To get this started I think that a breakdown of each and every component would be a good idea. This way people know what they are, and why they need them.
HEATSINK – A heat sink is designed to increase the surface area in contact with the cooling fluid surrounding it, such as the air. Approach air velocity, choice of material, fin (or other protrusion) design and surface treatment are some of the factors which affect the thermal performance of a heat sink. Heat sinks are used to cool computer central processing units or graphics processors. Heat sink attachment methods and thermal interface materials also affect the eventual die temperature of the integrated circuit. In order to maintain a low junction temperature to keep good performance of an LED, every method of removing heat from LEDs should be considered. Conduction, convection, and radiation are the three means of heat transfer. Typically, LEDs are encapsulated in a transparent resin, which is a poor thermal conductor. Nearly all heat produced is conducted through the back side of the chip. Heat is generated from the PN junction by electrical energy that was not converted to useful light, and conducted to outside ambience through a long path, from junction to solder point, solder point to board, and board to the heat sink and then to the atmosphere. To further aid in the active transfer of heat a computer fan is used to increase the cool fluid (air) over the heat sink, dissipating the excess heat.
HIGH POWER LED’s - High-power LEDs (HPLED) can be driven at currents from hundreds of mA to more than an ampere, compared with the tens of mA for other LEDs. Some can emit over a thousand lumens.[83][84] Since overheating is destructive, the HPLEDs must be mounted on a heat sink to allow for heat dissipation. If the heat from a HPLED is not removed, the device will fail in seconds. One HPLED can often replace an incandescent bulb in a flashlight, or be set in an array to form a powerful LED lamp. Some well-known HPLEDs in this category are the Lumileds Rebel Led, Osram Opto Semiconductors Golden Dragon, and Cree X-lamp. As of September 2009, some HPLEDs manufactured by Cree Inc. now exceed 105 lm/W [85] (e.g. the XLamp XP-G LED chip emitting Cool White light) and are being sold in lamps intended to replace incandescent, halogen, and even fluorescent lights, as LEDs grow more cost competitive.
LED Drivers - An LED driver is a self-contained power supply that has outputs matched to the electrical characteristics of your LED or array of LEDs. There are currently no industry standards, so understanding the electrical characteristics of your LED or array is critical in selecting or designing a driver circuit. Drivers should be current-regulated (deliver a consistent current over a range of load voltages). Drivers may also offer dimming by means of pulse width modulation (PWM) circuits. Drivers may have more than one channel for separate control of different LEDs or arrays.
PWM – PWM can be used to control the amount of power delivered to a load without incurring the losses that would result from linear power delivery by resistive means. Potential drawbacks to this technique are the pulsations defined by the duty cycle, switching frequency and properties of the load.
0-10 V - is one of the earliest and simplest electronic lighting control signaling systems; simply put, the control signal is a DC voltage that varies between zero and ten volts. The controlled lighting should scale its output so that at 10 V, the controlled light should be at 100% of its potential output, and at 0 V it should at 0% output (i.e. “Off”). Dimming devices may be designed to respond in various patterns to the intermediate voltages, giving output curves that are linear for: voltage output, actual light output, power output, or perceived light output.
Lens's - A lens helps focus the light emitted from the diode to what ever degree is desired. Typically the higher the light is off the surface of the water the narrower the lens needs to be.
There is obviously a little bit of an art when assembling these and making sure that they are safe. Some of mistakes I made when I first started was making sure that none of the wires touched the actual star part of the LED. I blew several fuses from this. The star is electrically isolated from the LED but defininately electrically connected to the heat sink. So verifying all connections are not shorted to the board or heatsink is a huge one. Another is making sure that if you are screwing your LED's into your heatsink and good amount of thermal paste should be applied to make sure that there is no air pockets that will eventually cause a heat issue. If your led is not completely thermally connected to the heatsink you will not get the proper thermal management which could lead to something as small as spectral shift, to a chatostrophic failure of the lighting circuit. So keep that in mind when screwing these down, the heatsink is not completely flat (at the microscopic level) and has grooves that can cause issues down the road. A little thermal paste will help fill these voids and improve the management of heat alot better. THe next way of applying the PCB to the heatsink is through thermal adhesive. This is a permanent bond and will not allow a changing of the chip if there is an issue later. Though it is really efficient for installation purposes, and is good for thermal management.
The LED's themselves is where the majority of the confusion comes from. What LED do I use? How do I know that it is the right color? What is a BIN? Well lets start this off by stating that their are a lot of different companies out there offering a lot of different LED's. This becomes a huge debate, I believe that with the standards of LED's and the forever changing industry that will constantly have a bigger and better thing next week. We may never be at the top of this. So My recommendation is to do the research. Cree is obviously the most pushed LED in this industry, however there are several other manufacturer that meet and exceed our needs. So do research and find out what fits you best. I am currently running
