JPS5828668A - Testing device for voltage display and conduction test - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The invention consists of two grips connected by a cable, each having a contact tip and each containing one high resistance series resistor connected to the contact tip +7) fK. One of these grips has a voltage range (e.g. 6.12.24°50, 110.220.
880. 660 V), an oscillator capable of driving the optical display element of the display step assigned to the display step, an oscillator capable of driving an optionally provided acoustic signal generator, and an input current limited by both series resistors and a built-in battery. Display of the voltage and its polarity, including a step display of the voltage to be tested and possibly its polarity as well as a buffer amplifier that allows switching on of the acoustic signal generator by switching on and displaying the current from the battery. and regarding test equipment for continuity tests.

Such test equipment is ``WeidmullθrUIT''
It is commercially available under the name Weidmull.
Catalog of er company
it X 7”.This catalog is 1
It was first distributed to the public in Hannover-Messe in 980 (magazine "etz" volume 102 (198
1) No. 14, p. 747).

This known test equipment is the same as above (excluding 660v)
Displays the test voltage within the voltage range in steps. The series resistors contained within both grips and connected after the contact tips have a resistance of 5 MΩ each, or a total resistance of IOMΩ. A buffer amplifier separates the current flowing due to the voltage to be tested (test current) from the current flowing through the display element for step display of the voltage to be tested (display current). A test current generated by the voltage under test and limited by both series resistors is applied to the buffer amplifier. The display current flowing through the display element is supplied from a battery (12V) built into the test device, and is switched on by a transistor in a buffer amplifier.

A known test device includes a signal generator as described in German patent application no. This signal generator (buzzer) is 3
It includes a piezoelectric ceramic plate with two electrodes. An excitation voltage is applied to the two excitation electrodes, and a generated signal is acoustically extracted at the third electrode (return electrode) and applied to the input side of the amplifier via a resistor. An audio frequency signal generator with electro-acoustic feedback is thus constructed, the fundamental frequency of which is determined by the vibration parameters of the piezoceramic plate. A coil connected to this signal generator serves to increase the intensity of the sound.

In the known test device, an individual display step is divided into three groups. The display step for displaying the test voltage of 6V or more and less than 12V also serves to display the polarity of the DC voltage. In the case of AC voltage, both the light emitting diode for negative polarity display and the light emitting diode for positive polarity display emit light at the same time.

Display steps for voltage ranges of 12V or more, less than 24V; 24V or more, less than 50V and 50V or more, less than 110V constitute one cascade circuit;
Less than 220V; 220v or more, less than 380v and 38
The display step for voltage ranges above 0 V constitutes another cascade circuit.

Voltage dividers, transistors and light emitting diodes in these voltage indicating cascades are described in German patent application no. are connected like this. In this case, the individual voltage divider points of a voltage divider made up of several resistors are connected to the transistor pads associated with each display step, the emitters of these transistors being connected to a light display configured as a light emitting diode. The emitters of adjacent transistors are connected to each other through elements, and the collectors of these transistors are connected together to a common voltage source.

The known test device has one pushbutton switch, in its rest position the test device serves as a voltage test. In the activated position, this pushbutton switch is housed in a case according to DE 2756830 (see also FIGS. 7 and 8 of US Pat. No. 4,210,862). Since the battery is switched on, a continuity test of the conductor to be tested, if present, can be performed between the contact tips. Also, if both contact tips are brought into direct contact with each other, the battery (
The rated voltage is 12V), and the test equipment can be inspected for the health of the signal generator and polarity display element.

Self-checks regarding the soundness of other functions are not possible with known test equipment.

Test devices of the type mentioned at the outset, i.e. high-resistance test devices consisting of two grips, require, firstly, the safety of the user of the test device and, secondly, a unique marking and ease of handling. For this to happen, a number of requirements must be met, such as:

(1) The internal resistance of the test device is sufficiently high (50
0 to Ω or more).

