voltage

A product or device that is powered by an external power adapter requires a particular voltage, usually in a range from as low as 3.3 VDC to as high as 56 VDC, to operate correctly. An adapter must be selected with the appropriate matching DC output voltage, which will be marked on its label. Most adapters provide a single DC output, but some adapters provide two or three different output voltages (each with its power rating.) A selection of adapter models with standard output voltage increments are generally available, and custom models with non-standard output voltages can be provided from certain vendors, including Astrodyne TDI, as well.

Power Rating

One of the most important external power adapter specifications that is often overlooked is its output power rating. An adapter’s power rating is marked on its label, typically specified in Watts (W). This rating depicts the maximum power that can be reliably delivered from the adapter to the product being powered. The power rating of the adapter must always be equal to or greater than the power that will be consumed by the product being powered. Otherwise, undesirable results, such as reduced adapter lifetime, limited performance, or complete loss of functionality could occur.

It is important to note that an adapter's power rating is generally defined for use at room temperature. Operation at temperatures well above that - typically above 40-50 deg C (105 to 120 deg F) – may not support the full power rating. The datasheet for the adapter should include a power derate over-temperature graph, which details the maximum power that can be delivered at given operating temperatures.

Efficiency Rating

Recent commercial and industry regulations mandate minimum levels of power efficiency for external adapter power supplies. For example, in the United States, the Department of Energy instituted a requirement that beginning in , all external adapter power supplies introduced into the U.S. market (with a few exceptions, including adapters used to power FDA-approved medical devices) must meet Level VI efficiency requirements. Similar mandates exist in the European Union. 

Adapters that meet these U.S. requirements are usually marked with the roman numeral VI enclosed in a circle. Older designs marked with roman numerals IV or V are no longer approved for U.S. market introduction. Many external power adapter manufacturers still provide solutions that do not meet the new requirements, so it is important to confirm what is needed for a particular application and whether the power supply being considered conforms to the applicable mandates.

Connectors

Connectors that are appropriate for each application will need to be selected for both the AC input and the DC output of the external adapter power supply. For the AC input, a common practice for desktop adapters is to use an IEC320-C14 or -C8 inlet, to which standard power cords with wall socket plug ends suitable for use in specific countries can be separately attached. Alternately, a captive AC input cord may be used, with a wall socket plug specific to a particular country or country. Wall mount adapters will require fixed blades specific to the country of use, or a selection of interchangeable blades that can support a variety of countries.

A great diversity of DC power connectors are required by the innumerable applications that can use external power adapters. System designers tend to make their own decisions on what connector they prefer, and it is usually straightforward to accommodate almost most requests. The most common standard DC connectors are female barrel plugs, which are two-conductor (output voltage and return) solutions that are also available in a variety of sizes.

The four main parameters that need to be specified for a barrel plug are inner diameter, outer diameter, barrel length, and polarity - whether the center contact is the output voltage (standard configuration) or the return. Other barrel plug features include whether there is a “locking” mechanism, such as a screw-on collet, to secure the plug to the jack on the device being powered. Other types of common connectors include multi-pin DINs and “Molex” style pin/socket receptacles.

Safety Certifications

Finally, external power adapters will require safety certifications specific to the applications and countries in which they will be used. There are different certification standards for medical applications than there are for commercial/industrial applications, and each country or region requires its certifications as well. Astrodyne TDI offers adapters with either medical or safety certifications (and sometimes both), for standard use in the U.S., Canada, and the European Union. Additional country safety certifications, and certification to other standards, can be obtained upon request.

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The Best Travel Plug Adapter of | Reviews by Wirecutter

Do you travel? Are you going to travel sometime in the (near or far) future? Do you want to be able to charge or use electronic devices in a different country?

If so, you’re probably going to need a travel plug adapter. There’s a variety of different outlet types around the world, not to mention different voltages and frequencies, so you can’t expect your charger to just plug in and work wherever you’re headed.

Sure, Canada, Mexico, Japan, and many other countries use the same small pair of prongs as the US, but places like continental Europe, the UK, Australia, India, Russia, and pretty much everywhere else do not.

You have two main choices when it comes to travel plug adapters: the universal-style travel adapters (that’s one device with multiple sets of prongs that you extend and retract) and smaller, individual plug adapters that usually come in sets. Both have pros and cons.

Should you get a universal travel adapter or a simple plug adapter?

