M531

This document is a schematic diagram for a Negative Bus Converter, copyrighted in 1970 by Digital Equipment Corporation (DEC). It is explicitly stated as proprietary and furnished for test and maintenance purposes only.

The circuit design includes:

• Multiple Input Lines: Labeled BI through VI, which feed into integrated circuit gates (DEC7404, likely inverters or buffers).
• Eight Conversion Stages: These stages are largely identical, each featuring a DEC3009B transistor (EIA 2N3009), associated resistors, and capacitors (e.g., .01uF).
• Diode Networks: Output signals from the transistor stages are conditioned by D664 diodes (EIA 1N3606) connected to various negative voltage rails.
• Power Supply Rails: The circuit operates with several voltage levels: +5V, Ground (GND), -1.5V, -3V, and -15V. Decoupling and filtering are handled by various capacitors, including 15uF electrolytic capacitors for the negative rails.

General Component Specifications (unless otherwise indicated):

• Resistors: 3K, 1/4W, 5% (with specific exceptions like R33 at 300 Ohm, 1W).
• Diodes: D664 (EIA 1N3606).
• Capacitors: 150 pF, 100V, 5% (with specific exceptions like .01uF, 100V, 20% and 15uF, 20V, 10% for power supply filtering).
• Transistors: DEC3009B (EIA 2N3009).
• ICs: DEC7404.