If I'm playing with these little toys:
A 10W, 9-12V High Brightness LED Beads Chip: (https://www.aliexpress.com/item/32901524656.html?spm=a2g0s.90423184.108.40.206424c4dfKjvBR)
A fixed power supply that gives 12.4 V 3A: (https://www.aliexpress.com/item/32992892986.html?spm=a2g0s.90423220.127.116.11424c4dfKjvBR).
I don't know if I need to put a resistor in series to protect the LED, as it is needed with 5 mm standard LEDs.
Doing some maths, the needed resistor would be calculated using R = (Vs-Vi)/I, being I the desired Intensity current.
As the LED is rated at 10 W, its max intensity would be P = V x I; 10 W = 12 V x I; I = 10 W / 12 V = 0.83 A.
If I want to, let's say, protect the LED, I should apply a lower intensity, e.g. 0.75 A.
Then, going back to the formula to calculate the resistor, R = (12.4 V - 12 V) / 0.83 A = 0.48 ohms ?!
I'm pretty sure my calculations must be bloody and utterly incorrect, because such a ridiculous value for a resistor could not be right... or indeed it is telling me that I don't need that resistor...
- Do I actually need a resistor with this kind of LED?
- If so, how can I calculate its correct value?