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Make Sure you have control of the current to your LEDs

Most LEDs need a current-limiting device (whether that be a driver or resistors) in order to prevent LEDs from being over driven. This constant current driver or current limiting resistor is used to regulate current to the LEDs, keeping them running safe and maximizing their lifetime. Most finished LED products or LED strip lights (that you would buy straight from the store) already have drivers or resistors built in to regulate the current.

Constant Voltage Power Supplies

A constant voltage power supply can be used to power LED lights that have resistors or constant current drivers already within the system. These types of products will typically call for a constant DC voltage. If you are powering from a battery or happen to have a constant DC voltage that is adequate for your lights, then consider yourself lucky. Nine times out of ten this will not be the case and you will need a power supply to convert your power to a safe DC voltage for your lights. If you wanted to install this in your car, you wouldn’t need any power supply. Car's batteries give off 12VDC give or take. The 12V supply from the battery would be totally adequate for your lights. But in order to incorporate these strips in homes there is the need for an AC to DC converter that will take the 230VAC standard household voltage and convert it down to 12VDC.

How to Choose the Right Power Supply?

So, you need some type of constant voltage power supply that can convert your AC household voltage down to a safe DC voltage. There are many things that factor into finding the right power supply for your needs. First, we should lock down the power we require from our power source.

Wattage

To get started, find out how many watts your light will consume. If you hope to run more than one light off of one power supply, you must sum the wattages up to find the total watts used. Make sure to have a large enough power supply by giving yourself a 20% cushion over the total wattage you calculate from your LEDs. This can easily be done by multiplying your total wattage by 1.2 and then finding a power supply rated for that wattage.

Say for example we have 4 runs of LED strips that run at about 12 watts each. Simply multiplying these will show that our system wattage should be right around 48 Watts. Now we can add the 20% recommended cushion on with 48 x 1.2 = 57.6 Watts. A 60-Watt (or higher) power supply will suffice for this project.

Voltage/Current

When building an LED fixture or replacing a bad power supply, it is important to first verify that the output voltage is compatible with the LEDs voltage. LED products with built in current regulators will usually be pretty good about specifying what input voltage should be used. For instance, a 12V power supply would be used with our LED flex strips as that is what they require.