CA1036671A - Voltage drop warning apparatus - Google Patents
Voltage drop warning apparatusInfo
- Publication number
- CA1036671A CA1036671A CA217,351A CA217351A CA1036671A CA 1036671 A CA1036671 A CA 1036671A CA 217351 A CA217351 A CA 217351A CA 1036671 A CA1036671 A CA 1036671A
- Authority
- CA
- Canada
- Prior art keywords
- voltage
- negative
- transistor
- switching element
- resistance device
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Abstract
VOLTAGE DROP WARNING APPARATUS
Abstract of the Disclosure A series connection of a transistor, a light-emitting diode and a load is connected across a D.C.
power source. One end of a negative-resistance device is connected to the base of the transistor and the other end is connected to the junction between the load and the diode. The circuit memorises any voltage drop that occurs by bistable switching of the negative-resistance device.
Illumination of the diode indicates a voltage lowering or interruption of the power supply.
Abstract of the Disclosure A series connection of a transistor, a light-emitting diode and a load is connected across a D.C.
power source. One end of a negative-resistance device is connected to the base of the transistor and the other end is connected to the junction between the load and the diode. The circuit memorises any voltage drop that occurs by bistable switching of the negative-resistance device.
Illumination of the diode indicates a voltage lowering or interruption of the power supply.
Description
1~)36671 This invention relates to a voltage drop warning apparatus for warning that a voltage drop has occurred or is occurring. More particularly, the invention concerns a voltage drop indicator that is capable of indicating by means of a light-emitting diode that a voltage drop has once occurred or is now occurring.
In electronic digital clocks or other electric clocks operating with an A.C. power supply synchronized with the supply frequency, if once the power supply is ' ~ w ~
A 10 in.terrupted or disturbed, the time indication w~th forever lag behind, even after restoration of the supply. Often the user is unaware of the lag.
In clocks.operating with a D.C. power source, e.g., a dry cell, when the source becomes weak and reduces its output voltage below a specified threshold level, the time indication becomes inaccurate. To monitor any such weaken- -ing of the power source, a known voltage indicating device such as a light-emitting diode, a miniature incandescent lamp or an ammeter can be used, but the power consumption of any such permanently indicating device is a disadvantage.
One device previously proposed comprises a push-button switch -~
that is closed to check the voltage, but this device has the drawback that an indication of lowered voltage is only obtained when the button is pressed.
The ob~ect of the present invention is to provide a voltage drop warning apparatus that automatically warns of a voltage drop or interruption while avoiding the above disadvantage~.
To this end the invention consists of a voltage-drop warning apparatus comprising a series connection includ-ing a load, indicator means and a semiconductor switching .~
1(~366r~1 element having a control electrode, said series connection being for connection across positive and negative sides of a power source, and a negative-resistance device comprising a complementary connection of an n-channel field-effect transistor and a p-channel field-effect transistor, an end of the negative-resistance device being connected to a ~unction point between said load and the switching element, and the other end of said device being connected to said control electrode.
. This invention is applicable for indicating the occurrence of a voltage interruption in an A.C. power source.
This invention is also applicable for indicating the occurrence of a voltage diminution in a D.C. power ,~
source.
This invention is also applicable for warning of -;~
the occurrence of a time lag in an analogue or digital ~ ::
clock or the occurrence of errors in data from a data processing apparatus.
The preferred forms of the invention have the advantage that their construction is very simple, dispensing : ,' with mechanical devices such as a relay or ammeter, and the circuits consume very small power even for continuous indication.
Embodiments of the invention are illustrated by way of example in the accompanying drawings, in which: -,Figure 1 is a circuit of a negative-resistance device used in apparatus according to an embodiment of the present invention;
Figure 2 is a diagram showing a voltage-current 1~)36671 characteristic of the device shown in Figure l;
Figure 3 is a circuit of a warning apparatus according to an embodiment of the present invention;
Figures 4 and 4a are voltage-current characteristic diagrams for Figure 3;
Figure 5 is a circuit diagram of another example -of the present invention; and Figure 6 is a circuit diagram of still another ~-example of the present invention.
