It is a very popular type of power supply but its label which is a mix of numbers and symbols may as well be in a foreign language to the average person. What does 12V 2A mean? Also is it good for your LED lights and your old hard drive? Using the wrong one may be an innocent error or a very costly issue for your favorite gadget.

Sure. This guide is to put an end to your confusion and instead instill in you confidence. We are going to go over all that you need to know about this small but powerful power adapter. By the time you finish reading you will be able to choose the right adapter each and every time, which in turn will keep your devices powered and very safe.

What do you make of those numbers on your adapter?

Let out that we will begin with the label. Those numbers you see are more than just that, they are the precise measures of the power which is put out. To that end they are the first thing you should understand in becoming a pro at this.

• The ‘V’ for Volts (12V): Power Force.

Picture your home as a house with pipes running through it. Voltage (V) is the water pressure in those pipes. It is what pushes the electricity along. For a device to function right, it has to have just the right amount of pressure. If a device is made for 12V, it will need an adapter which gives out exactly 12V. Too much pressure (for example using a 19V adapter) will blow out its delicate inner parts, and too little (as in a 9V adapter) won’t have enough to get things going at all. This is the most critical value to get right.

• The ‘A’ for Amps (2A): Flow of Power.

The adapter brings 2 plates of food but the device only has an appetite for 1.5. No issue! That extra half plate is there just in case.

• Putting It All Together with Watts

Volts x Amps  Watts.So, for our adapter: 12V x 2A  24W. This reports that the adapter puts out a total of 24 watts of power. If your device reports its power requirement in watts (for example 18W) you can go the other way to see if your adapter is right for the job (18W÷12V=1.5A) which in turn confirms that your 2A adapter has plenty of capacity.

What do you use for this adapter?

Now that you have the label you may be wondering about which types of devices use this particular power supply. The 12V 2A adapter is very adaptable and it is the primary option for a large variety of low to mid range electronic products which require a consistent and dependably stable source of power.

Here are some examples of what you can power with a 12V 2A adapter:

LED Strip Lights: This is a very popular use. LED strips require a steady low voltage DC current to brighten up and even out. A 24W adapter does well to power several meters of average LED tape which in turn is great for under cabinet lighting, for that which goes behind your TV, or for do it yourself projects.
Wi-Fi Routers and Modems: At the core of your home’s internet system is 12V power. Routers and modems run 24/7, this adapter we put in provides the stable energy they require to stay connected without breaking down or over heating.
Security Cameras (CCTV): In many cases our security cameras for home and small business use 12V DC power. We see that a 2A adapter is what it takes to get enough power for all camera functions which include video recording, night vision which may require more power, and Wi-Fi connectivity.
External Hard Drive Enclosures: Those desktop external hard drives which have to go in to the wall use a 12V adapter. 2A capacity is enough for spinning the mechanical drive inside and for the data transfer electronics.
Small LCD Monitors or TVs: While large televisions are very hungry for power many small screens such as portable monitors, small kitchen TVs, and checkout counter displays do well with 12 volt power.|
Audio/Video Equipment: Devices that include audio mixers, guitar pedals, TV boxes, and some types of AV signal converters tend to use a 12V power source.
DIY Electronics Projects: In the case of hobbyist projects which include Arduino boards, Raspberry Pi add-ons, or other custom circuits a 12V 2A power supply is a must have for the workbench which in turn provides the needed power for motors, lights and a variety of sensors.

Will this adapter fit my device? A 3 step guide.

At this point of no return you have an adapter in one hand and a device which requires power in the other. Before you plug in, go through this short list which will prevent issues. Typically the required specs for your device are included on the device itself, by the power port, or on the original adapter.

Step 1: Voltage which is of utmost importance in the set.
For 12V you must use a 12V adapter.
You will for the most part be putting in more electrical power than it is designed to handle which in turn will burn out the circuits. You may see a flash and smoke, and that is the end of your device.
You are not applying enough pressure. The device may not turn on at all. If it does it will perform poorly, flicker, or die out intermittently.

Step 2: Check out the Amperage (More is Good, Less is not).
Here’s where you have some flexibility. The amperage rating on the adapter is the max it can handle. The device which you are charging determines the actual draw.
The rule is: The adapter’s amperage should be at least that of the device’s requirement.

