POWER SUPPLY APPARATUS WITH CIRCUIT LOAD SENSOR

APPAREIL D'ALIMENTATION AVEC CAPTEUR DE CHARGE DE CIRCUIT

English Abstract

A power supply apparatus 10 with circuit load sensor provides an extension
cord 20 having first and second ends extending from an enclosure 30. Within
the
enclosure, a power supply indicator circuit 40 lights an LED in response to
the plug
of the extension cord being inserted into a live outlet. Also within the
enclosure, a
power consumption indicator circuit 60 lights an LED in response to
consumption of
power by a load plugged into the socket of the extension cord. A nominal
voltage
drop across a TRIAC 70 carried in-line with the neutral conductor within the
enclosure triggers the power consumption indicator circuit when the load draws
current.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A power supply apparatus for indicating the presence of electrical
power in an electrical outlet and for indicating that a load plugged into the
power
supply apparatus is drawings power, the power supply apparatus comprising:
(A) an electrical cord body having hot and neutral wires, a first end having
a standard electrical plug and a second end having a standard
electrical socket;
(B) an enclosure having input hot and neutral terminals electrically
attached to the first end of the cord body having the standard electrical
plug, and having output hot and neutral terminals electrically attached
to the second end of the cord body having the standard electrical
socket, and having hot and neutral conductors carried between the
input and output terminals;
(C) power supply indicator circuit means carried between the hot and
neutral conductors within the enclosure for annunciating when the
standard electrical plug is inserted into the electrical outlet, the power
supply indicator circuit means comprising a first current-limiting resistor
and a first LED wired in series;
(D) power consumption indicator circuit means, carried between a point on
the hot conductor and a point on the neutral conductor within the
enclosure for annunciating when the load plugged into the standard
electrical socket is drawing power, the power consumption indicator
circuit means comprising:

(a) a second current-limiting resistor, a second LED and an SCR
wired in series between the hot and neutral conductors; and
(b) a gate lead, carried by the SCR connected to a third current-limiting
terminal resistor, and therethrough to the output neutral
terminal attached to the second end of the cord having the
standard electrical socket; and
(E) a TRIAC carried in-line with the neutral conductor between the output
neutral terminal and the point on the neutral conductor within the
enclosure to which the series-wired second current-limiting resistor,
second LED and SCR are attached, whereby a nominal voltage drop
across the TRIAC caused by current consumption in the load results in
a change in the electrical potential of the gate lead, thereby causing
the SCR to become conductive and causing the second LED to turn
on.

Description

CA 02265137 2000-02-O1
BACKGROUND
When an extension cord, power strip or similar electrical power supply device
is used there is frequently an issue as to whether the electrical power supply
device
is operatively connected to power. Similarly, when a load is either remote
from the
end of the power supply device at which the operator is located or where the
power-
consuming load is silent, such as a car's block heater or battery charger,
there is an
issue as to whether the power-consuming device is properly attached and
drawing
current.
What is needed is an inexpensive and reliable way for the operator to
determine if the power supply device is attached to an operative power supply
and if
the load is operative and drawing current.
SUMMARY
The present invention is directed to an apparatus that satisfies the above
needs. A novel power supply apparatus with circuit load sensor is disclosed
that
provides an operator with indicator LEDs confirming that the apparatus is
connected
to power and that the load is drawing power.
The power supply apparatus of the present invention provides some or all of
the following structures.
(A) An extension cord provides an electrical cord body having "hot" and
"neutral" conductors, a first end having a standard electrical plug and a
second end having a standard electrical socket.
(B) An enclosure having input "hot" and "neutral" terminals electrically
attached to the first end of the cord body having the standard electrical

