817 series

The 817 series is a common designation applied to a family of optoisolators (also known as optocouplers or photocouplers). These devices are electronic components that transfer electrical signals between two isolated circuits using light. An optoisolator consists of an LED (light-emitting diode) and a photosensitive device, typically a phototransistor. When current flows through the LED, it emits light, which activates the phototransistor, allowing current to flow in the output circuit.

The 817 series is characterized by its small size, common usage in general-purpose applications, and relatively low isolation voltage (typically around 5kV). They are widely used for electrical isolation, signal transmission, and noise reduction in various electronic circuits. Different manufacturers produce optoisolators falling under the "817 series" designation, with slight variations in specifications, such as current transfer ratio (CTR), isolation voltage, and package type (e.g., DIP-4, SMD). Specific datasheets from the respective manufacturers should be consulted to determine the exact characteristics of a particular 817 series optoisolator. Common manufacturers include Sharp, Everlight, and Vishay, among others. The popularity of the 817 series stems from their affordability and ease of integration into circuit designs.