# US 4,399,370 A · Noise reduction method and apparatus

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 4,399,370 A
- Document ID: US4399370A
- Status: Granted
- Kind: A
- Application number: 06/339,966
- Filed: 1982-01-18
- Granted: 1983-08-16
- Earliest claimed: 1982-01-18
- Assignees: Honeywell Inc.
- Inventors: Keith J. Bulleyment
- Web page: https://patentgrep.com/patent/US4399370A

## CPC

- H02B 1/24: Circuit arrangements for boards or switchyards
- H02B: BOARDS, SUBSTATIONS OR SWITCHING ARRANGEMENTS FOR THE SUPPLY OR DISTRIBUTION OF ELECTRIC POWER

## Abstract

Apparatus for reducing noise due to switching transients in a control system having a plurality of inverting amplifiers located at a common site to receive individual switching input signals, a like plurality of relays located remotely from the amplifiers for individual energization and deenergization thereby in accordance with the switching signals, and conductors connecting the relays severally to the amplifiers, the apparatus comprising series circuits associated severally with the amplifiers, each series circuit including a resistor and a capacitor, having first terminals interconnected at a junction point and second, independent terminals, the inputs of the amplifiers being connected severally to the junction points, the input signals being connected severally to the independent terminals of the resistors, and the outputs of the amplifiers being connected severally to the independent terminals of the capacitors.

## Claims

### Claim 1

Means for reducing noise due to switching transients in a control system having a plurality of inverting amplifiers located at a common site to receive individual switching input signals, a like plurality of relays located remotely from said amplifiers for individual energization and de-energization thereby in accordance with said switching signals, and conductors connecting said relays severally to said amplifiers,
said means comprising series circuits associated severally with said amplifiers, each said circuit including a resistor and a capacitor having first terminals interconnected at a junction point and second, independent terminals,
means connecting the inputs of said amplifiers severally to said junction points,
means connecting the input signals severally to said independent terminals of said resistors,
and means connecting the outputs of said amplifiers severally to said independent terminals of said capacitors.

### Claim 2 (depends on 1)

Apparatus according to claim 1 in which the values of said capacitor and said resistor are chosen to reduce the rate of change of current in said conductors by a factor of between 10 and 100.

### Claim 3

A control system having a plurality of inverting amplifiers located at a common site to receive individual switching input signals, a like plurality of relays located remotely from said amplifiers for individual energization and de-energization thereby in accordance with said switching signals, conductors connecting to said relays severally to said amplifiers, series circuits associated severally with said amplifiers, each said circuit including a resistor and a capacitor having first terminals interconnected at a junction point and second, independent terminals, means connecting the inputs of said amplifiers severally to said junction points, means connecting the input signals severally to said independent terminals of said resistors, and means connecting the outputs of said amplifiers severally to said independent terminals of said capacitors.

### Claim 4 (depends on 3)

A system according to claim 3 in which said conductors extend generally parallel and are closely spaced for a major portion of their length.

### Claim 5 (depends on 3)

A system according to claim 3 in which said conductors are wires of a ribbon cable.

### Claim 6 (depends on 3)

A system according to claim 3 in which said relays are connected to a common source remote from said amplifiers, and a common return connects said source to said amplifiers.

### Claim 7 (depends on 3)

A system according to claim 3 in which said amplifier comprise Darlington pairs and said junction points are connected to the input bases of said pairs.

### Claim 8 (depends on 3)

A system according to claim 3 in which said amplifiers comprise transistors and said junction points are connected to the bases of said transistors.