I'm looking to power 50 3W red leds as cheaply as I can.
I have a 100W LED COB that I powered with an old laptop power supply (19.5V@4.62A), connected to a 150W DC-DC step up. This is a constant current setup I believe, as I control the voltage from the DC-DC board. Also, I have a 1 Ohm, 10W resistor attached to the LED. This setup works well, and I only drive the LED at 60%, max.
Laptop PSU>150W DC-DC>Resistor>100W LED
Can I do something similar to power these 3W red LEDs? How would I modify it? The whole setup cost me $12 USD. I know fairly little about electronics, so I want to make sure I'm doing things correctly. Also, the "data sheet" on my LEDS says "Forward Voltage:2.2V~2.8V Forward Current: 700mA", and even without doing any math, this doesn't add up to 3W, it's more like 1.68W. After checking all the LED sellers, they all seem to do this. What gives? I've heard of Red LED voltage drop, but don't understand how it works.