JPS6019460B2 - Test equipment for indicating voltage, voltage polarity, and continuity of electrical conductors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention consists of two probes connected by a cable, including a light emitting diode connected in antiparallel and a ceramic positive temperature coefficient thermistor as a current limiting resistor connected in series with the light emitting diode. , relates to test equipment for indicating voltage, voltage polarity, and continuity of electrical conductors.

German Patent Application Publication No. 2060884 discloses that two light emitting diodes connected in antiparallel are used as a test device for indicating the conductivity or phase of a potential with respect to a predetermined reference potential. A device in which a current limiting resistor is connected in series is described. Both light-emitting diodes are arranged protected in at least one closure of a stylus-shaped case, which at the same time contains a current-limiting resistor and has a metal tip on one front side. The wall of the stylus-shaped case has a closure that allows the light emitted by the two light emitting diodes to be seen from the outside. The two light-emitting diodes are connected in antiparallel and are connected on the one hand to the metal tip via a current-limiting resistor and on the other hand to a test lead leading out of the stylus-shaped case. When testing DC voltage, one of the light emitting diodes emits light depending on its polarity, and when testing AC voltage,
Both light emitting diodes emit light. As a current limiting resistor, it is made of a strongly electrostatic material whose main component is n-type or p-type barium titanate, and has the property of dramatically increasing its electrical resistance by about 1 times in the Curie temperature range. If a ceramic positive temperature coefficient thermistor is used, voltages from about 2V to 500V can be tested with this device.

The ceramic positive temperature coefficient thermistor then serves to protect the light-emitting diode by limiting the current through self-heating above the Curie temperature and a consequent significant increase in resistance. However, in many cases, it is not only necessary to know whether a device is energized or energized and what its polarity is, but also to know whether electrical conductors, components, electrical assemblies, etc. It is important to be able to know whether or not it is flowing.

Therefore, this continuity test is particularly important. The continuity tester is
It works on the principle that a current is passed through the electrical conductor under test from a voltage source. Whether or not current is flowing is indicated by an acoustic or optical signal. US Patent No. 387095
Specification No. 3 includes an input protection circuit for such a conduction tester, including a power supply and a current indicator specific to testing a voltage-free current circuit, and a protection circuit that may damage the current indicator. It includes a semiconductor switch and a positive characteristic resistor in series to protect against harmful external voltages, and the free end is the input terminal, and the power supply and current indicator are connected in series, and the series circuit The free end is described as being connected on the one hand to the free end of a semiconductor switch and on the other hand to a connection point between the semiconductor switch and a positive resistance resistor. It is an object of the invention to configure a test device known per se for indicating voltage or its continuity so that it is also suitable as a test device for indicating the continuity of electrical conductors, and to further improve the safety of the device. The purpose of the probe is to provide useful protection and contain all electrical components within only one probe.

This object is achieved according to the invention by providing a test device as mentioned at the outset, in which one of the probes contains a battery with a protection diode in front of it and is equipped with a push-button switch, the protection diode and the battery being connected in series; Moreover, it is connected to a closeable contact of the pushbutton switch, which in the rest state is connected to a parallel conductor that bridges the battery and the protection diode, and the circuit consisting of the pushbutton switch, battery and protection diode is connected to the reverse of the light emitting diode. This is achieved by connecting in series with a parallel circuit.

Advantageously, the pushbutton switch is arranged in front of a non-slip ring, which is known per se.

Advantageously, a Zener diode is provided in the parallel circuit for the pushbutton switch, which is connected to the bridging parallel conductor. In order to require only one relatively large probe and to provide only a contact tip on the second probe, in one embodiment of the invention all components of the circuit are integrated into one Built into the probe, a pushbutton switch is placed on the opposite side of the non-slip ring from the light emitting diode, and a battery is housed in a case that can be pulled out from the probe, with its electrodes sandwiched between contact springs. The case engages the probe in the loaded state with its protrusion.

If all parts of the circuit are built into only one probe, a push-button switch can be placed on the side of the probe that is wrapped by hand against the anti-slip ring.

