LED circuit
In electronics, the basic LED circuit is an electrical circuit used to power a light-emitting diode (LED). It consists of a voltage source powering two components connected in series: A current limiting resistor, and an LED. Optionally a switch may be introduced to open and close the circuit. The switch may be replaced with another component or circuit to form a continuity tester.
The LED used will have a voltage drop, specified at the intended operating current. Ohm’s law and Kirchhoff’s circuit laws are used to calculate the resistor that is used to attain the correct current. The resistor value is computed by subtracting the LED voltage drop from the supply voltage, and then dividing by the desired LED operating current. If the supply voltage is equal to the LED’s voltage drop, no resistor is needed.
This basic circuit is used in a wide range of applications, including many consumer appliances.