Optocouplers are a type of isolator that use a low-power optical signal to transmit one signal from one circuit to another independent circuit. Optocouplers are comprised of an infrared LED light source and an integrated photo detector which usually consists of a photodiode and detector circuit. This optical link or coupling provides electrical isolation between the two circuits which makes the trouble shooting and reliability of circuits more straightforward. These devices are often used to provide electrical isolation between digital signals on the same board, but they are also commonly used in medical and industrial instruments, motor control systems, and signal conditioning circuits. Optocouplers have very high input-to-output isolation voltage and low capacitance, which makes them suitable for signal transmission in high speed applications. Additionally, they manage the call back current of the circuit they are connecting, allowing them to protect against overloads.