For test equipment that has an internal resistance of 500Ω or more, if the AC voltage to ground is 220Ω, it is safe for the user to touch one contact tip while the other contact tip is energized. (contact safety).

(2) If the internal resistance is increased, the test current becomes minute, but the presence of voltage can be clearly and clearly displayed regardless of this. High internal resistance.

This ensures that almost no measurement error occurs even when the voltage source has high resistance, and also guarantees the contact safety mentioned in (1).

(3) Since the internal resistance of the test device is high, a voltage source other than the voltage to be tested must be prepared for the front element, that is, the test current itself cannot be used as the display current.

(4) A resistor with a high internal resistance and, in some cases, a high withstand voltage is used, so that even if a peak voltage occurs in the circuit under test, the user will not be exposed to danger due to dielectric breakdown.

(5) High-resistance series resistors are placed on both the grip containing the display element and the other grips to ensure user safety even if the cable connecting both grips breaks for some reason. What can be guaranteed.

(6) Display with sufficiently bright light and sufficiently loud sound.

(7) Be safe against possible erroneous operations.

As mentioned above in (1), an erroneous operation may occur when the user contacts one contact tip while voltage is being applied to the other contact tip. As mentioned above, even in such a case, the internal resistance of the testing device must be high to maintain the safety of the user. In addition, incorrect operation can cause high voltage (
For example, a pushbutton switch for a continuity test or self-inspection may be pressed while a power supply voltage (power distribution voltage) is being applied. Even in such cases, the applied voltage must be clearly displayed without posing any danger to the test equipment or the user.

(8) Test equipment with a built-in battery must be capable of self-checking the battery voltage.

(9) In addition to self-inspecting the battery voltage, it is also possible to inspect the health of the polarity display element and the voltage display element corresponding to the battery voltage by bringing both contact tips into direct contact with each other in continuity test mode.

00 The battery is switched on automatically, avoiding the possibility that the user forgets to switch it on and uses the test device.

0η It shall be possible to check the functionality of each display step before or during the voltage test.

(2) In addition to checking the display function (light step display and sound signal generation), it is also possible to check the health of the cable connecting both grips and the circuitry inside the test grip without the display function. Something.

a3 It is possible to display, for example, 660v as another voltage range above the voltage range of 380v.

(1 station) It must be possible to temporarily lower the high input internal resistance (over 600Ω).

British Patent No. 1562578, US Patent No. 421086
No. 2 and the specification of German Patent No. 2734883, etc., in a low-resistance test device for voltage and continuity tests, it is known that a full pushbutton switch is equipped with a It is known to connect diodes in parallel, and this measure guarantees safety against the above-mentioned requirement (7) in case the pushbutton switch is accidentally pressed while voltage is being applied.

Furthermore, among the above requirements, (1) to 4) and (8) to 0Q are met in patent application No. 30 of the Federal Republic of Germany.
This is also satisfied by the test device in the form of a screwdriver as described in US Pat. No. 04,784. However, this test device is monopolar, is not suitable for step display, and does not meet other requirements.

The above and other known test devices meet the requirements (1) above.
"I want to." Only Q was satisfied. That is, it is impossible to satisfy requirement 01 (adding a display step above the voltage range of 380 V), and it is not suitable to satisfy requirement α◇, (2), and (+41). .

The aim of the invention is to improve a test device of the type mentioned at the outset in such a way that it is able to meet all of the above requirements.

