Electrical theory 1.10 - Light controllers

In this section we'll briefly discuss how light controllers for LED lights work - this is a technical subject so it will not be deep. We'll look at the variety and use of controllers in the design section.

Key points:

• A controller is a little box which makes the lights flash in a pattern selectable on a switch. It may also include the diode bridge rectifier with Vac input supply .

• Controllers use an electronic circuit to turn on individual strings to give the pattern. The example below shows 4 strings being switched according to the control of a pattern generator. You will see 4 switches connected to the 0V rail - these are electronic switches which complement the LED configuration which is common anode, ie all anode terminals of LEDs are connected together to +Vdc.

• TECHinfo : the actual type of electronic switch varies according to the type of DC supply: pulsating DC can use SCR (thyristor), MOSFET, Transistor; constant DC can use MOSFET, Transistor.  

• HINT: if controller is supplied with Vac don't connect it to a constant DC power supply - it will mal-function!

Sketch shows typical block diagram for a controller and RHS is a photo of one.

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