5000Vrms isolation — the galvanic barrier
The Vishay CNY117-3 is a single-channel phototransistor optocoupler in a 6-DIP through-hole package. It provides 5000Vrms of galvanic isolation between a DC input LED and a transistor output with base access. The 100% to 200% current transfer ratio at 10mA forward current gives you a predictable gain window for translating logic levels across an isolation boundary.
70V output and 50mA drive — what it handles
The output transistor is rated for 70V collector-emitter voltage and 50mA continuous current. That 70V ceiling is the key number for driving relays, solenoids, or higher-voltage logic inputs on the isolated side. The 400mV Vce saturation at rated current means minimal voltage drop when the transistor is on, so you keep most of the supply headroom for the load.
Switching speed — 2µs edges
That puts the useful switching frequency around 50-100 kHz for most applications. For higher-speed isolation (like serial interfaces), you'd step up to a digital isolator or a faster optocoupler family. The base pin access lets you tailor the switching threshold with an external resistor if needed.