Patent Application
20060028194
1. Field of the Invention
The present invention is directed to an electronic voltage polarity indicator that can be utilized in a vehicle environment for testing whether an electrical surface is at a positive or negative polarity, and to evaluate connectivity of low impedance.
2. Discussion of the Background
Instances often arise in which a person may want to determine whether an electrical surface has a positive or negative polarity. One common such instance is when installing components into a vehicle, such as an automobile. For example, if a remote vehicle starter or other automotive after market accessories are being installed into an automobile, it becomes helpful to be able to identify “dead” or “live” circuits, and instantly identified test point as being either positive or negative in polarity
Other examples in which it may be desired to determine whether an electrical surface has a positive or a negative polarity is when testing door pin switches, lights, fuses, computer inputs/outputs, and distributors.
One object of the present invention is to provide a novel electronic voltage polarity indicator for use with vehicles that can indicate whether a contacted electrical surface has a positive or negative polarity, and to evaluate connectivity of low impedance circuits.
A further object of the present invention is to provide such a novel electronic voltage polarity indicator in a device that is simple and safe to use, and that provides a clear and efficient display.
A more complete appreciation of the present invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, and more particularly to
As shown in
One of the benefits of the present invention is that the device of the present invention is fault-tolerant with respect to the connection of the connectors 20, 22. That is, with the structure in the present invention one of the connectors 20, 22 is connected to the voltage source and the other of the connectors is connected to ground, but it is irrelevant which one of the connectors 20, 22 is connected to the voltage source and which is connected to ground.
The connectors 20, 22 can be color coded, for example to be black and red so that the red connector clip 20 can be connected to a voltage source, e.g. a +12 volt power source, and the black connector clip 22 can be connected to ground in a vehicle. However, in this case the color coding is merely for a visual effect or for providing a comfort level to a user, but is not needed because the connectors 20, 22 can be connected to the voltage source and ground in either order.
Further, the electronic voltage polarity indicator 10 includes a probe 12 formed of a conductive metal material, two indicators 14 and 16, and an incandescent bulb 18. The incandescent bulb 18 provides two functions. A first function is to provide an indication when the connector clips 20, 22 are properly connected to a ground and a voltage source to indicate that the electronic voltage polarity indicator 10 is operating. A second function is that the incandescent bulb 18 can operate as a small flashlight to provide an illumination for the electronic voltage polarity indicator 10, for example when it is used in a darkened area such as under a dash in an automobile. Element 18 could also take the form of other light sources, such as a white LED.
Indicators 14 and 16 in a preferred embodiment are LEDs of two different colors that can provide an indication as to whether the probe element 12 is contacting an electrical surface with a positive polarity or a negative polarity. For example, the indicator 14 can be a red LED that when lit up represents that the probe element 12 is contacting a positive polarity electrical surface, and the indicator 16 can be a green LED that lights up when the probe element 12 is contacting a negative or ground electrical surface.
As shown in
The circuitry in
When the power terminal 22 is properly connected to power in the vehicle electrical system and the ground terminal 20 is properly connected to ground in the vehicle electrical system, the incandescent bulb 18 will glow to indicate those proper connections. Current will also flow through resistors R1 and R2 forming a Thevinin-equivalent voltage source at the junction J between the resistors R1 and R2. The Thevinin voltage will be half of the automobile supply voltage, and the current may be limited by a Thevinin-equivalent impedance of 500 ohms based on the selected component values.
If the probe element 12 is attached to a circuit presenting a return to ground through a low impedance, and thereby indicating the probe element 10 contacting a point with a negative polarity, light emitting diode 16 will be forward biased, and current will flow through LED 16 and LED 16 will glow to provide a green indication. The strength of the glow will be inversely related to the impedance of the ground path, and with properly selected component values anything less than 100 ohms will result in almost full brightness in the LED 16. The red LED 14, in this circumstance, will be reverse biased and will thereby not glow and be dark.
In a contrary situation, if the probe element 12 is attached to a point that returns to, e.g., +12 volts, i.e. an element having a positive polarity, diode 14 will conduct and thereby light up providing a red indication, and the green diode 16 will be dark.
If the probe element 12 connects to a point that alternates between power and ground as a voltage source, the LEDs 16 and 14 will glow alternately. If the frequency of alternation is high enough the LEDs 16 and 14 may both appear to glow steadily at the same time.
Thereby, evaluating which LED 16 or 14, or both, is glowing, i.e., whether the green LED 16 or the red LED 14 is, glowing, or if both are glowing, provides an indication to a user of the voltage polarity indicator 10 whether the point the probe element 12 is contacting a positive polarity, a negative polarity, or an alternating power source.
As noted above one of the benefits in the present invention is that it is irrelevant which one of the connectors 20, 22 is connected to power or ground. That is, the circuit of
With such a circuit, and as noted above, an electronic voltage polarity indicator is provided that is simple to use, which is inexpensive to produce, which is safe to use, and which provides a simple to understand visual indication of a polarity of a contacted electrical surface.
The embodiment shown in
Further, in this embodiment of
It will be obvious to those skilled in the art that numerous additional modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described herein.
