Esposito Wang

Posted on Feb 5, 2014

This projects builds upon the 2012 LED Flicker project. The goal is to build an ultra bright, multi-channel test light using extremely high power LEDs driven to their maximum rated current, and controlled precisely. By driving an array of 7 ultra bright LEDs, we aim to produce a world class LED flash. Instead of controlling the LEDs via PWMs, whi

Esposito Wang
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ch has properties of flicking between OFF and ON states, the goal of this project is to design a system that provides a constant current through each LED. The design mimics a camera flash with the use of super capacitors charged by a wall wart power adapter or benchtop supply. Each LED will be pulsed with a max of 1 amp of current. There are 7 different LEDs on the LED array module and each LED is flashed so that no two LEDs are on at the same time. The time duration that the LED is on and the time interval between LED flashes are adjustable to allow for ease of use. Modifications can be made so that this design can be charged with Alkaline or Lithium-Ion batteries to make the entire system compact and portable. In order to achieve this goal, we built a system using one current driver circuit for each LED, an Arduino micro-controller to switch each channel, and a super-capacitor circuit to provide the necessary current. This system is charged by a high power, efficient charging circuit which keeps the capacitors charged and ready to drive the flash. To get a system that produces a stable light output, the LED must be driven by a constant current. An approach to get a constant current is using the circuit to the right. The way this circuit works is that the feedback resistor and BJT combination sense the amount of current flowing though the LED and feed this signal back to the MOSFET gate controlling its voltage and hence...

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