BUY PC121 https://www.utsource.net/itm/p/11648039.html

Description: PC121 is a 4-pin DIP (dual in-line package) optocoupler manufactured by Sharp. Features: High isolation voltage of 5000 Vrms High CTR (current transfer ratio) of 400% High speed response of 1.2 μs High temperature stability of -55°C to 125°C Low power consumption of 0.5 mW Application: PC121 is commonly used in applications such as motor control, switching power supplies, and signal transmission. It is also used in industrial automation, telecommunications, and automotive systems. (For reference only)