A light emitting diode is mounted on the opposite side of the anti-slip ring from the push button switch, and on a line parallel to or perpendicular to the line of the probe. The battery is contained within a removable case, which case is configured so that the outer contour of the probe does not change in the loaded state. Advantageously, a ceramic positive temperature coefficient thermistor serving as a current limiter and a protection diode for the battery are integrated into the probe so that they can be accessed from the outside with the battery case removed.

If the Jena diode is provided in the parallel circuit for the pushbutton switch, it is advantageous if the Jena diode is integrated into the probe so that it can be accessed from the outside with the battery case removed.

When the battery case is pulled out, the contact part that is in contact with the battery will be exposed, so there is a possibility that your finger or screwdriver will touch the contact spring when using the test device to indicate the voltage. If the pushbutton switch is operated simultaneously when the protective diode bridging the pushbutton switch is simultaneously faulty, it is possible that this contact spring may be exposed to a high voltage. To avoid this, the battery case is designed to prevent such contact from occurring and to protect against the risk of incorrect operation of the push-button switch during voltage tests and to bridge the push-button switch when the battery is accidentally inserted into the bag. It is desirable that the structure be such that simultaneous failure of the diodes can be avoided. For this purpose, it is preferable that the drawer range of the case is limited and the closure of the space within the probe remains closed.

Advantageously, the case is provided with a projection on its bottom that limits the withdrawal of the case.

Furthermore, the case includes a cylindrical space for accommodating the battery, one side of which is partitioned by a wall with a closure that allows only the positive electrode of the battery to pass through, and the other side of which is open corresponding to the diameter of the battery. Advantageously, the length of the space between the two sides corresponds to the length of the battery excluding the positive electrode, and the length of the opening in the probe is adapted to the length of the case.

The invention will be explained below by means of examples and the accompanying drawings.

According to FIG. 1, the test device consists of two probes 1 and 2, which are at the same time the case for the electrical components and conductors necessary for the test device.

Blowboo is a light emitting diode 11 and 12 that can be seen from the outside.
has. A ring 13 surrounding the probe protects fingers from slipping and touching the voltage source. A metal tip 14 at the end of the blowboo is used as a contact element between the test device and the conductor under test. The same applies to contact tip 1 of probe 2.
The same can be said about 5. A cable 16 interconnects both probes. Professional. The probe 2 also has a ring 17 surrounding the probe to protect fingers from slipping and touching the conductor under test.

A push button switch 5 is provided on the surface of the probe between the metal tip 15 and the ring 17. A battery 3 and a protection diode 4 are further provided inside the probe 2, and these are connected to circuit elements built into the probe according to the circuit diagram shown in FIG. A battery and a protection diode as well as a pushbutton switch 5 can also be provided in the blowboo.

In this case probe 2 is used only for operating the test device (see FIGS. 4 and 5). In FIG. 2, terminals 14 and 15 correspond to the metal tips of the test device.

The positive temperature coefficient thermistor 18 is connected in series with the anti-parallel circuit of the light emitting diodes 11 and 12. A pushbutton switch 5 is also connected in series to this anti-parallel circuit, which in its rest position is connected to a contact 9 on the parallel conductor 10 side. The pushbutton switch 5 is of elastic construction and is actuated in the case of a continuity test to form a connection with the contacts 8 and thereby bring the battery 3 with its positive pole 7 and negative pole 6 and the protective diode 4 into the circuit. Connected. This test device operates as follows.

In the case of a voltage test, the pushbutton switch 5 is in the normal position, so that the voltage applied to the ends 14 and 15 is applied to the positive temperature coefficient thermistor and to one of the two light emitting diodes, causing one of the light emitting diodes to emit light.

When the voltage is alternating current, both light emitting diodes emit light, and when the voltage is high, self-heating occurs in the positive temperature coefficient thermistor exceeding its Curie temperature, so its resistance increases dramatically. The light emitting diode is thereby protected from high voltages. In the case of a continuity test, the pushbutton switch 5 is switched, so that current is passed from the battery 3 to the conductor under test.

In the circuit as a continuity tester, there is a possibility that AC or DC voltage may also be applied to the metal tips 14 and 15 by mistake.