A negative-resistance device is explained in Figure 1 which shows a prior art circuit, see for example IEEE Transactions on Circuit Theory, March 1963, pages 25-35, article entitled "Synthesis of Electronic Bistable Circuits" by ~Ø Hill et al, and Proceedings of The IEEE, April 1965, page 404, article entitled "Negative Resistance ~
Circuit using two Complementary Field Effect Transistors" ~ `
by S. Ostefjeld.
In Figure 1, the gate electrode Gl of an n-channel type FET 21 is connected to the drain electrode D2 of a p-channel type FET 22, and the gate electrode G2 of the p-channel type FET 22 is connected to the drain electrode Dl of the n-channel type FET 21. The source electrodes Sl and S2 of FETs 21 and 22 are connected to each other.
When a voltage V is applied across two outer termin-als 31 and 32, i.e., across the drain electrodes (with positive ;
potential on the electrode Dl), a known current-voltage characteristic as shown in Figure 2 is obtained between the voltage V and a source current I. For a time from the starting voltage 0, the current I increases showing positive resistance characteristic as the voltage increases.
But the current also gradually shows a saturation 10366~71 characteristic so that after a peak current polnt m, at the flrst threshold voltage Vtl, the current declines as the voltage increases, showing a so-called negative-resistance characteristic, i.e., between the first and second threshold voltages Vtl and Vt2. Finally, when the voltage exceeds the second threshold voltage Vt2~ the current I enters a cut-off state which continues until the voltage reaches a break-over voltage Vt3 where one of the FETs begins to break-down and a break-down current results. In the circuit of Figure 1, there are a first stable region of 0<V<Vtl, and a second stable "OFF" region of Vt2<V<Vt3, with an unstable state in the voltage range of Vtl<V<Vt2. ~ -~
Figure 3 shows a first example of a voltage drop warning apparatus wherein a terminal B is connected to a D.C. voltage supply, e.g., a rectifier circuit powered by a commercial A.C. source. This voltage Vcc applied to the terminal B is selected to be between Vt2 and Vt3. A load resistor 2, a light-emitting diode 3 and the collector-emitter electrodes of a transistor 4 are connected in series across the D.C. power source Vcc. One end of a negative-resistance device 1, such as that shown in Figure 1, can be connected through a change-over switch 5 to the positive terminal B. The other end of the device 1 is connected to the base of the transistor 4. A normally closed contact 5b of the switch 5 is connected to the ~unction point A between the load resistor 2 and the diode 3.
In operation, the switch 5 is initially changed over to the normally-open contact 5a. A voltage Vcc is 0 then directly applied to the negative-resistance device 1, 16~366r~1 bringing the operating point of this device to the condition V=Vcc, I=0, in order to set the current to zero.
The switch 5 is then changed back to the normally-closed contact Sb to await a voltage interruption to be indicated.
If no interruption of the voltage occurs, since the transistor 4 is held "0FF" by the zero current in the device 1, the full source voltage Vcc is still applied to ;
the device 1. Therefore the operation point in Figure 4 10 remains at the point V=Vcc, I=0. The current through the ;
transistor 4 is zero and the light-emitting diode 3 remains "OFF". -If an interruption of the voltage occurs, the voltage across the negative-resistance device 1 becomes zero, so that the voltage-current condition of Figure 4 is brought to the point V=0, I=0, and the transistor 4 is "OFF".
Then, when the voltage supply is restored, the D.C. voltage at the terminal B increases towards the 20 voltage Vcc. For a voltage exceeding V=VBE, at the -~
terminal B, the transistor 4 is turned "ON", a current flowing from the terminal B through the resistor 2, the switch 5 and the device l,to the base and emitter of the transistor 4 and eventually to the ground. As a result, the diode 3 is lit. As the source voltage increases, the current through the device 1 increases along the positive gradient part of the characteristic curve of the device 1, and the collector current which is hFE times -that of the base current of the transistor 4 increases accordlngly.
