The 4N25 family is an industry standard single channel phototransistor coupler. This family includes the 4N25, 4N26, 4N27, 4N28. Each optocoupler consists of gallium arsenide infrared LED and a silicon NPN phototransistor. Optocoupler, Phototransistor Output, with Base Connection.
1Pc * 4N25 Photo Transistor Optocouplers