I was planning on using black like this one, when I had black plastic IR LEDs. Generally I'm going to be dissipating 1A * 2V * 4 LEDs = 8W per string, with two strings this is as much power as a LED light bulb for your home, and those get really hot.
#Anzo smada license
The license plate will also be part of the heat radiator. So this time I will use a nice blank metal license plate frame that will act as the heat sink. The other thing I learned is that heat is a big problem, and at 1A it is going to get very hot. I need to keep the frequency of switching in the >10kHz range to make sure the diode is on longer than the frame time of the camera so I'm certain it appears on in the picture, especially when it is bright out. That would require an amplifier to regulate with feedback and lots of high current parts. It is a lot easier to control pulse width than it is to build a constant current source at 1A. I can dump 5A peak through these and switch it on and off with a duty cycle of 20% and keep the steady state average to 1A. Generally people drive these big high power LEDs with switching circuits. Also the high power LEDs have a slightly higher forward voltage, so I can't put as many in series. That won't work well at 1A, I'd need a 3 ohm resistor and I'd need resistors rated for 3W! These are small enough that I could mount an array of 4 or 8 of them without drawing any attention. Last time I put chains of 6 together, which was 1.5V * 6 = 9V, and the remaining 3V dropped across a 30ohm resistor. I did learn that it is most efficient to put multiple LEDs in series. I was dropping 3V at 100mA in the resistors, so with 300mW the 1/2W resistors still get pretty hot. With 100mA I had plenty of trouble last time keeping the power in each component in it's rated range using a resistor as a current limit. These diodes run at 1A instead of 100mA, and can handle surges up to 5A.
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