G830

This document is a proprietary electrical schematic for a Digital Equipment Corporation (DEC) +5V Regulator, model G830, copyrighted in 1970. It is intended for test and maintenance purposes.

The schematic illustrates a power supply circuit designed to regulate an input voltage (likely +15V, indicated as "+15V INPUT") down to a stable +5V output. Key features and functional blocks include:

1. Main Regulator Circuit: Centered around an integrated circuit (IC) E1 (DEC 1469G), which incorporates a voltage reference (+3.5V), a noise filter, and current limit & compensation functions. Transistors like Q5 (DEC3715) likely act as pass elements in the regulation path.
2. Power On Detector: A circuit comprising transistors Q2, Q3, and Q4, responsible for monitoring or controlling the power-up sequence.
3. Crowbar Protection: A crucial safety circuit (involving Q1, Q6, D1, D6 (5.1V Zener), and associated resistors) designed to rapidly short the +5V output to ground in the event of an overvoltage condition, protecting the connected load.
4. Remote Sensing: Features "+ SENSE" (E2) and "SENSE GND" (R2) lines, allowing the regulator to monitor the voltage directly at the load, compensating for voltage drops in the power delivery cables and ensuring accurate voltage regulation.
5. Program Voltage Input (S2): Suggests the possibility of external control or adjustment of the output voltage.
6. Component List: The document includes a comprehensive parts list with DEC part numbers, descriptions (resistors, capacitors, diodes, transistors, ICs), and quantities.
7. Conversion Chart: A "Transistor & Diode Conversion Chart" is provided, listing DEC part numbers and their common equivalents.

Overall, the document details a robust, proprietary +5V power supply regulator with built-in power-on detection, current limiting, remote sensing, and critical crowbar overvoltage protection.