Universal travel adapters are for the person who wants one handy adapter that will work in just about every country. You can keep it next to your passport and toss it in your luggage when you’re packing. The ones we considered have USB ports, so you don’t need to worry about bringing a separate charger for anything that charges via USB (think phones and noise-cancelling headphones). However, these are bulky, they have parts that can break, and even the best will take longer to charge your or tablet than will a good USB wall charger.

The alternative is small and simple plug adapters. These attach to the prongs of your current USB charger (whether it’s a multiport one or the charger that came with your device) to allow them to fit into a foreign outlet. These can work because nearly every modern charger can adjust to the available voltage in pretty much every country, as long as you can adapt the prongs to fit in the outlet. (More on this in Do you need a voltage converter?)

These are great for people who already have a multiport USB charger they like and don’t want to deal with the additional bulk of a universal travel adapter. Also, these are necessary if you’re traveling to a country that has outlets incompatible with any of the four types included in a universal adapter (which, as that sentence reveals, aren’t actually universal).

The choice between universal travel adapters and individual plug adapters ultimately comes down to personal preference. Both types work, and different people will like or dislike each. If you’re not sure which will be best for you, read each section here closely.

Here’s the big caveat: If you’re planning on bringing something with you that has a motor, a heating element, or a single power cord that leads directly from the plug to the device (i.e. there’s no power brick or wall wart), it almost certainly won’t work with a travel plug adapter. Most people will only need one of the adapter choices we recommend, but very occasionally there’s a piece of gear that needs a voltage converter. For more on that topic, also check out the voltage converters section below.

Where in the world will your travel plug adapter work?

All universal travel adapters have four different sets of prongs, which cover most countries most Americans tend to travel to. First is the big, wide-blade UK-style plug (often designated "Type G”). This will work in places like the UK, obviously, and also Ireland, Hong Kong, and some other parts of Asia and the Middle East.

Next is the round Europe-style plug, aka the Europlug (Type C). However, this is where we run into complications. This plug should work in most of Europe—it was designed, in fact, to fit into a wide range of European outlet types. For instance, parts of Italy, Switzerland, and Denmark each use different plugs from one another. Should this double-round one work in those locations? Yes. Will it? Hard to say. I’ve stayed in places where my Europlug didn’t work, yet it did in the hostel before and the hotel after—all within the same small region of a country. With any luck, if this happens to you, the place you’re staying will have a power strip that will let you plug in, though there’s no guarantee of that.

Third is the angled small-blade style (Type I) found in Australia, New Zealand, Fiji and other parts of Oceania, and a few other areas. Some universal adapters have one set of blades for this and the US style—you just manually rotate the blades into the correct position depending on where you are. In our testing, we had no trouble getting them to work.

The last, the small US-style blades (Type A or B), mean you could use our picks to visit the US and other countries that have the same plugs—if, that is, you’re reading this from outside the US.

What are the places not covered by these four styles? Some parts of Brazil, South Africa, India, and more. I’ve stayed in parts of Italy, for example, that should have Europlugs but only had something called Type L. I’ve stayed in houses in Brazil that had Type N, but the Europlug fit enough to work. In others, it wouldn’t.

To find out which plugs you might need while traveling, refer to the excellent Wikipedia article called Mains electricity by country that shows pictures of (almost) all the possible plugs and outlets, along with a list of the world’s countries and (almost all of) the style or styles they use. This is invaluable information to check before you leave. If multiple plug types are listed for a specific country and you’re staying in an older building, you should probably assume its outlets will require whatever plug isn’t on a universal travel adapter, since these only have the most common, newer varieties of plugs.

You will get efficient and thoughtful service from Teng Da Xing.

Which brings us to perhaps the most important fact: Getting your gear to work in different countries isn’t quite as simple as it should be, and there’s no single solution that’s guaranteed to work for everyone.

Our picks should work for you, but you may have some random piece of equipment, or be traveling to some country, for which our “good for most” picks just won’t work. (Case in point: One Wirecutter editor visited Iceland a few years back. The house she stayed in had outlets unlike anything on Wikipedia’s chart, and the plug adapters she’d used elsewhere in Reykjavik didn’t fit at all. It turns out the mystery sockets belonged to an obscure Italian system from the s that was popular in Iceland for a time. Luckily, the hosts had power strips in the house that her adapters fit into.)

