Electrical theory 1.3b - LEDs SMD type

Here I'll explain in simple terms what SMD (surface mount device type of component) is. SMD was developed for robotic placement on a printed circuit board. 

A SMD LED is a very small, flat profile LED which can be single colour or multicolour RGB type that can produce a palette of colour combinations. SMD components can be bought but it's impractical to use them for home projects - so we'll look at strip lighting.

Usually 3 SMD LEDs and SMD resistors are connected as a section operating on 12VDC. Then sections are connected together to make a strip - see photos. HINT: When buying a strip, carefully examine the number of terminals on the LED: model 5050 LED has 6 terminals so it has RGB capability; model 3528 has 2 terminals so it has single colour capability per LED, but there could be multiple colours distributed on the strip. So it doesn't look as good as 5050!

Polarity marks are shown on the strip. Connecting the strip wrongly can blow it up and no light is emitted.

 

The actual SMD can’t be repaired but the damaged section can be cut out– see repair section.

                        Single colour strip                                   Multicolour SMD strip

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