- , . . . . . . .
lQ366~1 The resistance R of the load resistor 2 is so selected that the oblique line "Q" connecting the point V=0, I=VRc with the point V=Vcc, I=0~and representing the load resistance R crosses the positive gradient part of the characteristic curve at the point P. By means of this selection of the resistance R, even when the voltage at point B reaches Vcc, the current flowing through the device 1 remains stable at the value represented by the point P, and the diode 3 is lit with this steady current.
This illumination of the diode indicates that the voltage at the terminal B has been interrupted, thus warning the user of possible inaccuracy of the data processed or the time indicated after such incident.
After the device 1 and the transistor have been turned "ON", the user must reset the circuit in order to watch for any further voltage drop. Such resetting is achieved by applying the source voltage Vcc across the device 1 by changing over the switch 5 to the contact 5a to bring the device 1 to the state V=Vcc, I=0 to switch the transistor 4 "OFF" through elimination of its base current with consequent extinguishing of the diode 3.
The apparatus of Figure 3 is also capable of indicating a weakening of a dry cell or battery. For such an indication, the condition of the circuit is so selected that the gradient of the load curve "Q" is almost equal to or slightly gentler than the gradient between voltages Vtl and Vt2 of the characteristic curve for the device 1 shown in Figure 4a, and the voltage Vcc of the normal state of the dry cell or battery slightly exceeds the voltage Vt2.
When the battery or dry cell is normal, the lQ366ql :
oblique load curve "Q" does not intersect the curve portion tr, and therefore the operating point is V=Vcc, I=O. Accordingly, no base current and hence no collector current flows in the transistor 4.
When the dry cell or battery becomes weak and the voltage Vcc at terminal B falls below Vt2 and the oblique load -~
line "Q" for a low Vcc as is indicated by the broken line in Figure 4a intersects the characteristic curve in the region between VBE<V<Vtl. The operation is stable under these 10 conditions and a collector current flows through the -transistor and the diode 3.
Figure 5 shows another example of the present -invention having resetting means in the form of a spring return push-button switch 6 connected between the positive-power supply terminal B and the negative-resistance device 1. The junction between the switch 6 and the device 1 is directly connected to the junction point A between the resistor 2 and the light-emitting diode 3. Other parts are identical with those of the example of Figure 3.
Resetting is achieved by depressing the switch 6 for a short time. By this means the voltage Vcc is applied to the device 1 and the circuit is reset in the same way as explained with reference to Figure 3. This circuit is easier to handle~since the resetting switch 6 is self-restoring, reducing the risk of forgetting to return the resetting switch to the normal operating position.
Figure 6 shows still another example of the present invention employing a pair of light-emitting diodes, for instance a red-emitting diode 3 and a green-emitting diode . ,.
7. The diode 3 is connected in a manner similar to Figure 5, except that the order of the transistor 4 and the diode 3 1~366ql i8 reversed. A second transistor 8 is connected by its emitter to the diode 7, by its collector via a resistor 10 to the terminal B, and by its base via a resistor 9 to the ~unction point A.
In Figure 6 the circuit is first reset by a re-setting switch 6, as in the previous examples. When the potential at point A is higher than Vt2 in Figure 4, the device 1 and hence the first transistor 4 are "OFF". A
current flows through the resistors 2 and 9 to the base of the second transistor 8, turning it "ON". Hence the li~ght-emitting diode 7 is on. This green light indicates that the power source Vcc is in order.
When an interruption takes place in the power æupply and the potential at the terminal B falls below Vt2, or further to zero, and is later restored to the voltage Vcc, the device 1 turns "ON" in the manner already described, hence turning the first transistor 4 "ON", with its collector current represented by the point P in Figure 4, and lighting the diode 3. This red light indicates that the power source Vcc has suffered an interruption or reduction. When the red light is lit, the potential at point A is lowered. Therefore the transistor 8 is turned "OFF", extinguishing the green light-emitting diode 7.
Thus illumination of the green light indicates normal power supply; illumination of the red light indicates a past interruption or diminution of the power supply; and extinguishing of both lights indicates a current interrup-tion of the power supply.
An example of Figure S is as follows:
.
1~)36671 Negative-resistance device 1 consists of complementary FETs, i.e., an n-channel, junction-type FET and a p-channel, junction-type FET connected in the manner shown in Figure 1, wherein Vtl ----- 3V
Vt2 --~-- 7V
Vt3 ----- 22V.