We’ll try to mention such potential caveats when we can, but the world is a big place, and when it comes to electricity and wall outlets, there’s a lot of variation. That’s important to keep in mind.

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Top pick

With four plugs that will work in most countries, plus faster-charging USB ports (and more of them) than its competitors, this adapter is the best all-around choice.

Buying Options

$24 $19 from Amazon (3 UCB-C, 2 USB-A port model)

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While all the universal travel adapters we tested included the same three types of plugs (plus the familiar US-style one), they differed in how many USB ports each had and how quickly they could charge—and that’s where the Epicka Universal Travel Adapter excelled. It has five USB ports: four of the standard USB-A size and one USB-C. These will let you charge, say, three phones, two tablets, and—via the adapter’s main plug—a camera battery that has its own wall charger, all at once.

In addition, and just as important, is the maximum power output: 5.6 amps. This was the highest of all the adapters we considered, which means you can charge more of your devices at higher speeds before hitting the max output.

Keep in mind that the maximum output per USB-A port is 2.4 amps, the max on the USB-C port is 3 amps, and if you’re using all five ports you won’t be able to charge every connected device at full speed—it’ll only give you that 5.6 amp output in total. The output is still far lower than what you can get from a decent USB charger combined with our pick for a simple plug adapter (more on that in the plug adapter section, below), but it’s significantly better than most universal travel adapters, which often max out under 3 amps total.

The Epicka has three sliders on one side, with a button on the other to lock/unlock your chosen plug in place. This arrangement feels more secure than the semi-locking or slide-locking system that some other universals use. However, this is plastic-on-plastic, so don’t expect a tank. As these things go, the Epicka feels sturdy. The US and Australia share a pair of prongs—you twist the prongs manually to set them up for an angled Australia-style outlet.

The four regular USB plugs are all on one side, which is tidier than the “flailing gibbon” look of some other universal adapters.

The above details were what put the Epicka at the top of our list, but the adapter has a few other features that are the cherry on top, so to speak. For instance, it comes with a small nylon case and a USB cable with a split end, so it works with either Micro-USB or Lightning devices. While the adapter has an LED to show you it’s working, the glow isn’t so bright as to be a distraction at night.

One last note. There are multiple Epicka universal adapters, and even Epicka can’t keep the names straight. We’ve seen this one called, variously, Universal Travel Adapter, International Travel Adapter, Travel Adapter-2, Universal USB Travel Power Adapter (), and even Universal Travel Adapter One Worldwide International Wall Charger AC Plug Adaptor with 5.6A Smart Power 3.0A USB Type-C for USA EU UK AUS Cell Tablet Laptop (Grey). Best to follow the link above. Also, you may find another company selling a twin of this. The Epicka has the most reviews and offers free shipping with Prime. The other options we saw have few or no reviews, or charge outrageous shipping costs.

Flaws but not dealbreakers

As with all of these adapters, I wouldn’t expect the Epicka to last forever. Given its locking design and case, it’s probably going to last longer than many others, but all of these are almost entirely inexpensive plastic devices. Just something to keep in mind.

While the prongs themselves felt secure, and being able to lock them into place was nice, it’s entirely possible that the size and weight of the adapter, plus whatever you’ve plugged into it, could pull it out of an outlet. That is, unfortunately, a risk with every universal adapter.

Another risk with any universal adapter—as we mentioned above—is that it’s not going to work where you’re headed. Epicka claims it will work in 150 countries, but there are more than 200 countries (the exact number is harder to pin down than you might realize). And even in each of those 150 countries, there’s no guarantee that the adapter will work in every outlet in every building. Plug adapters are a somewhat safer bet to work specifically where you’re going, but they have their own downsides, which we’ll discuss below.

Also, while the Epicka is a little smaller than some of the others we tested, all universal adapters are much bulkier than plug adapters. As someone who has spent most of the past several years traveling, I feel plug adapters are far easier and less annoying to deal with. This is largely why we have two recommendations for that category.

Top pick

Individually, these tiny plug adapters are smaller, lighter, and cheaper than any universal travel adapter. To juice up multiple devices, though, you’d need a separate multiport charger too.

