Here’s a really simple and inexpensive Power LED driver circuit. The circuit is a “constant current source”, which means that it keeps the LED brightness constant no matter what power supply you use or surrounding environmental conditions you subject the LED’s to. Or to put in another way: “this is better than using a resistor”.
It’s more consistent, more efficient, and more flexible. It’s ideal for High-power LED’s especially, and can be used for any number and configuration of normal or high-power LED’s with any type of power supply. As a simple project, i’ve built the driver circuit and connected it to a high-power LED and a power-brick, making a plug-in light.
Power LED’s are now around $3, so this is a very inexpensive project with many uses, and you can easily change it to use more LED’s, batteries, etc.
- R3 : current set resistor – see below
- Q1 : small NPN transistor (Fairchild 2N5088BU)
- Q2 : large N-channel FET (Fairchild FQP50N06L)
- LED : power LED (Luxeon 1-watt white star LXHL-MWEC)
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