Why Order Your Power Supply from an American Company
This article discusses the benefits of ordering a 12V Power Supply Adapters you need from a company based here in the USA, versus importing direct from China.
As a USA based manufacturer, wholesaler, distributor, or retailer, you are faced with some tough challenges and choices daily. Importing power supplies to power your products does not need to be one of them. While it is true that at first glance, buying a 12V power supply a little cheaper straight from China looked at closely, the deal may not be so good. Here is why.
First of all, shipping from china is slow and unreliable, not to mention expensive. While many factories promise great price, and initially low shipping cost, it has been my experience that as soon as they have the business, they will start pumping the shipping cost higher and higher, even if they charge the same for the unit itself.
The second problem with buying straight from overseas is the failure rate. It has been our experience that manufacturers will cut corners and cost as much as possible. If you do not know the factory, and have a long term relationship with them, they will use the cheapest possible material, lowest gauge wiring, thinnest plastics. This translates into an extremely high and rising failure rate. If you buy your power supply here in the US, if it fails, you can return it. Buying from china, you are out of luck as return shipping is super expensive. Once you figure in the cost of replacing failures, including buying and shipping them, the cost is no longer so low.
Finally, it has been our experience is UL listing. If you need to have a UL listed power supply, both for the certification of your product, as well as for safety and quality, it has come to our attention that a vast portion of listing on Chinese wholesaler sites are issuing fake UL listing stamps. This means that the power supplies are of inferior quality, have a higher failure rate, as they do not comply with UL minimum quality standards. Worse yet, they are often stopped, seized by customs on entry, leaving you with the disposal fee, and possibly a fine. We have seen this over and over again.
So, to sum it up, because of cost of shipping, importing, quality control, high failure rate, and fake UL listings, it seems like buying your 12v Power Supplies from a US based company, shipping from within the US, offers you the best protection, best lead times, and in the end, the best price.
Not ALL Power Supplies are Created Equal.
This article discusses the quality differences between different types of 12 Volt Power Supply Adapters, and how to choose the best one for your application.
These days, the choice in Power Supply providers is huge. You can order from a supplier within the US, or from one across the planet. You can find power supplies on major chain store web sites and little specialty suppliers. They range in price from as little as a few dollars, to fifty or more dollars, but what is the difference between a cheap power supply, and a really expensive one? If you can get a 12 Volt 5 Amp Power Supply for as little as $10, and as much as $70, what is the real difference, and how do you choose? To begin with, it is important to know that not all power supplies are created equal. Real quality differences do exist. The cheapest power supplies on the market can be made with subpar components. They might have low gauge wire that can barely hold the necessary current. They can have resistors and components that can fail within a few hours of use. Even when they don’t fail, some of the cheapest power supplies can put out unsteady levels of power. Voltage might vary by as much as plus or minus 15%. This will inevitably damage your valuable electronics. The question is this, what is the cost of the power supply failing? Is it worth risking a $1000 screen, or all the data on your hard drive, to save $5 on a power supply? And if the power supply fails, what is the replacement cost, what is the down time waiting for replacement of the defective adapter? It is often worth it to spend a little more on a quality component, then risk the damage and replacement cost of a substandard one. Does this mean that a more expensive power supply is necessarily better? Not by all means. Sometime the same power supply is sold for $10 by one supplier and $50 by another. So how do you choose? One thing you can look at is UL listing. If the power supply is UL (or CE) listed, you can be sure that all its components meet a minimum standard of quality. It also means that it receives a higher level of testing. UL listed power supplies are almost always better. Another way you can tell if a power supply is a high quality one is the warranty. Does the supplier offer no warranty, or a short 90 day warranty? That means the supplier does not stand by their product, and has no confidence in it. If on the other hand the supplier offers a one year long or more warranty, it means they are confident enough to assume the cost of unit failure. It is not a total guaranty, but it is a good sign.
What Is a an AC/DC Power Supply, and What Does It Do?
This article tries to explain the function of an AC/DC power supply by showing the difference between AC and DC current, the two major forms of electrical power that exist today.
