Browse Prior Art Database

Automated Electronic Ground Connection

IP.com Disclosure Number: IPCOM000099859D
Original Publication Date: 1990-Feb-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 4 page(s) / 100K

Publishing Venue

IBM

Related People

Kraus, RA: AUTHOR [+2]

Abstract

This article describes a circuit arrangement for a current sensor system which provides an electronic ground connection automatically in an automotive vehicle.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Automated Electronic Ground Connection

       This article describes a circuit arrangement for a
current sensor system which provides an electronic ground connection
automatically in an automotive vehicle.

      Some technician terminals use an analog and digital data
acquisition system.  Because of the inherent sensitivity of the
analog data acquisition system to ground loops, only the analog data
acquisition system can connect to vehicle ground.  There is a need to
connect the digital data acquisition system to the vehicle without
the need to attach the analog data acquisition system.  A circuit is
disclosed herein to automatically sense the need for a digital ground
path and a means to complete the ground path. The circuit also has a
built-in high current sense capability to eliminate catastrophic
damage caused by inadvertent high current ground loops (high power
short circuits).

      Fig. 1 is a block diagram showing the electrical placement of a
current sense system in a technician terminal.  Fig. 2 is a block
diagram of the system.  The heart of the system is a current sense
circuit that is capable of detecting overcurrent, reverse current,
and sense current.  Fig. 3 is a circuit diagram of the current sense
circuit.

      As shown in Fig. 1, the current sense system is electrically
located between an assembly line data link (ALDL), which is the
digital data acquisition system, and an ALDL connector located on the
vehicle.  When the ALDL connector is initially attached to the
vehicle and data is present on the vehicle ALDL, a current is allowed
to flow through capacitor C2 in the current sense circuit (refer to
Fig. 3).  The AC (data) voltage is routed through diode D1 where it
is allowed to charge capacitor C1.  The voltage on capacitor C1 will
continue to rise until transistor Q1 begins to become foreword
biased.  As transistor Q1 becomes forward bias...