S181

This document is a schematic diagram for a "DC CARRY CHAIN S181" circuit, copyrighted by Digital Equipment Corporation in 1965. It is explicitly stated that the schematic is for test and maintenance purposes only, and the circuits are proprietary.

The schematic illustrates a circuit primarily comprising:

• Seven transistors (Q1-Q7, type DEC3639B / 2N3639).
• Various resistors (R1-R22, with values from 1.5KΩ to 100KΩ).
• Numerous diodes (D1-D53, types D664 / 1N3606 and D662 / 1N645).
• One capacitor (C1, 0.01MFD 50V).

The circuit operates with +10V, -15V, and Ground power rails, and features multiple labeled input/output points (V, S, R, N, P, T, U, L, J, E, K, F, H, M, D).

The document includes a comprehensive parts list detailing the reference designation, description, and Digital Equipment Corporation part number for each component. A transistor and diode conversion chart is also provided, listing equivalent EIA part numbers. The drawing is identified as S181-0-1, Revision A, with a printed circuit board revision C.