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I have 7 shelves that are 4 feet across that I want to light with LED strip lighting. After searching and looking for an answer, I can't find anything that is clear.

They are indoor shelves and need to be dimmable.

What kind of power supply should I use to power the LEDs? I am not sure what power supply I need to use when I have seven 48 inch strips running in parallel.

The LED strips I have are 20 inch individual strips and are cuttable every 2 inches, so I will make 48 inch strips out of these. Here is the LED strip specification from the website I bought them from:

enter image description here

Any help on this would be awesome. I don't want to buy the wrong power supply.

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2.4 W per 20" = 0.12 W per inch.

7 shelves × 48" = 336"

336" × 0.12 W/inch = 40 W.

From P = VI we can calculate the required current = 40 / 12 = 3.3 A.

You need a 12 V, 4 or 5 A PSU with a 0 to 12 V voltage adjust capability. Usually for LEDs the dimming will be done by pulse-width modulation (PWM) which switches them fully on and fully off at a high enough frequency that the eye doesn't notice any flicker.

enter image description here

Figure 1. PWM signal transitioning from high pulse width (75%) to low (25%) and back again. Note amplitude remains constant. Image source and more reading on Dimmable mains power supplies.

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  • \$\begingroup\$ Changing PS output voltage is not the way to dim led. PWM should be. It needs some special PS , which able to dim. \$\endgroup\$
    – user263983
    Nov 21 '20 at 16:09
  • \$\begingroup\$ thanks guys! just what i wanted to know. \$\endgroup\$
    – kris118
    Nov 21 '20 at 16:17
  • \$\begingroup\$ @user263983: Of course. I forgot to mention it. Corrected. \$\endgroup\$
    – Transistor
    Nov 21 '20 at 16:27

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