As a result, a charging current flows depending on the trough quality, and thus gas is generated in certain cell elements, which can lead to damage in sealed cells. In the test device according to the invention, the ceramic positive temperature coefficient thermistor resistor already present for the protection of the light-emitting diode is also used for the protection of the battery, thus having the combined effect of virtually eliminating the risk of damage. However, since it takes a certain amount of time for a positive temperature coefficient thermistor to become high in resistance due to self-heating, this effect almost eliminates the risk of damage. The protection diode 4 acts effectively.A primary battery or a secondary battery can be used as the battery.For example, a 12V cell can be used.Instead of the protection diode, as long as the same function is guaranteed, for example, a transistor can be used. Alternatively, other semiconductor circuit elements such as triaxes can be used.In the circuit according to FIG. 3, in addition to the circuit according to FIG.
A diode 19 is connected in parallel with the bridging parallel conducting wire 10.

The diode 19 actually has three protective functions.

Firstly, the pushbutton switch 5 is protected from high voltages. In this way, it is avoided that incorrect operation of the pushbutton switch 5 leads to damage to the battery 3 and/or the protection diode 4 during high voltage tests. Thirdly, since attention is directed to the case where the battery 3 is not inserted or the battery 3 is discharged, erroneous understanding during the continuity test is prevented. The voltage of the voltage diode 19 should be selected depending on the voltage of the battery 3.

If the battery voltage is less than 15V, for example 12V, a Zener diode with a Zener voltage of 15V is particularly suitable. According to FIG. 4, the test device again consists of two probes 1 and 2.

In this example, the probe 2 only has the function of holding the contact tip 15 and the anti-slip ring 17, and the probe 2 and the conductor 16
The probe 1, which is connected by a probe 1, includes all the elements of the circuit shown in FIGS. 2 and 3. The blowboo is provided with a contact point 14 at the end opposite the transition to the conductor 16. The light emitting diodes 11 and 12 are
contact tips 14 so that they can be clearly seen.
and the anti-slip ring 13. Furthermore, the probe 1 has a push button switch 5 on the side opposite the light emitting diodes 11 and 12 with respect to the anti-slip ring 13, ie on the hand-wrapping side of the probe 1.

A battery 3 is mounted inside the probe with its poles 6 and 7 sandwiched between contact pins 20 and 21.

The battery 3 is housed in a case 22, which has a space 23 that accommodates the battery. The protrusion 24 is used to engage the removable case 22 with the wall of the probe 1 in the loaded state.

In order to remove the battery 3 from the space 23 of the case 22, the wall of the case is partially removed at one end 25, so that on both sides of the battery end there are free surfaces on which a person can grasp the battery.

Removal of the case 22 creates an opening for accessing components such as the positive temperature coefficient thermistor 18, the protection diode 4 and the Jenner diode 19 from the outside.

According to FIG. 5, the test device again has two probes 1 and 2, and in that respect the explanation for FIG. 4 applies.

FIG. 6 shows a case 22 having a cylindrical space 23 for accommodating the battery 3. As shown in FIG.

The space 23 is closed on the left side 30 in the drawing so that only the positive electrode 7 of the battery passes through the opening 31. On the other side, the space 23 is open according to the cross section of the battery 3.
Since the length of the space 23 between the sides 30 and 32 exactly matches the length of the battery excluding the positive electrode 7, the battery can be placed in the space 2
If you put it in 3 by mistake, the positive electrode will stick out to the right. In this case, when the case 22 is pushed into the entrance 26 (FIG. 5) of the probe 1, the positive electrode 7 protrudes beyond the outer dimension of the case 22, so that the positive electrode 7 prevents complete insertion.
As shown in FIG. 7, the case 22 has been pulled out from the probe 1.

However, the case cannot be completely removed because the protrusion 27 (FIG. 6) is against the drawer. Instead of the protrusion 27, a bulge 28 extending over the entire length of the case 22 may be provided. When the case 22 is restricted and pulled out as shown in FIG. 7, the opening 26 remains closed, so that the contact portion 20 or
You cannot touch 1. The protrusions serve to engage the case 22 in the fully loaded state). It is particularly advantageous to integrate the case 22 into the probe when the probe 1 itself is assembled.