Light-emitting diode 3 is a red-light emitting diode made of a GaAsO 6Po 4 crystal- ~-Transistor 4 is an npn-silicon planar transistor having a D.C. current amplification factor hFE f approximately 100.
The D.C. power source Vcc supplies lOV D.C.
The apparatus works as explained with the load `
resistance selected in a range of 400 to 1000 ohms.
An example of Figure 6 is as follows:
Negative-resistance device 1 consists of ~--complementary FETs, i.e., an n-channel, junction-type -FET and a p-channel, junction-type FET connected in the manner shown in Figure 1, wherein Vtl ----- l.OV
Vt2 ----- 2.5V
Vt3 ----- 28V.
Light-emitting diode 3 is a red-light emitting diode made of a GaAsO.6P0.4 crystal-Light-emitting diode 7 is a green-light emitting diode made of a GaP crystal.
_ g _ Transistors 4 and 8 are npn-silicon planar transistors each having a D.C. current amplification factor hFE of approximately 200.
The D.C. power source Vcc supplies 5V D.C.
The apparatus works appropriately as explained with the resistance of the resistor 2 ----- 150 ohms;
the resistance of the resistor 9 ----- 33,000 ohms;
and the resistance of the resistor 10 ----- 150 ohms.
~ithin the present invention, the circuit arrange-mènt is not confined to the abovementioned examples, and any variation within the scope of the present invention can be made. For instance, in the example of Figure 3 the diode 3 can be connected above the point A, i.e., between the point B and the resistor 2.
Also, the light-emitting diodes can be replaced by other warning means, for instance, buzzers or incande-scent lamps.
Further, a Darlington-Connection circuit with two transistors can be used in place of the transistor 4 or 8, if a larger output is required.
The negative-resistance device 1 can employ insulated gate type tso-called MOS type) FETs instead of the ~unction type PETs shown in the examples.
The apparatus is simple in circuit arrangement.
In the examples of Figures 3 and 5, the circuit has an advantage of substantially zero power consumption under normal conditions.
In electronic digital clocks or other electric clocks operating with an A.C. power supply synchronized with the supply frequency, if once the power supply is ' ~ w ~
A 10 in.terrupted or disturbed, the time indication w~th forever lag behind, even after restoration of the supply. Often the user is unaware of the lag.
In clocks.operating with a D.C. power source, e.g., a dry cell, when the source becomes weak and reduces its output voltage below a specified threshold level, the time indication becomes inaccurate. To monitor any such weaken- -ing of the power source, a known voltage indicating device such as a light-emitting diode, a miniature incandescent lamp or an ammeter can be used, but the power consumption of any such permanently indicating device is a disadvantage.
One device previously proposed comprises a push-button switch -~
that is closed to check the voltage, but this device has the drawback that an indication of lowered voltage is only obtained when the button is pressed.
The ob~ect of the present invention is to provide a voltage drop warning apparatus that automatically warns of a voltage drop or interruption while avoiding the above disadvantage~.
To this end the invention consists of a voltage-drop warning apparatus comprising a series connection includ-ing a load, indicator means and a semiconductor switching .~
1(~366r~1 element having a control electrode, said series connection being for connection across positive and negative sides of a power source, and a negative-resistance device comprising a complementary connection of an n-channel field-effect transistor and a p-channel field-effect transistor, an end of the negative-resistance device being connected to a ~unction point between said load and the switching element, and the other end of said device being connected to said control electrode.
. This invention is applicable for indicating the occurrence of a voltage interruption in an A.C. power source.
This invention is also applicable for indicating the occurrence of a voltage diminution in a D.C. power ,~
source.
This invention is also applicable for warning of -;~
the occurrence of a time lag in an analogue or digital ~ ::
clock or the occurrence of errors in data from a data processing apparatus.
The preferred forms of the invention have the advantage that their construction is very simple, dispensing : ,' with mechanical devices such as a relay or ammeter, and the circuits consume very small power even for continuous indication.
