Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Power Circuit for Personal Computers in Vehicular Application

IP.com Disclosure Number: IPCOM000099934D
Original Publication Date: 1990-Mar-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 3 page(s) / 115K

Publishing Venue

IBM

Related People

Powell, KE: AUTHOR [+2]

Abstract

This article describes a power circuit which allows operation of a 24-volt printer in a 12-volt environment of a motor vehicle without the use of DC-DC type converters, power inverters, motor generators, or like devices.

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

Power Circuit for Personal Computers in Vehicular Application

       This article describes a power circuit which allows
operation of a 24-volt printer in a 12-volt environment of a motor
vehicle without the use of DC-DC type converters, power inverters,
motor generators, or like devices.

      Fig. 1 is a schematic presentation of the power circuit
disclosed herein.  Basically, 12 volts are taken from the vehicle
battery which is a very high capacity power storage device backed up
and recharged by the vehicle's alternator system, and using a small
amount of this available power to maintain the charge of two low
capacity 12-volt storage batteries, typically, gel cell types.
Through the power circuit the two small cells appear to be in
parallel to the 12-volt source and appear to be in series with the
24-volt load. Additionally, the circuitry monitors and controls the
state of charge in the small cells without intervention by the user.

      The vehicular power source of 12 volts is shown in Fig. 1 at
E1.  The output voltage of E1 is applied to the small storage cells
E2 and E3 via the conduction of transistors Q1 through Q4.  When
transistors Q1 and Q2 are in conduction, the source E1 is placed in
parallel with storage cell E2 and power is furnished to E2, restoring
it to normal voltage level.  The control of this level will be
discussed later. When transistors Q3 and Q4 are placed in conduction,
the source E1 is applied to cell E3 to restore its charge to a normal
level.  Transistors Q1 and Q2 are driven to conduction by a signal 1
that is out of phase with the signal 2 that drives transistors Q3 and
Q4.  The circuitry also provides the ability to cut-off all of the
transistors Q1, Q2, Q3 and Q4 by bringing both signal lines 1 and 2
to a low level.  This state is utilized when both cells E2 and E3
have been charged to a normal voltage level.

      To achieve the three states described above, state one being
the conduction of transistors Q1 and Q2 via signal line 1 being in an
active state, state two being the conduction of transistors Q3 and Q4
via signal line 2 being active, and state three being a
non-conductive condition of all transistors Q1 through Q4 via signal
lines 1 and 2 being inactive.  The functions of a dual monostable
multivibrator (MM) IC1, shown within the broken lines, have been
utilized in a manner so as to form a two-phase clocking circuit that
i...