Browse Prior Art Database

Detector Input Interface Circuit

IP.com Disclosure Number: IPCOM000112796D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 61K

Publishing Venue

IBM

Related People

Floyd, RE: AUTHOR [+3]

Abstract

Described is a hardware implementation of a detector input interface circuit to provide the ability to attach a wide variety of detector sensor circuits to a computer input. An example of a train wheel detector is used to illustrate the use of the detector circuit.

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This is the abbreviated version, containing approximately 58% of the total text.

Detector Input Interface Circuit

      Described is a hardware implementation of a detector input
interface circuit to provide the ability to attach a wide variety of
detector sensor circuits to a computer input.  An example of a train
wheel detector is used to illustrate the use of the detector circuit.

      Because of the existence of numerous detection sensors, such as
used in the railroad industry for train wheel detection, their
outputs provide a wide range of voltages and frequencies.  Typically,
voltages can range from 4 volts to 24 volts, and frequencies can have
any polarity from DC to 7 KHz.  Because of the installation
environment, optical isolation is a requirement.  In order to
accommodate the wide variety of detection sensors for use with
computer technology, the concept described herein provides detector
input interface circuitry to accommodate the wide variety of sensors
available.

      Fig. 1 shows the portion of the circuity that allows the user
to adapt to the operating voltages required.  The circuit enables the
user to jumper to the desired position, a, b, or c, so that the
proper voltage ranges required can provide the proper current, 4 to
10 MA, to the optical isolator.  Fig. 2 shows the typical voltages
for each jumper position.

      Since most industrial optical isolation circuits provide not
only isolation but integration, they are normally slow, 10 to 30 MS.
The optical isolators that are equipped with communication
cap...