Diode Gate B117

This document is a proprietary electrical schematic, copyrighted in 1964 by Digital Equipment Corporation (DEC), and is intended solely for test and maintenance purposes.

Key details from the schematic:

• Title: DIODE GATE BI17 (Drawing No. BI17-0-1, Rev. B).

• Circuit Description: It depicts two identical multi-input diode-transistor logic (DTL) gates.

  • Each gate has multiple inputs (D through K for the first, N through U for the second) that feed through diodes (D1-D6, D9-D14) to a common point.
  • This common point then connects via two additional diodes (D7, D8, and D15, D16) to the base of a transistor (Q1, Q2, type DEC 2894-1).
  • The circuit is powered by +10V(A) and -15V supplies, with an output taken from the transistor's emitter (L, V, M) to ground (GND). A 0.01 MFD capacitor (C1) is present between -15V and GND.

• Component Specifications:

  • Resistors (R1-R4) are generally 1/4W and 10% tolerance (unless otherwise indicated). Specific values are 12,000 ohms (R1, R3) and 68,000 ohms (R2, R4).
  • Diodes (D1-D16) are primarily D-664 or D-662 types.

• Conversion Chart: A "Transistor & Diode Conversion Chart" provides EIA equivalents for DEC parts:

  • Transistor DEC 2894-1 has no EIA equivalent listed.
  • Diode D662 is equivalent to 1N645.
  • Diode D664 is equivalent to 1N3606.

• Personnel & Date: The drawing was prepared by H. Porter (DRN) and checked by N. Perryman (CHK'D) with engineering by B. Scudney (ENG) around May 1964.