This purpose is achieved according to the invention in the test device mentioned at the outset, in which: a) a booster circuit is provided which is powered by the oscillator and serves to increase the oscillator voltage limited by the battery; An energy storage device, in particular in the form of a bow capacitor, is provided, which is connected to the output side of the booster circuit via the switching element and which is charged by the output voltage of the booster circuit while the switching element is in the rest position. c) The reed opening/closing element in the rest position during charging of the energy storage device transfers the charge present in the energy storage device to the input side of the buffer amplifier, thereby sequentially verifying the integrity of all display functions of the test device. 2) The oscillator can be switched to the operating position for checking, and 2) the oscillator is
The display current given to the display element of the test target voltage within the lower voltage measurement range (6V or more, less than 1.IOV) is switched on intermittently for a short time. It is connected to the base of the transistor (to chop).

e) In the rest position, another switching element is provided that bridges the Zena diode, and with this switching element switched to the operating position, the conductor to be tested is placed between the two contact tips by switching on the battery. If present, the continuity test is carried out, or if both contact tips are brought into direct contact with each other, the battery, the acoustic signal generator, the light display element for polarity indication and the light display element for voltage indication corresponding to the battery voltage. This is achieved by means of a test device for displaying voltage and its polarity and for continuity testing, characterized in that the inspection of the test device for the health of the energy storage device and the charging of the capacitor in the energy storage device are carried out.

One preferred embodiment of the test device according to the present invention is as follows: a) Two high-resistance, high-withstand-voltage series resistors are connected in front of a buffer amplifier serving as an input circuit, one of which is connected to the other. The series resistors limit the current caused by the voltage under test. A buffer amplifier is provided which includes an emitter follower consisting of a transistor and an input voltage divider. Therefore, depending on the polarity, the polarity display transistor becomes conductive, and the current circuit of the optical display element for positive polarity display or the optical display element for negative polarity display, or for alternating current voltage, both optical display A current circuit of the element is formed, and at the same time, as the polarity display transistor becomes conductive, the base of the battery circuit switching transistor obtains a potential difference with respect to the positive potential of the battery, so that the battery circuit is switched on, and the polarity display optical display element The current necessary for the light emission is supplied from the battery, and (1) the oscillator is composed of an oscillating syndicator, a resistor, an inductance, and an acoustic signal generator consisting of a ceramic resonator with three electrodes as is well known, and (3) step-up voltage. A voltage amplification circuit (V
Illard type), and power is supplied via an oscillator.

2) The energy storage device consists of a capacitor, a diode that plays the role of peak value rectification, and a switching element that interconnects these capacitors and diodes in the rest position, and the voltage pulse from the booster circuit is rectified in peak value. By accumulating the voltage in the capacitor, the capacitor is charged to the peak value of the voltage pulse.

e) A protection diode and a current control resistor are provided in the connection path between the operating position side terminal of the switching element of the energy storage device and one input end of the buffer amplifier.

Another preferred embodiment of the test device according to the invention is characterized in that the voltage display circuit for stepwise displaying the individual voltage ranges is divided into two voltage display cascade circuits which are supplied with mutually separate display currents, Side voltage range (exceeding 6V, 11
The cascade circuit for the upper voltage range (IIO
The cascade is powered by the booster circuit and is characterized in that both cascades are intermittently opened and closed (ie chopped) at the oscillator frequency to save current.

In addition to the orientation points obtained with known test devices, the test device according to the invention has the advantage of displaying another voltage range above 380 V, for example 660 V. Furthermore, as a particular advantage, the test device according to the invention makes it possible to check the functionality of all display steps before or during the voltage test. For example, during a voltage test, 220
The display elements of all display steps below v emit light, and 3
It is assumed that the display elements of the 80V and 660V display stamps do not emit light. In order to confirm that 380v or 660v is not applied in this case, the opening/closing element S
2 to the operating position and confirm that the display elements for 380V and 660V display emit light. That is, if the switching element S2 is switched into the operating position, the energy storage device is discharged and the discharge current is amplified by the buffer amplifier and switches on the display elements for the 380V and 660V display, so that these display elements emit light. It should be. If one or both of the display elements for 380v and 660V display do not emit light, the display element is faulty, in other words, the voltage to be displayed by the display element is not actually applied. It is known that there may be

In this way, with the test device according to the invention, the possibility of erroneous operation and erroneous display is completely avoided.