CA 02265137 2000-02-O1
plug, and having output "hot" and "neutral" terminals electrically
attached to the second end of the cord body having the standard
electrical socket.
(C) A power supply indicator circuit, carried between the "hot" and "neutral"
conductors, is adapted so that an LED indicator of the circuit is lit when
the standard electrical plug is inserted in a live electrical outlet.
(D) A power consumption indicator circuit carried between the "hot" and
"neutral" conductor is adapted so that an LED indicator of the circuit is
lit when a load plugged into the standard electrical socket is drawing
power.
(E) A TRIAC carried in-line with the "neutral" conductor between the input
and output neutral terminals within the enclosure, whereby a nominal
voltage drop across the TRIAC allows operation of the power
consumption indicator circuit.
It is there a primary advantage of the present invention to provide a novel
power supply apparatus having a power supply indicator circuit having an LED
indicator which lights to indicate that the apparatus is plugged into an
operational
power supply.
Another advantage of the present invention is to provide a novel power supply
apparatus having a power consumption indicator circuit having an LED indicator
which indicates that a load plugged into the apparatus is drawing current.
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CA 02265137 2000-02-O1
A s still further advantage of the present invention is to provide a novel
power
supply apparatus which consumes minimal power and which results in a
negligible
drop in line voltage.
DRAWINGS
These and other features, aspects and advantages of the present invention
will become butter understood with regard to the following description,
appended
claims, and accompanying drawings where:
Fig. 1 is a view of a circuit diagram disclosing the operation of the power
supply apparatus with circuit load sensor.
Fig. 2 is a perspective view of a version of the power supply apparatus with
circuit load sensor having a generally extension cord appearance.
DESCRIPTION
Referring generally to Figs. 1 and 2, a power supply apparatus with circuit
load sensor 10 constructed in accordance with the principles of the invention
is
seen. The power supply apparatus includes an extension cord 20 having first
and
second ends extending from an enclosure 30. Within the enclosure a power
supply
indicator circuit 40 lights an LED in response to the plug of the extension
cord being
inserted into a live outlet. Also within the enclosure, a power consumption
indicator
circuit 60 lights an LED in response to consumption of a power by a load
plugged
into the socket of the extension cord. A nominal voltage drop across a TRIAC
70
carried in-line with the neutral conductor within the enclosure triggers the
power
consumption indicator circuit when the load draws current.
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CA 02265137 2000-02-O1
As seen in Fig. 2, an extension cord 20 provides an electrical cord 21
typically
having three conductors for "hot", "neutral" and "ground", and having first
and
second ends 22, 23 carrying a standard 3-prong' plug 24 and a standard 3-prong
socket 25, respectively.
As seen in Fig. 2, an enclosure 30 is carried between the first and second
ends 22, 23 of the extension cord 20. The enclosure provides hot, neutral and
ground conductors 31, 32, 33 as seen in Fig. 1. Input terminals 34, 35 and 36
are
associated with the hot, neutral and ground conductors, respectively. Output
terminals 37, 38, 39 are associated with the hot, neutral and ground
conductors,
respectively.
Referring in particular to Fig. 1, the structure of the circuitry carried
within the
enclosure may be understood. A power supply indicator circuit 40 is indicated
within
the dotted lines. A current-limiting resistor 41 and an LED 42 are carried in
series
between the hot and neutral conductors 31, 32. The resistor 41 is typically
47k
Ohm, rated at 2°~ tolerance and'/Z Watt, but alternate values may be
substituted,
within reason, to control the brightness of the LED 42. The LED is typically
red, but
may be another color if desired.
The operation of the power supply indicator circuit 40 is easily understood.
When the plug 24 of the extension cord 20 is plugged into an active AC current
outlet, current passes through the resistor 41 and LED 42, causing the LED to
light.
The lit LED is an indicator to the user that the plug is correctly installed
in a live
outlet.
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CA 02265137 2000-02-O1
Continuing to refer to Fig. 1, the structure of a power consumption indicator
circuit 60 carried within the enclosure may be understood. The power
consumption
indicator circuit 60 is indicated within the dotted lines. A current limiting
resistor 61,
an LED 62 and a silicon control controlled rectifier (SCR) 63 are carried in
series
between the hot conductor 31 and a portion on the neutral conductor 32 between
the input neutral terminal 35 and the point of attachment of the TRIAC 70 to
the
neutral conductor. The resistor is typically 47k Ohm, rated at 2% tolerance'/Z
Watt,
but alternate values may be substituted within reason, to control the
brightness of
the LED 62. The LED 62 is typically green, but may be another color if
desired. The
SCR 63 is typically an NTE 5404, but may be substituted with a similar
component.
In assembly, the anode 64 of the SCR 63 is oriented to the hot conductor 31,
while
the cathode 65 is oriented toward the neutral conductor 32.
Continuing to refer to Fig. 1 the gate lead 66 extending from the SCR 63 is
connected to a current-limiting resistor 67 which in turn is connected to the
output
neutral terminal 38. The current-limiting resistor 67 is typically 47k Ohm
rated at 2%
tolerance and'/2 Watt, but may be selected from other values which are
consistent
with the gate requirements of the SCR selected.
As seen in Fig. 1 a TRIAC 70 is carried in-line with the neutral conductor
between the output neutral terminal 38 and the point on the neutral conductor
within
the enclosure to which the series-wired resistor 61, LED 62 and SCR 63 are
attached. A preferred TRIAC is the NTE 5815, but other similar TRIACs from
other
manufacturers may be substituted, where their pertormance characteristics are
similar.
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CA 02265137 2000-02-O1
The operation. of the power consumption indicator circuit 60 may be
understood by reference to Fig. 1 and the following discussions. With the plug
24 in
a live AC outlet and the LED 42 lit, the user may then plug a load into the
socket 25.
Where the load is silent, as a car's cold weather engine block heater, there
would
ordinarily be an issue as to the heater's operation.
When the load is drawing current, a nominal voltage drop of approximately
0.9 volts results across the TRIAC 70. This voltage drop results in a change
in the
voltage potential on the gate 66 of the SCR 63. As a result, the SCR changes
to a
conductive state allowing current to pass through the LED 62 causing it to
light.
When the load is not drawing current, there is no voltage drop across the
TRIAC 70 and the voltage potential of the gate 66 is such that the SCR is in a
non-
conductive state and the LED 62 is not lit.
The invention resides not in any one of these features per se, but rather in
the
particular combination of all of them herein disclosed and claimed and it is
distinguished form the prior art in this particular combination of all of its
structures for
the functions specified.
Although the present invention has been described in considerable detail and
with reference to certain preferred versions, other versions are possible. For
example, while preferred component manufacturers and part numbers have been
supplied, similar parts could be substituted. Therefore, the spirit and scope
of the
appended claims should not be limited to the description of the preferred
version
disclosed.
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The invention has been described in language more or less specific as to
methodical features. The invention is not, however, limited to the specific
features
described, since the means herein disclosed comprise preferred forms of
putting the
invention into effect. The invention is, therefore, claimed in any of its
forms or
modifications within the proper scope of the appended claims appropriately
interpreted in accordance with the doctrine of equivalents.
7

Representative Drawing