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“Is this enough of LED controller around? Yes, there are many LED control guides we can find on the Internet. One objective of my quest was to control a powered LED panel with a defined profile light intensity and real-time clock, and a light sensor to double check the output of LED panel. The input, output of light intensity are logged into SD card for a post-analysis.What are the parts? Below are the parts I have in my projects, details will be present along the way.Optional: I want to mimic a profile of solar intensity, which depends on the region, and the reason. The profile is hours vs. intensity of light. I grew algae so that the particle properties (uE, a photon) of light is the primary metric (can be 2200 uE/m2-s in the range of 400-700 nm in the summer’s noon). Other light units are W/m2, lux, candle/ft. The conversion is between those sources have to be taken into account of the light source (or the spectrum of the light source).Optional: The key difference of my setup with other solar simulation is that I use an array to define a solar value (between 0-100%), and another array to store time value. With a defined time interval (5min), the program reads the real-time values, check a time value stored in arrays. If a new values (time, intensity) are found, the Arduino then writes those inputs via PWM pins to the enabling pin the LED driver. See the chart for a less wordy explanation.Important if you have not played with LED before: To turn on the LED, a voltage larger than the forward voltage is applied. The LED (which is a special diode) turn from non-conductible (the internal resistor is very large) to conductible (the resistant is very small). The chip will allow whatever current on DC source to run through. If no heatsink is provided, the chip will be burnt out because of too much heat. You have less than 2sec to see this busting of LED chip. And limiting the current below the forward current is a MUST.Here is a good intro to LED light:”

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