Embodiments of the invention are illustrated by way of example in the accompanying drawings, in which: -,Figure 1 is a circuit of a negative-resistance device used in apparatus according to an embodiment of the present invention;
Figure 2 is a diagram showing a voltage-current 1~)36671 characteristic of the device shown in Figure l;
Figure 3 is a circuit of a warning apparatus according to an embodiment of the present invention;
Figures 4 and 4a are voltage-current characteristic diagrams for Figure 3;
Figure 5 is a circuit diagram of another example -of the present invention; and Figure 6 is a circuit diagram of still another ~-example of the present invention.
A negative-resistance device is explained in Figure 1 which shows a prior art circuit, see for example IEEE Transactions on Circuit Theory, March 1963, pages 25-35, article entitled "Synthesis of Electronic Bistable Circuits" by ~Ø Hill et al, and Proceedings of The IEEE, April 1965, page 404, article entitled "Negative Resistance ~
Circuit using two Complementary Field Effect Transistors" ~ `
by S. Ostefjeld.
In Figure 1, the gate electrode Gl of an n-channel type FET 21 is connected to the drain electrode D2 of a p-channel type FET 22, and the gate electrode G2 of the p-channel type FET 22 is connected to the drain electrode Dl of the n-channel type FET 21. The source electrodes Sl and S2 of FETs 21 and 22 are connected to each other.
When a voltage V is applied across two outer termin-als 31 and 32, i.e., across the drain electrodes (with positive ;
potential on the electrode Dl), a known current-voltage characteristic as shown in Figure 2 is obtained between the voltage V and a source current I. For a time from the starting voltage 0, the current I increases showing positive resistance characteristic as the voltage increases.
But the current also gradually shows a saturation 10366~71 characteristic so that after a peak current polnt m, at the flrst threshold voltage Vtl, the current declines as the voltage increases, showing a so-called negative-resistance characteristic, i.e., between the first and second threshold voltages Vtl and Vt2. Finally, when the voltage exceeds the second threshold voltage Vt2~ the current I enters a cut-off state which continues until the voltage reaches a break-over voltage Vt3 where one of the FETs begins to break-down and a break-down current results. In the circuit of Figure 1, there are a first stable region of 0<V<Vtl, and a second stable "OFF" region of Vt2<V<Vt3, with an unstable state in the voltage range of Vtl<V<Vt2. ~ -~
Figure 3 shows a first example of a voltage drop warning apparatus wherein a terminal B is connected to a D.C. voltage supply, e.g., a rectifier circuit powered by a commercial A.C. source. This voltage Vcc applied to the terminal B is selected to be between Vt2 and Vt3. A load resistor 2, a light-emitting diode 3 and the collector-emitter electrodes of a transistor 4 are connected in series across the D.C. power source Vcc. One end of a negative-resistance device 1, such as that shown in Figure 1, can be connected through a change-over switch 5 to the positive terminal B. The other end of the device 1 is connected to the base of the transistor 4. A normally closed contact 5b of the switch 5 is connected to the ~unction point A between the load resistor 2 and the diode 3.
In operation, the switch 5 is initially changed over to the normally-open contact 5a. A voltage Vcc is 0 then directly applied to the negative-resistance device 1, 16~366r~1 bringing the operating point of this device to the condition V=Vcc, I=0, in order to set the current to zero.
The switch 5 is then changed back to the normally-closed contact Sb to await a voltage interruption to be indicated.
If no interruption of the voltage occurs, since the transistor 4 is held "0FF" by the zero current in the device 1, the full source voltage Vcc is still applied to ;
the device 1. Therefore the operation point in Figure 4 10 remains at the point V=Vcc, I=0. The current through the ;
transistor 4 is zero and the light-emitting diode 3 remains "OFF". -If an interruption of the voltage occurs, the voltage across the negative-resistance device 1 becomes zero, so that the voltage-current condition of Figure 4 is brought to the point V=0, I=0, and the transistor 4 is "OFF".
