Electrical – DMX Control – 50W COB LED

I'm guessing the application you intend is to use UV curing resins by mounting a powerful UV source behind a diffuser lens and LCD screen as a light blocker. The LCD is kept just above the surface of the resin as the tank is filled and the LCD rather than the UV LEDs provides the image resolution. If this is the case, the LEDs can all be the same brightness, which is an advantage because you can use different voltages, 54V for all 15 LEDs in series, 18V for 3 strings of 5 LEDs, 10.8v for 5 strings of 3.

It's a benchtop device so you can get away with things being a bit bulkier, which will make things easier for you.

Cooling the LEDs is important, so you may want to look around the usual DIY sources for some massive aluminum heatsink or a bunch of smaller ones depending on how far apart the LEDs are. The MCPCB stars that most power LEDs come mounted to are actually usually adequate for low power, especially with current control, but if you're going to have 15W together in an enclosed space beside an LCD you don't want to heat up, it wouldn't hurt at all to keep it cooler. This will also help avoid a long heat up time while you wait for the LEDs to reach thermal equilibrium and for their brightness to steady. LED efficiency also improves if you keep them cooler.

As for a driver, because it's a desktop unit you can get yourself a constant current LED driver of appropriate voltage range for the series/parallel arrangement you decide to use. They're usually about 4-5 inches by 2 inches by 1 inch or smaller depending on power rating. 120 or 240V goes in, constant current comes out to drive the LEDs. If you choose one that's dimmable you'll be able to adjust brightness if you want.

Here's a link to the section on DigiKey. You can find this sort of thing at numerous websites and sometimes even hardware stores, so you can use this to get an idea what you're looking for. Just fill out columns with things you do know, one at a time, and use "apply filters" in between until you narrow it down. Constant current is usually used with LEDs to eliminate thermal runaway without using series resistors.

Fairy lights like the one in the question you link to are not series leds. They are all in parallel. A 5V supply for multiple series leds would not work. I answer how to get the forward voltage and current in that other question.

Since your doing the math, simply adjust each string to reflect parallel leds. This is assuming you are replacing the resistor in the fairy light string, and let's assume 60 leds, at 3.2v at 10mA instead of 3.6v at 20mA, for longer life. You can adjust as you'd like, or if you measure the actual numbers.

R = ( V source - V forward ) / ( If * N leds )
R = (5 - 3.2 ) / (.01 * 60)
R = 1.8 / 0.6
R = 3 Ohms

This is per led string.

Don't forget to get the right power.

P = V * I
P = 1.8 * 0.6
P = 1.08 Watts

A 2 watt resistor would be good for these values.

The 10 Amps are the max you should draw from your supply, so you take your actual total current draw, and subtract that from 10 Amps. If it's less, you're good.