LED, Strips and Controllers: Part-5

   In the previous part, we have told about a single color LED Strips.

   At the END of the topic we promise you to talk about the multi- color LED Tapes.

   The RGB LED Strips may be saturated with LED devices of RGB type.

   We begin our explanation of their work’s principal with the most popular member: RGB5050 SMT Device.

   We don’t hide that, the RGB5050 is our favorite LED Device. We have developed a lot of very special  devices with them. Even that, we are using them, also with vertical montage – right angle montage.

   Are You interested How? We could explain if you have an interest of that. 

   OK, We just mention the secret – three SMD pads (the same as these on a  bottom left an area of PIC .1 ) for connecting with controlling traces, two additional trough holes out of the last mentioned SMD pads on the imaginary cross line. After soldering the RGB device, you need to place a custom made ∏ – shaped wire to connect with other three LED electrodes and to make a common electrode. That is the idea in a few words.

   At the picture below,  you can see, how the RGB LED looks like. It has a plastic package with crystal clear filling. On the bottom of the shapes as the cut conical reflector, you can see the  bounded three P-N Junctions of  Silicon semiconductor with GaAs. The P-N Junctions emitting three basic colors: Red, Green, and Blue. With these colors and combining them, we could create many lovely variants of interior lightening for example: In Your Kitchen or Your Living room (see the related videos at the bottom of this tutorial) or even your abstract idea of creating passive Ambient-Light (Ambilight is a trademark by Philips) at the back side of your TV (except It is Philips Ambilight TVs).

   The Pictures also shows the different dimensions of LED part and the preferred PCB footprint  to create the reliable and ” Ultimate ” device – Your own device.



PIC .1   RGB-5050 SMT LED

   In common case when are used RGB-5050 SMT LEDs to solder above then tape, there is 10 cm long pieces LED modules. Three parts, each of them with three different color LEDs into one package and current limiting resistors, bring to user 30 LEDs per meter with three controlling tracks – one per color.

The next Schematic (SCH. 1) is specially created for You, Dear Future Inventors, Scientists, and Explorers. 

   On the (SCH. 1), you can see the used components:

  • R1, R2, R3 – Current limiting resistors.
  • D1,D2,D3 – RGB LED components. We are trying to make the schematic more cool and readable  using punctured line to different the each LED RGB 10-cm Module.
  • Switches SW-R, SW-G, SW-B are added for a better understanding of explained topic. They simple connect each same named controlling track to the negative electrode of the Power Supply Source.

   Do you see something strange in the values of current limiting resistors?

   Why not every current limiting resistors have an equal value? 

   Do You Have an answer for this question?     Yes!You know the theory.  No!We will try to explain.

We have the current limiting resistor, and its value is depending of this equation :

R LIMITING =  ( UPOWER – ( UfLED * 3 ) )   /  ILED (desired LED current) ;



ILED – Current trough each LED’s P-N Junction

UfLED GREEN  =  3.0V/25mA

UfLED BLUE  =  3.0V/25mA

UfLED RED  = 2.0V/25mA

The difference in UfLED Voltages means different R LIMITING Values


RGB Tape Schematic-watermark-Hardware-Pro

SCH. 1   RGB Tape “Explorer’s” Design View


List with some useful parameters of a real RGB Tape:

  • LEDS per meter : 30 RGB LEDs,
  • 10 cm LED module,
  • 10 LED modules per meter,
  • POWER:  12V DC,
  • Power Consumption per meter:  7.5W,
  • Lumens per meter: 540 lm.



VIDEO. 1   HOW-TO-CUT, Connect and Power 7.2W /m RGB LED STRIP


VIDEO. 2   LED-Strip Lights : High-Quality versus  Low-Quality 


VIDEO. 3   LED Strip Lights – a restaurant using example

Don’t Stop To Create and to Invent, dear Explorers!

LED, Strips and Controllers: Part-6

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