HOW TO Power A LED Strip | Check, Calculate & Determine Power Requirements

I got a couple of leftover LED strips on a roll that came without a power source, so today, let's figure out how to power them!
► STEPS
1) Check how big are each LED segments. A segment can be identified looking for the signs where the LED can be cut. Between 2 cut signs, here a pair of scissors, is a segment.
2) Look carefully at all the components on 1 segment. In our case, we have 1 segment = 3 x SMD 3528 LED + 1 x 120 Ohm resistor. Note: the resistor is here to limit the current through the segment, avoiding the LED to burn out.
3) Determine the voltage needed to power the LED strip. Each 3528 SMD LED requires around 3 Volts to light up, so 9 Volts total for the 3 LEDs. If we plug it to a 18 volt source, Ohm's law implies that 9 divided by 120 equals 75 mA will travel through the circuit. This is too much for what this type of 3528 LEDs can handle without overheating and prematurely dying. At 12 Volts, the current becomes 25mA which is perfectly fine for what the LEDs are able to handle. 12 volts is therefore a good voltage to provide to this LED strip.
4) Determine the total amperage needed. We know that at 12 Volts, 25 mA will be needed for 1 segment. But the LED strips is made of several segments that will also individually all require 25 mA.
With 27 sections, an LED strip will need at least 27 x 25 equals 675mA. Adding 20% overhead for safety, 810mA is a good choice.
With 16 sections, another LED strip (using the same components per segments) will need at least 16 x 25 equals 400mA, that is a minimum of 480mA including 20% overhead.
5) Determine the appropriate power adapter: Typically, you will not have a power source that matches the exact requirements you have calculated. But as long as you provide the right voltage, and more than the minimal calculated amperage, you will be fine. In my case, an old power adapter from a scanner delivering 12V and 1.25A is perfectly fine!
6) Enjoy the result (after soldering the power adapter wires be careful, polarity matters!!) onto the round copper pads) And the final result? In my case, a safer staircase.
► DISCLAIMER
Always make sure you operate in a safe and secure manner.
Playing with electricity can kill real bad.
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[@markwilliams2830]

Very well explained for a simpleton like me!There are some projects I would like to take on and this kind of Video keeps things simple and less daunting once the principle is grasped.Now I must try and understand about wiring these things in Parrallel before I attempt anything ambitious !Thank you for sharing this I have subscribed to this great channel.

[@TheLabOtomy]

Thanks for the feedback, and good luck with your projects!

[@AppallingScholar]

Thanks

[@TheLabOtomy]

Welcome

[@ShiftKoncepts]

quick question. If I have an LED that is 12v and uses 7 watts. Can I use a power adapter that is 12volts and has max output of 2 amps without a LED controller?

[@TheLabOtomy]

The LED will likely try to draw 7W of power and cause your 2 watts power supply to fail

[@atameraltan]

​@@TheLabOtomy disagree. The power supply is capable of supplying 24 watts as it outputs 2 amps at 12 volts, which is more than 3 times higher than the required power.

[@TheLabOtomy]

@@atameraltan You're absolutely right about the calculations, I see in my comment I read the PSU was 2 Watts... This said, there is also a need for the LED to limit current (to the correct specs). Without it, the LED will draw all it can, be overdriven and burn out

[@spicky2966]

POWER adapter resistors could replaced to march your requirements as well

[@TheLabOtomy]

Idd

[@Sir_William_Lawson]

Mine reads 122 and 152 on the resistor on one strip light..am already confused..kindly help out

[@TheLabOtomy]

Difficult to assess without seeing the circuit and how everything is connected but: 122 means a resistor of 1200 Ohm = 1.2k Ohm 152 means a resistor of 1500 Ohm = 1.5k Ohm If connected in series, this equates to a resistor of 2.7k Ohm If connected in parallel, this equates to a resistor of 670 Ohm (666.66)

[@Sir_William_Lawson]

@@TheLabOtomy thankyou🙏🙏

[@kylelambert1672]

3 led's. Ah, ah,ah

[@TheLabOtomy]

Ah