Furthermore, in the test device according to the present invention, during a voltage test,
The internal resistance of the test device can be temporarily lowered so that it can be determined whether the voltage source has a low resistance or a high resistance.

In general, this is done to avoid measurement errors even if the circuit under test has high resistance, and to prevent the user from touching one contact tip while a high voltage is being applied to the other contact tip. In order for this to occur, the internal resistance of the test device must be of a sufficiently high value, and in the test device according to the invention it is selected to be, for example, more than 600 Ω. If the input internal resistance is 660Ω, the relationship between the applied voltage and the resulting current is 110 220 380 660 [Veff)0.
17 0.83 0.58 1 (mAeff)
Therefore, the above contact safety is maintained.

On the other hand, when the test equipment is used, for example, to test open/close cubicles or to test the wiring of large-scale equipment, the internal resistance of the test equipment is high, so that the test equipment becomes subject to the test due to electrostatic induction4 or electromagnetic induction. A problem may arise in that the sensor is sensitive to voltage sources other than the voltage source.

Whether the internal resistance of the voltage source is high or low can be determined by the presence or absence of a difference between the display voltage when the internal resistance of the test device is high and the display voltage when it is low, as will be explained in detail later. In making this discrimination, it is desirable that the internal resistance of the test device is temporarily lowered and then raised again after a period of time necessary for the discrimination.

In one embodiment of the invention, the entire circuit in one grip and a high resistance series resistor contained in both grips are combined to temporarily reduce high internal resistance. and a self-heating time constant of at least 1 s (stopping time tBB
) is connected in parallel in a selectively switchable manner. Further detailed embodiments in this case are given in claims 6 to 8.

Thereby, a test device with a high internal resistance can be selectively connected, for example by actuation of a push button, in parallel with a low resistance, for example from 2 to 10 Ω.

Lowering the internal resistance increases the power consumption of the test equipment. For example, if the applied voltage is 50'OV and the internal resistance is 4Ω
In this case, the power consumption is 63W.

This creates a problem in that the temperature inside the test device, ie, the grip containing the circuit, increases.

It is also possible to connect reactances in series instead of resistors, but for safety reasons, we recommend using reactances with V
Not allowed by DE standards.

Using a PTC resistor according to the invention avoids the problem of temperature rise, since after a certain time the resistance automatically increases due to self-heating, limiting the current and thus also the power.

The characteristics of the PTO resistor, such as the rated resistance value RN and self-heating time constant iaB, are based on the German standard VDE44080 (197
(December 2016).

In order to suitably set the time constant of the self-heating process, it is advantageous to connect in series with the PTC resistor a resistor with a constant resistance, ie a resistance value that is virtually independent of the temperature. Thereby, it is possible to distribute power between I)To, low resistance, and constant resistance at the moment of switch-on, and change the time until I)TO, low resistance, becomes high resistance due to self-heating, and the current is reduced.

The time constant of the self-heating process is influenced by the volume of the PTC resistor. In order to achieve the desired time constant, the PTC resistor must be relatively large, eg, 10a diameter and 26w thick.

Commercially available P with a small volume (for example, diameter 5 mm, thickness 1 mm)
TO resistors are cheap and of good quality, but they develop a high resistance so quickly (within a few milliseconds) that the user does not have enough time to determine whether the internal resistance of the voltage source is high or low. . In an advantageous embodiment of the invention, by connecting a constant resistor in series with the PTO resistor, the time constant of the self-heating process can be set to give the user a reading time of several seconds.

In order to further reduce the value of a load resistor consisting only of a PTO resistor or a load resistor in which a PTC resistor and a constant resistor are connected in series, several such load resistors may be connected in parallel.

In one preferred embodiment of the invention, the internal resistance is 80
Rated resistance (RN) 1.5 for 0 or 660 Ω
A PTC resistor of kΩ and at least one constant resistor connected in series for a total of 12 Ω is used.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

In FIG. 1, grip 1 and grip 2 are connected by a cable 3. Grip l has contact tips 4 and 1
The grip 2 is equipped with a contact tiller 5. In FIG. 3, grips 1 and 2 are shown within a dashed box.