Then, when the voltage supply is restored, the D.C. voltage at the terminal B increases towards the 20 voltage Vcc. For a voltage exceeding V=VBE, at the -~
terminal B, the transistor 4 is turned "ON", a current flowing from the terminal B through the resistor 2, the switch 5 and the device l,to the base and emitter of the transistor 4 and eventually to the ground. As a result, the diode 3 is lit. As the source voltage increases, the current through the device 1 increases along the positive gradient part of the characteristic curve of the device 1, and the collector current which is hFE times -that of the base current of the transistor 4 increases accordlngly.
- , . . . . . . .
lQ366~1 The resistance R of the load resistor 2 is so selected that the oblique line "Q" connecting the point V=0, I=VRc with the point V=Vcc, I=0~and representing the load resistance R crosses the positive gradient part of the characteristic curve at the point P. By means of this selection of the resistance R, even when the voltage at point B reaches Vcc, the current flowing through the device 1 remains stable at the value represented by the point P, and the diode 3 is lit with this steady current.
This illumination of the diode indicates that the voltage at the terminal B has been interrupted, thus warning the user of possible inaccuracy of the data processed or the time indicated after such incident.
After the device 1 and the transistor have been turned "ON", the user must reset the circuit in order to watch for any further voltage drop. Such resetting is achieved by applying the source voltage Vcc across the device 1 by changing over the switch 5 to the contact 5a to bring the device 1 to the state V=Vcc, I=0 to switch the transistor 4 "OFF" through elimination of its base current with consequent extinguishing of the diode 3.
The apparatus of Figure 3 is also capable of indicating a weakening of a dry cell or battery. For such an indication, the condition of the circuit is so selected that the gradient of the load curve "Q" is almost equal to or slightly gentler than the gradient between voltages Vtl and Vt2 of the characteristic curve for the device 1 shown in Figure 4a, and the voltage Vcc of the normal state of the dry cell or battery slightly exceeds the voltage Vt2.
When the battery or dry cell is normal, the lQ366ql :
oblique load curve "Q" does not intersect the curve portion tr, and therefore the operating point is V=Vcc, I=O. Accordingly, no base current and hence no collector current flows in the transistor 4.
When the dry cell or battery becomes weak and the voltage Vcc at terminal B falls below Vt2 and the oblique load -~
line "Q" for a low Vcc as is indicated by the broken line in Figure 4a intersects the characteristic curve in the region between VBE<V<Vtl. The operation is stable under these 10 conditions and a collector current flows through the -transistor and the diode 3.
Figure 5 shows another example of the present -invention having resetting means in the form of a spring return push-button switch 6 connected between the positive-power supply terminal B and the negative-resistance device 1. The junction between the switch 6 and the device 1 is directly connected to the junction point A between the resistor 2 and the light-emitting diode 3. Other parts are identical with those of the example of Figure 3.
Resetting is achieved by depressing the switch 6 for a short time. By this means the voltage Vcc is applied to the device 1 and the circuit is reset in the same way as explained with reference to Figure 3. This circuit is easier to handle~since the resetting switch 6 is self-restoring, reducing the risk of forgetting to return the resetting switch to the normal operating position.
Figure 6 shows still another example of the present invention employing a pair of light-emitting diodes, for instance a red-emitting diode 3 and a green-emitting diode . ,.
7. The diode 3 is connected in a manner similar to Figure 5, except that the order of the transistor 4 and the diode 3 1~366ql i8 reversed. A second transistor 8 is connected by its emitter to the diode 7, by its collector via a resistor 10 to the terminal B, and by its base via a resistor 9 to the ~unction point A.
In Figure 6 the circuit is first reset by a re-setting switch 6, as in the previous examples. When the potential at point A is higher than Vt2 in Figure 4, the device 1 and hence the first transistor 4 are "OFF". A
current flows through the resistors 2 and 9 to the base of the second transistor 8, turning it "ON". Hence the li~ght-emitting diode 7 is on. This green light indicates that the power source Vcc is in order.
When an interruption takes place in the power æupply and the potential at the terminal B falls below Vt2, or further to zero, and is later restored to the voltage Vcc, the device 1 turns "ON" in the manner already described, hence turning the first transistor 4 "ON", with its collector current represented by the point P in Figure 4, and lighting the diode 3. This red light indicates that the power source Vcc has suffered an interruption or reduction. When the red light is lit, the potential at point A is lowered. Therefore the transistor 8 is turned "OFF", extinguishing the green light-emitting diode 7.
