LED

Light Emitting Diodes (LEDs)

LEDs include diodes that can give of infrared light that frequency is lower than humans can see naturally.

LEDs give off light dependent on their "band gap" characteristic voltages

White LEDs include all the three primary colors.

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LED diagram showing pinouts

The forward voltage of an LED is between 1.8 and 3.3 volts dependent on the color(Frequency) of the LED,

Frequency of visible light LEDs range from 430 terahertz(THz), seen as red, to 750 THz (trillion hertz), seen as violet.

LEDs need to have a current limiting resistor placed in series to run.

Light Emitting Diodes (LEDs) are not like ‘filament’ based light bulbs that you find in older touch designs.

Unlike touch bulbs, LEDs are what is called polarized devices and have a -ve(anode) and +ve(cathode) attributes (manufacturers normally donate this by the lengths of the connect wires on the LED ). As the LED name implies they are ‘diodes’ that allow current to flow in one direction and not the other.

LEDs due to the way they work, only emit light when connected one way around to allow a ‘forward bias’ across the semiconducting junction. The forward voltage of an LED is between 1.8 and 3.3 volts dependent on the color of the LED.

If the LED is connected the ‘wrong way’ around they would not give off any light but would be in ‘Reverse bias’ mode, and almost no current would pass through them.

The forward voltage varies by the color(Output Frequency of the photons) of the LED ranges from between 1.8 and 3.3 volts semiconducting band gaps.

LEDs can be run at higher voltages for a very short period as long as the power dissipated in the LED remains below its thermal limits, this is often used when many LEDs are multiplexed together to form multi pixel based LED display, Each LED being pulsed brightly ON and then OFF for a while.

Enjoy the wonderful world of electronics, but never run an LED without a current limiting resistor or control circuit.

Two coloured 2 pin LEDs have two LEDs wired in parallel, one each way around,.

Two pin garden LEDs are very clever multi coloured devices with a microcontroller and a voltage doubler built in. (run of 1.5 Volt solar powered rechargeable battery)

Other multi coloured LEDs have more than two connecting wires.

RGB LEDs

These LEDs have Red, Green and Blue LEDs in one package

Standard RGB LED

shift-register programmable LED

PL9823 RGB LED with P9823 chipset inside

Colour chart

Efficiency

Between 2012-2014 LED efficiency jumped from just over 60 lumens per watt to nearly 100 lumens per watt, and they may hit 150 lumens per watt by 2020.