The cable 3 is provided with a shield 6.

The grip l contains only a high-resistance series resistor R30 connected after the contact tip 4 and will be referred to below as the test grip 1. On the other hand, the grip 2 with the contact tip 5 contains in its interior a high-resistance series resistor RO and the overall circuit 18, and also an indicator element LED 1.
It is also provided with an LED 9 and two pushbutton switches S1 and S2, which will be referred to below as display grip 2. The display grip 2 further includes a battery Bl.
Contains case G containing . This case is described in German Patent No. 2,756,830 (see also US Pat. No. 4,210,862).

Both the test grip 1 and the display grip 2 are provided with collars 7 and 8 according to the standards of the test device.

These collars are intended to prevent the user of the test equipment from coming into contact with the circuit under test. Display grip 2
The recess 9 is provided at a position where the display can be easily viewed by the user while grasping the display grip using the recess.

The pushbuttons of the switches Sl and S2 are arranged at positions where they can be easily operated with the thumb when the display grip 2 is grasped with the right hand. In addition, the display elements LEDI to LED9
I! on the surface of the display grip 20 so that it is not covered by your fingers or the balls of your fingers. It has been ldi'd.

The display grip 2 is shown in its wide side in FIG. The display grip 2 has a flat shape, and its thickness is only about a width.

The test grip 1 may be constructed as a round bar (FIG. 1), or may be constructed flat like the display grip 2, especially if it incorporates components based on the circuit shown in FIG.

FIG. 2 shows a block circuit diagram of the test device, in which the contact tips 4 and 5 forming the inputs are each connected to a buffer amplifier via one high-resistance series resistor FT'30 and RO. The block representing the buffer amplifier also includes circuitry for polarity and lowest voltage range indication.

The current produced by the voltage under test and limited by the high resistance series resistors R30 and RO is amplified by a buffer amplifier;
Switch on battery circuit B and display polarity and minimum voltage range. The buffer amplifier is a cascade circuit E for voltage display.
and F, and the battery circuit B is connected to a cascade circuit E for voltage display and an oscillator C (including an acoustic signal generator as the case may be). Oscillator C supplies power to booster circuit AI. From the booster circuit A1, the energy storage device A2 is charged while the intermediate switch S2 is in the rest position shown in FIG.

When the switch S2 is switched from the rest position to the operating position, the charge stored in the energy storage device A2 is applied to the power side of the buffer-amplifier via the diode D14. As a result, a current flows at the input of the buffer amplifier that is greater than the current caused by the maximum voltage that the test device is to display, so that all display steps illuminate and disappear one after another as the discharge current decays.

Circuit portion A3 includes switch S1. switch S
1 bridges the zener diode D18 in the rest position shown. When switch S1 is switched from the rest position to the operating position, battery circuit B is switched on. In this state, if there is a conductor to be tested between both contact tips 4 and 5, its continuity test is performed, or if both contact tips 4 and 5 are brought into direct contact with each other, a battery, an acoustic signal is generated. The test equipment is inspected for the health of the device Bu, the polarity display light display element, and the voltage display light display element corresponding to the battery voltage, and the capacitor CI in the energy storage device is charged. By returning the switch SL from the operating position to the rest position and then switching the switch S2 from the rest position to the operating position, all display steps are again checked for health. It is a significant advantage of the test device according to the invention that a complete self-check can be carried out in this way.

FIG. 3 shows the overall circuit of a preferred embodiment of a test device according to the invention. A test grip 1 and a display grip 2 are each shown within a dashed frame and are connected to each other by a shielded cable 3 . The circuits of the display grip 2 are each divided into partial circuits 1 to 5 shown within the broken line frames. The partial circuit A is further divided into three partial circuits Al, A2 and A3 in FIG.

