M650

This document is a schematic diagram for the "Negative Output Converter M650", designed and copyrighted in 1967 by Digital Equipment Corporation.

Key information includes:

• Purpose: Furnished for test and maintenance purposes, with the circuits being proprietary.

• Components: The design utilizes a mix of discrete components and integrated circuits.

  • Transistors: Primarily DEC3009B (equivalent to 2N3009) and DEC6534B (equivalent to MPS6534).
  • Diodes: Primarily D664 (equivalent to 1N3606) and D662 (equivalent to 1N645).
  • Integrated Circuits (ICs): Designated as DEC74ION, which are likely early TTL logic gates (indicated by standard TTL power pins: Pin 7 = GND, Pin 14 = +5V).
  • Passive Components: Resistors are generally 1/4W, 5%, and various capacitors are used.

• Power Supplies: The circuit operates with +5V, -15V, and Ground (GND), with an internal +1.2V reference point.

• Structure: The diagram shows multiple stages, each consisting of a logic gate (labeled E1) driving a pair of transistors and associated diodes, implying a multi-channel or multi-bit conversion function.
• Additional Information: A transistor and diode conversion chart is provided, along with revision history and drawing dates.