That is, the probe 1 consists of two halves 33 and 34, as shown in FIGS. 5 and 7, which are firmly glued together along a line 35. Prior to this gluing, the probe half 33 can be elastically deformed in the area of the opening 26 so that the battery case can be inserted. Both probe halves 3
By gluing 3 and 34 along line 35, this elasticity is lost again, so that case 22 can no longer be removed unless the probe halves are also pulled apart at the same time. It is of course also possible to cut the projections diagonally, as shown by line 36 in FIG. 7, so that the projections act to some extent as reverse brocades. In this case, the battery case may be pushed in with strong force after the probe 1 is assembled, so that it can no longer be removed. According to this embodiment of the invention, when the test device is used for voltage indication, it is possible to prevent incorrect actuation of the push-button switch 5 and, if necessary, to prevent the protection diode 1 from bridging this push-button switch 5.
9 can be prevented from occurring in two ways: on the one hand, due to the contact of the contacts 20 and 21, and on the other hand, due to incorrect insertion of the battery into the space 23.

This is because if the negative electrode 6 of the battery 3 is inserted incorrectly, the contact part 2
This is because the negative electrode 6 of the battery 3 is present in the space 23 so as to be in contact with the contact portion 20 as in the normal case. Of course, the weight is placed on the part 20 that is touched by the user when the pushbutton 5 is erroneously operated while the voltage is being specified.
and 21 contacts.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway external view of the test device, Fig. 2 is a circuit diagram of one embodiment, Fig. 3 is a circuit diagram of another embodiment, and Figs. 4 and 5 are each of another embodiment. Partial cutaway external view, No. 6
The figure is a partially cutaway external view of the battery case, and FIG. 7 is a sectional view taken along line NN in FIG. 5 with the battery case pulled out. 1, 2...Probe, 3...Battery, 4
...Protection diode, 5...Push button switch, 8...Contact, 10...Parallel conductor, 11,1
2...Light emitting diode, 18...Positive characteristic thermistor. Fig. lFi9.2 Fi9.3 Fig. 4 Fig. 5 Fi9.6 Fig. 7

Claims (1)

[Claims] 1 Consists of two probes connected by a cable and having contact tips, one of which has a light emitting diode connected in antiparallel and a ceramic positive current limiting resistor connected in series with the light emitting diode. A test device for indicating voltage, voltage polarity and continuity of an electrical conductor, including a characteristic thermistor, in which one of the probes contains a battery preceded by a protection diode and is provided with a push button switch, the protection diode and batteries are followed in series,
Moreover, it is connected to a closeable contact of the pushbutton switch, which in the rest state is connected to a parallel conductor that bridges the battery and the protection diode, and the circuit consisting of the pushbutton switch, battery and protection diode is connected to the reverse of the light emitting diode. A test device for indicating voltage, voltage polarity, and continuity of an electric conductor, characterized in that it is connected in series with a parallel circuit. 2. The test device according to claim 1, wherein the push button switch is disposed between the anti-slip ring and the metal tip. 3. The test device according to claim 1 or 2, characterized in that a Zener diode connected to a bridging parallel conducting wire is provided in the parallel circuit for the push button switch. 4 All parts of the circuit are built into the probe,
A push-button switch is arranged on the opposite side of the light-emitting diode with respect to the anti-slip ring, and the battery, with its poles sandwiched between the contact springs, can be withdrawn from the probe and is inserted into the probe in the loaded state by means of a projection. 4. The test device according to claim 1, wherein the test device is housed in a suitable space of a case that engages with the test device. 5. The test device according to claim 4, wherein the ceramic positive temperature coefficient thermistor and the protection diode are built into the probe so that they can be accessed from the outside with the case removed. 6. The test device according to claim 3, wherein the Zener diode is built into the probe so that it can be accessed from the outside with the case removed. 7. The test according to any one of claims 1 to 6, characterized in that the drawer range of the case is limited so that the opening of the space within the probe is maintained in a closed state. Device. 8. The test device according to claim 7, wherein the case is provided with a protrusion on the bottom thereof for restricting withdrawal of the case. 9. The case includes a cylindrical space for accommodating the battery,
One side of it is separated by a wall with an opening through which only the positive electrode of the battery passes, and the other side is open corresponding to the diameter of the battery, the length of the space between the two sides excluding the positive electrode. 9. Test device according to claim 7, characterized in that the length of the opening in the probe corresponds to the length of the battery and is adapted to the length of the case.