As input circuits, high-resistance and high-withstand resistors R30 and BO are connected after the contact tip 4 of the test grip 1 and after the contact tip 5 of the display grip 2, respectively.

The current generated by the voltage under test is connected to a high resistance series resistor R.
3 (limited by J and RO.

This current is applied to a buffer amplifier. The buffer amplifier includes transistors TI and T2 connected as emitter followers. A current limited by high-resistance series resistors R30 and Ro is applied to these emitter followers via input voltage dividing resistors R1 and R2 or R3 and R4, so that depending on the polarity of the voltage under test, transistors T1 or T2 Transistors Tl and T
2 and a full-wave rectifier circuit consisting of Zener diodes D1 and D2.

As a result, the transistor T3 or T4 becomes conductive depending on the polarity of the voltage to be tested, and the +6V display light emitting diode LED2 or the -6V display light emitting diode LP!
A current circuit of JDI is formed, or a current circuit of both light emitting diodes is formed at AC voltage, and at the same time, as transistor T3 or T4 becomes conductive, the base of battery circuit switching transistor T6 creates a potential difference with respect to the positive potential of battery B1. Battery circuit B is switched on by obtaining light emitting diodes LEI111. The current necessary for the LED 2 to emit light is supplied from the battery B1.

The pace of transistor T6 is connected to battery B1 through resistor R7.
In addition, the light emitting diode LEDI,L is connected via the resistor R8.
Connected to ED2. Transistors T3 and T4
Resistors R5 and R6 are connected in front of the bases of , respectively.

The transistor T6 and the resistor R are controlled by the buffer amplifier and are turned on at the same time as the transistor T3 or T4 is turned on.
The oscillator transistor T5 is switched on via 9 and RIO, and the energy stored in the inductance of the circuit part AI during the switch-on process is released via the transistor T5 towards ground.

The resulting voltage pulse causes the acoustic signal generator Bu to
(buzzer) piezoelectric ceramic movement plate lO is the excitation electrode 11
and 12. piezoelectric ceramic imaging,
Due to the elastic return of the plate, the pace of the oscillator transistor T5 is again corrected via the acoustic return electrode 13.

The oscillator C is active and acts non-linearly on the electrodes 11 and 12 of the piezoceramic diaphragm 10 by means of the west terminal circuit (transistor T5), and by means of electro-acoustic feedback, the oscillator C operates at the natural frequency of the piezoceramic diaphragm lO. The inductance L then acts as an energy storage device.

An acoustic signal generator of the type described here is the subject of German Patent Application No. 3018788.

If the input normal pressure applied to the contact tips 4 and 5 is 6V or more and less than 12V, the voltage polarity display light emitting diodes LEDI and LED2 are switched on, and accordingly the battery circuit B and the acoustic signal generator Bu are switched on. Switched on.

Diodes DIO and Dll serve to reduce the voltage division ratio of the input voltage divider consisting of resistors R1 and R2 or R3 and R4 at low input voltages.

When the input voltage is high, transistors T1 and T2 as emitter followers and diodes D12 and D1 serve to increase the positive voltage of one of these transistors.
3 through a voltage divider consisting of resistors RI3°R14 and RI5.

This current proportional to the input voltage provides a sufficient potential across the transistor T10 to cause the transistor TIO to conduct through the constant current source T15.

One shot, oscillator C to coupling capacitor C to save current
A voltage pulse taken out through 4 and limited in amplitude by a zener diode D4 is applied to the pace of a constant current source T15', thereby forming a pulsed current of constant amplitude at the same frequency as the oscillator C, respectively. Light-emitting diode LED3° LED4 or LED5 (for example 1
At 2V, the light emitting diode LED3) can be made to emit light intermittently.

If the input voltage is higher, the voltage drop across the voltage dividing resistor R15 is greater, and the transistor T9 is switched on and the transistor T 9 , ! : The transistor TIO is switched off again due to the differential amplification effect with TIO, so that the light emitting diode LED4 is switched on.