All the 12V Power Supplies you see on 12vAdapters.com, and most other websites serve one single function. They take AC Power (Usually 120V or 240V, or anywhere in between), and transform it to DC power, usually between 12V and 14v. In order to understand this concept, you have to understand the underlying difference between AC and DC electricity. AC and DC are the two existing forms of electricity. AC stands for Alternating Current, and DC stands for Direct Current. As the name implies, DC runs in a single direction and direct line from positive to negative poles. AC on the other hand alternates its motion in one direction, then in the other, usually on a cycle of 50HZ or 60Z. This means that it changes direction 50 or 60 times per minute. While the generator of a DC current has a fixed magnet, and fixed positive and negative poles, the generator of an AC current has a rotating magnet. The rotation of the magnet reverses the relative position of the negative and positive poles 50 or 60 times a second, thus alternating the flow of the electrons in the wire at that rate. Initially both of these systems were in competition for wide adoption. Thomas Edison was a big proponent of DC power, while Westinghouse was pushing the use of AC current. In the end, AC current won because it travels much better over long distances. While DC current can only travel about 1-2 KM over electrical wire until it starts losing voltage, AC current can travel hundreds of KMs at a time. Currently, all household current is AC, but most small devices run on DC, which is the more stable and non-oscillating of the two currents. So what an AC/DC power supply does is that it takes the AC current that travels well all the way to your house, and converts it to DC current, which most electronics and motors run on.
Choosing a Power Supply for A DC Motor
This article deals with the special considerations you must make when you are choosing a power supply for a a DC motor. These special considerations require an understading of continous vs peak draw, and how they effect any specific 12V Power Supply.
When choosing a power supply for a DC motor, you must know two things about a motor. These are the continous draw of the motor, measured in AMPS, or Watts, and the Peak Draw. The continous draw is the amount of power, or load, that the DC motor pulls from the power supply when it is already running. This is usually a smaller number than the peak draw. It is often measured in Watts, which is equal to the Amperage of the motor, multiplied by the voltage. So a 5 Amp DC motor running at 12V will consume 60 Watts of power. This is called the continuos draw, and must be less than the contimous load rating of the power supply. THe other major factor to consider when selecting a power supply for a DC motor is the peak draw. This is the amount of draw when the motor is just starting up, going from a stopped to running state. This peak power limit is usually significantly higher that the continous draw... So if a motor draws 3A on continous running, it might draw up to 5 Amps or more for a few moments as it starts running. Most switching power supplies have a protection circuit, which will turn them off if load peaks beyond it's safe capabilities. You must ensure that the peak rating of the motor does not surpass the peak shutoff protection of the powr supply. An example is, that if you want to power a DC motor with a 3A continous draw, you must assume the peak draw as about 50% more, so you should select a 5A power supply. This will be enough to get through the peak power usage, and will of course have no trouble running the continous load of 3A. Hope that makes it clear.....
Understanding Amperage, and Selecting a Power Supply.
This article addresses a commonly asked question, what does amperage mean, and how do I select the correct amperage power supply for my device.
Amperage is an accurate measure of the amount of current passing any point in an electrical system (wire), at any given moment. If voltage can be considered the size of the the electrical flow, the Amperage is the speed of the flow; how many electrons pass a certain point in the wire per given number of seconds. When choosing the Amperage of a 12 volt power supply, it is important to realize that the Amp rating of the power supply represents the highest (maximum) load that it can handle. This means that a 12 Volt power supply rated at 5 Amps, can handle any load up to 5A, or 5000 mA. It would be safe to use that device for any smaller device or load, such as a 1A router, or 2A DC motor. It is not recommended to put a higher load on a power adapter than it is maximum rating. This will shorten the life of the unit, lead to quick failure, and possibly be a hazard. In order to find the maximum wattage of a power supply, you multiply the volts by the amps. For example, a 12 Volt 5 Amp power supply would be 12 x 5 which is equal to 60 watts. This means that the power supply can handle any 12V device, rated up to 60 Watts.