How to Build a Circuit for Multiple LEDs

by Isaiah David

As long as you know the values of your LEDs, putting together a circuit for multiple ones is fairly straight-forward. Simply calculate how much resistance you need for the circuit, wire the LEDs up to a resistor and attach them in parallel to the power supply. This article assumes you know a few simple things about electric circuits, such as how to solder and what a parallel circuit is.

Write down some information about the LEDs you are using. You will need to know the number of LEDs and the voltage and amperage of each LED. Although you can wire a circuit with LEDs with different values, it makes things more complicated and should be avoided.

Use a LED circuit calculator to determine the resistors you need. If you decide to use the LED resistance calculator linked below, select the "parallel LEDs" tab and enter the value for the voltage of your power supply, the amperage and voltage of your LEDs and the number of LEDs you are using. The calculator will output values for the resistance of the resistor you need and the current rating it requires.

Wire in the resistor. Use a single resistor with a high enough current rating for the total circuit or wire each LED with its own individual resistor. If you are only using one resistor, wire it to the positive terminal of the power supply. If you are using individual resistors for each LED, wire each to the cathode (the wire adjacent to the flattened edge of the LED). Although this approach requires more resistors, it is a common approach because you can use standard resistors instead of high-power ones.

Connect the cathode of of each LED to the common resistor or, if each has an individual resistor, hook up each resistor to the positive terminal of the power supply. The important thing is to attach the positive terminal through the resistor to each individual cathode.

Connect one terminal of an SPST switch to the anodes--the free ends--of the LEDs. Attach the negative terminal of the power supply to the other terminal of the switch. Your LED light circuit is complete.

Tip

• check Although you can wire LEDs in series, parallel is almost always a better choice, particularly for large numbers of LEDs.

Warnings

• close If you are using large numbers of LEDs, check the circuit voltage amperage given by the calculator and compare it to the max amperage of the power supply. Although it takes a lot of LEDs to overload most circuits, it can be done.
• close Always unplug your circuit before working on it.