Example 1 (It Works): Your router is at 1.5A. Also your 12V 2A adapter is ideal. It puts out 2A which is more than the router which will only use what it needs of 1.5A.

Example 2 (It Doesn’t Work): Your monitor requires 3A. Your 12V 2A adapter is insufficient. The monitor will attempt to draw 3A from an adapter which is able to put out only 2A. This will cause the adapter to overwork, overheat and in the end fail which may also damage your monitor.

Step 3: Check out the Plug (Polarity and Size).
Getting right with the volts and amps is pointless if the plug doesn’t fit or has the wrong electrical orientation.
Connector Size: Barrel shaped plugs in a wide range of sizes. We see the 5.5mm outer diameter with 2.1mm or 2.5mm inner diameter as the most common. If it is too loose or too tight the connection will not be secure.
Polarity: This is very important. What which part of the plug is positive  and which is negative – does is determine the polarity. Pay attention to a small diagram present on both the adapter and the device. It is a circle which has a dot in the middle, from which go out the  and – lines.
Center Positive: In the primary layout which is most present the center dot is connected to plus and the outer circle is connected to minus.
Center Negative: Less often but some of that equipment like guitar pedals use it. The diagram is reversed.
Matching up the polarity is just as important as that of the voltage. Get it wrong and you may cause a short circuit which in turn will damage your device.

What to do if you use the wrong power supply?

We have touched on this issue before but I would like to bring it up again. Using a non compatible adapter is a serious issue, they may not work at all and in some cases may damage your electronics.

Using the Wrong Voltage:
Too High: This which outperforms all others in terms of breaking a device. Like putting a garden hose to a fire hydrant we are talking about inordinate force beyond what the internal components are designed to take. In which you for sure will burn out the circuit board.

Too Low: This is a less severe issue but still present. The device will see reduced power. It may not turn on at all, also it may function improperly at which time a Wi-Fi router may constantly reboot.

Using the Wrong Amperage:
Too Low: This is what we see in terms of stress put on the adapter. A device which attempts to draw 2A from a 1A adapter will make the adapter work beyond its designed parameters. This causes the adapter’s internal components to overheat which in turn will greatly reduce the adapter’s life span. Also in a worst case scenario it may melt the plastic casing or present a fire hazard.

Choosing a Good Replacement: Beyond the Numbers.

If you no longer have your original adapter it is also possible that it has failed  in either case you will require a replacement. Though many generic adapters will work at all — some are better than others. Below is what you should check out in order to obtain a quality product that is also effective and safe.

Look for Safety Marks: Reputable adapters go in for in depth testing to ensure that they don’t overheat, short out, or present a safety issue. Look for certification marks on the label. As advised by government safety agencies like the U.S. Consumer Product Safety Commission, you should always look for marks from a nationally recognized testing laboratory. The most common are:

UL (Underwriters Laboratories): A safety certified mark in North America.

• CE (Conformité Européenne): The product is in compliance with the European EEC regulations of safety, health, and environment.
• RoHS (Restriction of Hazardous Substances): States that the product is free of some hazardous materials. Cheap and un certified adapters may save you a few dollars at the time of purchase but it’s not worth the risk to your expensive electronics or home.

Consider the Cable’s Length and Quality: Think of what you will be using the device for. Do you need a long cord to reach the outlet, or a short one will do? Also check the feel of the cable, a thin and flimsy one is going to fare worse over time. A thick and sturdy cable will last you longer.

Read Reviews from Real People: When shopping online user reviews are what you turn to. Pay attention to comments about durability, whether the adapter runs hot, and if the plug fits in tightly. A product which has very high ratings from many users is usually a safe buy.

Conclusion: Power up we go!

That small black box which we used to take for granted, the 12V 2A adapter, is in fact a technology workhorse that in the background supports many of our day to day activities which range from our home network to the light from our LED bulbs.

Through comprehension of what the numbers represent and by following a few basic rules you can handle any power adapter issue with ease. Also keep in mind the simple mantra:

1. Voltage must be an exact match.
2. Amperage is the same or greater which is what we see.
3. The connection has to be exact.

When you dig into that messy drawer of cables you will not have to guess. You will make a safe decision, out of which will come the revival of your favorite devices.

Frequently Asked Questions (FAQ)