Datasheet for the SN74123N, a dual retriggerable monostable multivibrator with clear, in a plastic DIP package, provided as a 27.5 KB PDF. It gives the pinout, trigger function table and the formulas or charts relating the external resistor and capacitor to output pulse width. That makes it useful when a one-shot gives the wrong timing and you suspect a drifted timing capacitor. Confirm the logic family on the package, since timing equations vary between versions.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @datasheet_technar_org. Enginerys does not host this file.
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