Switching on the transistor T8, which is a voltage display transistor like the transistors T9 and TIO, is as follows.
Similarly, if the input voltage is higher, this is done via resistor R14.

Zena diodes D1 and D2 of the full-wave rectifier circuit also serve as voltage limiting.

Zena diode D5 or D6 prevents the voltage drop from increasing with increasing input voltage once the pace of the corresponding transistor T9 or TIO reaches the threshold voltage, respectively, and limits the operating range of the transistor to a large number of display step (transistor T8 in the example shown)
．． 'Display step by T9 and TIO).

The display steps of 12V, 24V and 5 (IV) are combined into one cascade E and are supplied with current from the battery Bl.

The 110V, 220V, 880V and 660V display steps are combined in another cascade F.

Light emitting diode LED'D of each display step of cascade circuit F
6 to LFiD9 are connected to diodes D8 and D9 and zener diode D when the input voltage is above 110
Full-wave rectifier circuit consisting of I and D2 and Zena diode D
3, which are switched on in a similar principle to the cascade E when the input voltage reaches the respective voltage range.

The voltage divider of the cascade circuit F is the voltage dividing resistor R1, 6, R17°R1
8 and R19.

The function of Zena diode D7 corresponds to that of Zena diodes D5 and D6.

Capacitors CB, 05 and C6 are smoothing capacitors required for AC voltage testing.

Resistor R20 is connected to the emitter of constant current source T16 and the pace of transistor T14.

The resistor R21 is connected before the pace of the constant current source T16.

In the cascade circuit F, the current necessary for the light emitting diode to emit light is supplied from the booster circuit AI with a voltage higher than the battery voltage, and is intermittent at the frequency of the oscillator C.

Thus, oscillator C also acts as a 1,000-bit oscillator to save the current drawn from the battery to make the light emitting diode emit light.

Furthermore, oscillator C is connected to diode D16. through coupling capacitor C2. D17. It serves to feed a voltage multiplier circuit consisting of D19 and D20 and capacitors C7 and C8 to generate a voltage of 40 to 50V higher than the battery voltage of 12V.

The thus boosted voltage is applied to capacitor C1 within energy storage device iA2. When the switch S2 is switched from the rest position to the operating position, the charge stored in the capacitor C1 is transferred to the resistor 12 and the diode D, l4.
is applied to the input side of the buffer amplifier.

The resistor R12 shown within the dashed box in FIG. 4 can be replaced by the circuit shown in FIG. In this case, the charge stored in capacitor C1 is applied via coupling capacitor C9 to the input side of the buffer amplifier via transistor T7 which is chopped at its frequency by oscillator C. As a result, the time required for capacitor 01 to complete discharging is extended.

In either case, a larger current flows to the input of the buffer amplifier due to the discharge of capacitor C1 than the current flowing to the input of the buffer amplifier due to the voltage applied across the contact tips corresponding to the maximum display step.

Therefore, the functional health of all display steps can be checked from the time the discharge is initiated by switching the switch S2 until the discharge is completed. During this inspection, a sound is emitted by an acoustic signal generator.

Resistors R22 and R23 are connected after the cascade E or F.

The switch Sl is bridged by a zener diode D18 in the rest position. In this state the test device is in voltage test mode.

When the switch S1 is switched from the inactive terminal 16 to the active terminal 17, the battery Bl is switched on via the protection diode D15. If a conductor is present between contact tips 4 and 5, its continuity is tested.

If the contact tips 4 and 5 are brought into direct contact with each other, a self-inspection is performed as described above.

The energy storage device is also charged during this self-check.

To reduce the discharge time constant, resistor R11 is connected in parallel to capacitor C1 by switch S2.

In Fig. 4, partial circuit A is further divided into three parts surrounded by dashed lines, and it also shows which part of the other circuits the input/output terminals of partial circuit A are connected to. has been done.

