How to Power Large Numbers of LEDs

68 Hacking Electronics

How to Power Large Numbers of LEDs

If you use something like a 12V power supply, you can put a number of LEDs in series, with just one LED. In fact, if you know the forward voltages fairly accurately, and the power supply is well regulated, you can get away without any series resistor at all.

So, if you have fairly standard LEDs that have a forward voltage of 2V, then you could just put six of them in series. However, it will not be terribly easy to predict how much current the LEDs will take.

A safer approach is to arrange the LEDs in parallel strings, each string having its own current-limiting resistor (Figure 4-16).

Although the math for this isn’t too hard, there can be a fair bit of it, so you can save yourself a lot of time by using an online calculator like http://led.linear1.org/led.wiz (Figure 4-17).

Figure 4-16 Powering multiple LEDs

Figure 4-17 The LED wizard