COUNTING GATE B166

This document is a schematic diagram for a "Counting Gate B166" circuit, copyrighted by Digital Equipment Corporation in 1967. It is intended for test and maintenance purposes only and states that the circuits are proprietary. The schematic details various electronic components including nine transistors (Q1-Q9), numerous diodes (D1-D49), eighteen resistors (R1-R18), and two capacitors (C1, C2). Power connections are indicated as +10V, GND, and -15V. Input/output points are labeled (e.g., LO, MO, ON, SO). A "Transistor & Diode Conversion Chart" provides equivalent part numbers between DEC and EIA standards for transistors (2N4258) and diodes (D662/IN645, D664/IN3606). General specifications for components are also provided: transistors are 2N4258, resistors are 1/4W, 5%, and diodes are D664, unless otherwise noted.