A complete circuit diagram for the IC is not available in standard public datasheets, as "IN518" is likely an incomplete, misread, or internal part number . There is no popular or mainstream IC with the exact marking "IN518" from major manufacturers (e.g., Texas Instruments, Analog Devices, Maxim, NXP).
However, based on common electronic components, here are the most likely possibilities: The prefix 1N indicates a JEDEC registered diode , not an integrated circuit. 1N518 is a silicon rectifier diode (obsolete, often replaced by 1N400x series). in518 ic circuit diagram
AC Input o----|>|----o DC Output (half-wave rectifier) 1N518 In a bridge rectifier: four 1N518 diodes arranged in a diamond. If the marking was AD518 , that is a precision operational amplifier (Analog Devices, obsolete). If ICL8018 , that is a CMOS analog switch . A complete circuit diagram for the IC is