Optocouplers

Also known as optical isolators, optocouplers are devices which contain light-emitting and light-sensitive components and are designed to transfer or convert electrical signals by using light waves in order to provide coupling. It can also prevent rapidly changing voltage from a surge from distorting transmission or damaging components and are ideally suited for electronic devices. Apart from the LED light source, it contains a closed optical channel and a photosensor. Optocouplers are often categorised according to the number of channels, the operating temperature, the output voltage, isolation voltage, packaging type and current transfer ratio. Also, they can be classed by what type of sensor they use: photoresistors, photodiodes or phototransistors. A photodiode opto-isolator drives the switch of a solid-state relay while phototransistor opto-isolators tend to be much slower. A bidirectional opto-isolator contains two LEDs instead of only one. Optocouplers have a number of varying applications. Those containing linear isolators tend to be used in the audio or music industry. For industry and commerce, their use includes factory automation, in photocopiers and as light measurement instruments and auto-exposure meters. For specific fields, such as computing and communications, high speed optocouplers would be used which can send digital signals to a computer.