LED Lighting
LEDs are miniature very low power solid state light sources sometimes used for low light output applications. They are commonly available in sizes from 2mm upwards. They have niche applications, but are not in a position to take over from other forms of lighting for general lighting service.
LED vs Fluorescent
Against:
- Even the highest efficacy LEDs have not reached the efficacies of the highest efficacy fluorescent lights.
- The lowest cost lower efficacy LEDs have not reached the efficacies of low cost linear fl or CFL.
- LEDs' upfront cost is much higher for anything beyond extremely small light outputs.
- LED light quality is poor compared to fluorescent.
- LEDs are not available in powers comparable to fl lights
For:
- Some, but far from all, LEDs have much longer lives than fl tubes. Many have shorter lives
- LEDs are more mechanically robust
- LEDs in very low powers are much smaller than fls
- The lowest power LEDs (fractional watt) are available in sizes 2mm to 10mm.
Things may change, as LED performance is getting better year by year. But they have not got there yet, despite the hype.
Colour
Coloured LEDs are available producing monochromatic colours as well as white. These LEDs are considerably cheaper than whites and suffer less from deterioration.
Ultrabright coloured LEDs are commonly available in 2mm to 20mm sizes rated 40mW for in the region of 20p-30p per LED. These LEDs are typically rated in the region of 2v 20mA, and must be supplied by a current controlled source.
These miniature LEDs are suitable for low level intense colour mood lighting. Their tiny size, minimal power consumption and safe low voltage makes them fittable almost anywhere. Their very low output makes them mostly used for dim but strongly coloured glows and nightlighting.
They may be used with glass shelving to give the glass edges a coloured glow.
Bicolour LEDs contain 2 dice of different colours back to back. These may be switched between the 2 colours, or may be faded from one colour to another at will by driving with ac and controlling the current in each half cycle separately.
Ballasts
LEDs themselves can not simply be connected to a power supply, they need external current control. This is built in to LED lamps intended to directly replace other lamp types, so these can simply be plugged in and used. However miniature LEDs are just the LEDs, so need a little external electronics.
Some options