The 3N248 is covered by this 43.6 KB PDF, indexed under schematics but named only by its JEDEC part number. Devices in the 3N series are registered four-lead semiconductors, and this file shares its size with 3N246 to 3N252, implying a family datasheet. Expect pinout, ratings and mechanical drawings useful when identifying a component, measuring it in circuit or sourcing an equivalent. View it in any PDF reader and verify the marking on the fitted part matches the 3N248 entry.
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 @cyberlanelectonik. Enginerys does not host this file.
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The standard format for schematics, block diagrams, power-sequence charts and service manuals.