Thus illumination of the green light indicates normal power supply; illumination of the red light indicates a past interruption or diminution of the power supply; and extinguishing of both lights indicates a current interrup-tion of the power supply.
An example of Figure S is as follows:
.
1~)36671 Negative-resistance device 1 consists of complementary FETs, i.e., an n-channel, junction-type FET and a p-channel, junction-type FET connected in the manner shown in Figure 1, wherein Vtl ----- 3V
Vt2 --~-- 7V
Vt3 ----- 22V.
Light-emitting diode 3 is a red-light emitting diode made of a GaAsO 6Po 4 crystal- ~-Transistor 4 is an npn-silicon planar transistor having a D.C. current amplification factor hFE f approximately 100.
The D.C. power source Vcc supplies lOV D.C.
The apparatus works as explained with the load `
resistance selected in a range of 400 to 1000 ohms.
An example of Figure 6 is as follows:
Negative-resistance device 1 consists of ~--complementary FETs, i.e., an n-channel, junction-type -FET and a p-channel, junction-type FET connected in the manner shown in Figure 1, wherein Vtl ----- l.OV
Vt2 ----- 2.5V
Vt3 ----- 28V.
Light-emitting diode 3 is a red-light emitting diode made of a GaAsO.6P0.4 crystal-Light-emitting diode 7 is a green-light emitting diode made of a GaP crystal.
_ g _ Transistors 4 and 8 are npn-silicon planar transistors each having a D.C. current amplification factor hFE of approximately 200.
The D.C. power source Vcc supplies 5V D.C.
The apparatus works appropriately as explained with the resistance of the resistor 2 ----- 150 ohms;
the resistance of the resistor 9 ----- 33,000 ohms;
and the resistance of the resistor 10 ----- 150 ohms.
~ithin the present invention, the circuit arrange-mènt is not confined to the abovementioned examples, and any variation within the scope of the present invention can be made. For instance, in the example of Figure 3 the diode 3 can be connected above the point A, i.e., between the point B and the resistor 2.
Also, the light-emitting diodes can be replaced by other warning means, for instance, buzzers or incande-scent lamps.
Further, a Darlington-Connection circuit with two transistors can be used in place of the transistor 4 or 8, if a larger output is required.
The negative-resistance device 1 can employ insulated gate type tso-called MOS type) FETs instead of the ~unction type PETs shown in the examples.
The apparatus is simple in circuit arrangement.
In the examples of Figures 3 and 5, the circuit has an advantage of substantially zero power consumption under normal conditions.
Claims (4)
1. A voltage-drop warning apparatus including a load, an indication means and a semi-conductor switching element having an input terminal for a control signal in a series connection of which the ends can be connected to positive and negative ends of a power source, and a negative-resistance device comprising a complementary connection of an n-channel field-effect transistor and a p-channel field-effect transistor, one end of the negative-resistance device being connected to a point in said series connection between said load and the switching element, and the other end being connected to the input terminal of the switching element.
2. Apparatus according to claim 1, including a resetting means which can apply such a voltage across said negative-resistance device, as to render the switching element non-conducting.
3. Apparatus according to claim 1, including a resetting means which can apply such a voltage across the negative resistance device as to render it non-conducting.
4. Apparatus according to claim 1 or 3, including a second semi-conductor switching element having an input terminal for a control signal, the latter input terminal being connected to a terminal other than the input terminal of said first switching element, and a second indication means connected in series with the second switching element.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA217,351A CA1036671A (en) | 1975-01-06 | 1975-01-06 | Voltage drop warning apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA217,351A CA1036671A (en) | 1975-01-06 | 1975-01-06 | Voltage drop warning apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1036671A true CA1036671A (en) | 1978-08-15 |
Family
ID=4101993
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA217,351A Expired CA1036671A (en) | 1975-01-06 | 1975-01-06 | Voltage drop warning apparatus |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1036671A (en) |
-
1975
- 1975-01-06 CA CA217,351A patent/CA1036671A/en not_active Expired
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