How does an optocoupler work?

An optocoupler is an electronic device that isolates two circuits using light.

An optocoupler, also known as an opto-isolator, consists of an LED (light-emitting diode) and a phototransistor or photodiode. The LED emits light when a voltage is applied to it, which is then detected by the phototransistor or photodiode. The amount of light detected is proportional to the voltage applied to the LED.

The optocoupler is used to isolate two circuits that are at different potentials, which could cause damage or interference if they were directly connected. The input circuit is connected to the LED, while the output circuit is connected to the phototransistor or photodiode. When a voltage is applied to the input circuit, the LED emits light, which is then detected by the phototransistor or photodiode. This causes a current to flow in the output circuit, which is proportional to the voltage applied to the input circuit.

Optocouplers are commonly used in electronic circuits to provide electrical isolation between high-voltage and low-voltage circuits, to prevent noise and interference, and to protect sensitive components from damage. They are also used in digital communication systems, such as fibre-optic networks, to transmit data over long distances without interference.

In summary, an optocoupler works by using light to isolate two circuits that are at different potentials. It consists of an LED and a phototransistor or photodiode, which detect the amount of light emitted by the LED and convert it into a proportional current in the output circuit.