Buying Options

The Ceptics Plug Adapter set combines everything we were looking for in plug adapters: small size, solid build quality, and—well, small size is really the thing here. Each adapter is no larger than it needs to be to fit over the American-style prongs of your charger. The plastic feels solid and not flimsy. Each adapter has the region or countries it should be used in written on the side. The five plugs in the set are the same four as you’ll find on the universal adapters recommended above, plus the thicker, round European-style prongs used in parts of France, parts of Asia, and elsewhere.

Though the set comes with a small case, you probably wouldn’t be traveling with the entire set very often. Instead, you’d pack just the specific adapter or adapters you’d be using on each trip. These are for the person who wants to travel as light and as simply as possible. I myself, and my friends who travel frequently, swear by these small, inexpensive adapters. Also, if you have a USB multiport charger you like or a charger that’s especially fast, you can use that charger with just a tiny, almost weightless plug at the end.

However, plug adapters aren’t for everyone, and that’s why they’re not our main pick. For one thing, if you don’t already own a multiport USB wall charger, you’ll still have to get one if you don’t want to carry a charger for each device. Also, depending on what you’re connecting with these plug adapters, your charger or device could wobble and maybe fall out. The connections inside are solid enough that this shouldn’t happen, but it’s possible. Our universal-adapter picks, as well as the other Ceptics set we discuss below, have a larger “face” for your charger to brace against—more like that of a traditional outlet—so there’s less chance of gravity having its way with your gear.

Being small and inexpensive, plug adapters are not built for high-power, high-wattage items, though hopefully we’ve persuaded you to leave those at home. If you’re charging a battery, you should be fine. If you’re running a motor, probably not. Laptops, yes; mini-fridges, no.

Last, these things being so small, you could easily lose them in your bag or leave them behind in an outlet somewhere, if you’re the type of person who loses things. (That’s why I usually keep mine connected to my charger.)

For a hardcore traveler like me, these are my pick. They’re cheap, light, and small, and they work.

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Every adapter you see in this guide merely sends the current from the wall directly to whatever you plug into it. These are not voltage converters. Which is to say, if you’re in the UK, whatever you plug into the front of the adapter is going to get the UK’s 220 volts/50 hertz electricity, not the 120 volt/60 hertz that you’d get in the US. Travel plug adapters don’t convert the voltage; they only convert the plug. (Our universal picks do convert the local current to USB voltage, but only for the USB ports.)

However, for the vast majority of people, this is all you need. It’s exceptionally rare that anyone would need a voltage converter anymore. This is because most so-called wall warts, like on your charger or your camera’s battery charger, will convert the wall voltage into what it needs automatically.

Take a look at your charger. Somewhere, it should say “100–220V 50/60Hz.” This means it can accept anything between 100 V and 220 V, which covers domestic electricity pretty much everywhere, and either 50 Hz or 60 Hz, which again covers everything. If your charger doesn’t say this, it might not work with a travel adapter. If it only says "120V–60Hz," it will almost certainly not work—or not work correctly—with a travel adapter.

But here’s the other reason we don’t recommend buying a voltage converter: Your device might not work even with one. Anything with a motor (like hair dryers), anything with a heating element (like a clothing iron or a curling iron), or anything with a plug that goes directly to the device (as in no wall wart), probably won’t work in another country regardless of what kind of converter or adapter you bring.

The good news is, pretty much every hotel, hostel, and Airbnb will have a hair dryer you can borrow. This is one of those times where we can’t cover everything you might want to bring, but for the vast majority of you, you don’t need a voltage converter. Either it’s not necessary, or the device that needs one won’t work anyway. Worst case, if it’s something cheap and you really need it—a hot pot or an electric kettle, say—consider buying one at your destination.

One occasional exception is electric razors. These often fall into the “single cable, no wall wart, has a motor” category. Which is to say, they probably won’t work without a voltage converter. (Again, check the fine print near the plug or on the device itself.) Many hotels have a shaver plug in the bathroom, with a US-style outlet and US-style 110 volt-or-so voltage. However, not every hotel will have these, and they’re very rare in hostels and Airbnbs. If you need one, best to call ahead and see if your hotel has them. Or use disposables on your trip.

It’s worth noting again for clarity, USB is USB, so if you’re just plugging in a USB cable, unless something is horribly wrong, one USB port’s voltage is the same as any other USB port’s voltage. How fast that port will charge your gear will vary (that’s related to amperage), but unless the charger is faulty, a USB port shouldn’t damage your gear.

The company is the world’s best Interchangeable Plug Power Adapter supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

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