A common question I get for the driver boards is "How many LEDs can I hook up?" and the answer is "It depends"
Not helpful, I know. Here is how to figure out the answer:
Every LED has a minimum operating voltage, called Vf (if you have the datasheet), but a ROUGH (and usually accurate) rule of thumb is:
Color of LED
Red: Vf = 1.6-2.2v (lets call it 2 volts)
Orange/Amber/Yellow 2.0-2.4 (let's use 2.2)
Green 2.0-3.0 (Let's call it 2.5)
White 3.0-3.6 (Let's call it 3.3)
Blue 3.1-4.0 (Let's call it 3.5)
Now, the LEDs need to be hooked up in SERIES - AKA the anode (positive) of one LED gets hooked to the Cathode (negative) of the next - and the first anode gets hooked to the anode(+) terminal of the driver, and the last cathode gets hooked to the Cath(-) terminal of the board
The circuit itself needs about .7 volts (7/10 volt)
Now add up the Vfs of your LEDs.
Two white LEDs? Figure 6.5 volts
Two red LEDs? Figure 4 volts
Add in that .7 for the board.
Again, two white, 7.2volts
Two red? about 4.25 volts
Now, the board can take any voltage 3-30 volts - is the voltage you are supplying greater than that calculated voltage? You are good
Let's do it the other way - we'll use DCC as an example:
DCC voltage is about 14 volts, give or take, but we'll call it 12 for buffer, also so the math works for DC power supplies
Subtract the .7 volts, so you get 11.3 volts
So,
RED 11.3v/2v = 5 LEDs, you might get 6
Orange/Amber/Yellow11.3v/2.2v = 5 LEDs
Green11.3v/2.5v = 4 LEDs, might get 5
White 11.3v/3.3v = 3 LEDs, slight chance of 4 if they are low Vf
Blue? 11.3/3.5 = 3 LEDs
That is assuming DCC power. Run off a 16v accessory bus, you'll get more. Run off 30v (the maximum) you'll more than double that
And yes, you can mix and match colors - the circuit doesn't care, so you could say run 2 red and 2 white
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