The selection of components used in the circuit (inductances, resistors, capacitors, diodes, zener diodes, transistors, light emitting diodes) is related to the desired voltage range. Its selection can be made without difficulty by a person skilled in the art based on the disclosure of the present invention.

Next, a circuit for temporarily lowering the input resistance will be explained with reference to FIG. A test grip l with a contact tip 4 and an indicator grip 2 with a contact tip 5 are connected to each other by a shielded cable 6. High-resistance series resistor R30 in the test grip and high-resistance series resistor RO in the display grip and the entire circuit 1
8 form a high resistance series circuit.

When the voltage under test is applied between the contact tips and the pushbutton switch 27 is pressed, at least one PTO resistor 19 is connected in parallel to the series circuit described above. This P.T.
A constant resistor 23 is connected in series with the C resistor 19, and
This determines the time constant of the self-heating process.

For even lower load resistance if required, PTO
Other PTO resistors 20, 21 and 22 are connected in parallel to the resistor 19, and a constant resistor 24.2 is connected to the constant resistor 23.
5 and 26 are connected in parallel.

FIG. 7 shows the relationship between load current and time t at various applied voltages.

Curve X is for the case where the applied voltage is 380 cm, and shows that the effective time of the PTC resistor is about 4 seconds.

That is, when the pushbutton switch 27 (FIG. 6) is pressed, the 4.2 Ω resistor is switched on for about 4 seconds and is therefore active, thereby causing a current of 89 mA to flow. 4.2 A resistance of Ω can be obtained, for example, by connecting three resistors in parallel.

Curve Y is for the case where the applied voltage is 220v, and the same < 4
．． It shows that the effective time spans 18 seconds when the 2 kΩ resistor is switched on.

Curve 2 is for the case where the applied voltage is ll0V, and the same < 4
．． It shows that the effective time is more than 20 seconds when the 2 kΩ resistor is switched on.

Generally, the electromotive force U of a voltage source. When measuring with a voltmeter, if the internal resistance of the voltage source is R, and the internal resistance of the voltmeter is RB, then what is indicated by the voltmeter is Uo, not Uo.
@Rz/(Rr + Ttz).

If the internal resistance R of the voltage source is sufficiently smaller than the internal resistance RE of the voltmeter, the voltage indicated by the voltmeter will be approximately U. is equal to , and does not change significantly even if the value of RE is different. That is, such a voltage source can be considered to be a substantially constant voltage source. On the other hand, if the internal resistance R of the voltage source is not sufficiently smaller than the internal resistance RE of the voltmeter, the voltage indicated by the voltmeter will be smaller than Uo, for example, if R = RB, then U. /2, and varies greatly depending on the RBO value.

Further, it can be considered that the voltage source to be measured generally has a low internal resistance. On the other hand, a voltage source that causes a voltmeter to respond by electrostatic induction or electromagnetic induction (a voltage source other than the one being measured) can generally be considered to have a significantly high internal resistance. Therefore, depending on whether the difference between the voltage indicated when the internal resistance of the voltmeter is high and the voltage indicated when the internal resistance of the voltmeter is low is small or large, it is possible to determine whether the indicated voltage is due to the voltage source being measured. It can be determined whether the voltage is caused by another voltage source. This is utilized in the test device according to the invention. That is, the voltage source is determined in the following process.

For example, when testing an AC distribution voltage of 220V,
All light emitting diodes up to 0V will emit light. If the above-mentioned light emitting diode continues to emit light when the push button switch 27 is pressed to temporarily lower the internal resistance of the test device, it is determined that the voltage of 220V is actually caused by the AC power distribution system. On the other hand, initially 220
If V is displayed but when the pushbutton switch 27 is pressed, only light emitting diodes up to 24V emit light, indicating that the 220V voltage is caused by a voltage source with high internal resistance, that is, a voltage source other than the AC power distribution system connection. It is determined that the

Capacitor (22 μF) in component C1 energy storage device A2 in the preferred embodiment
150 V) C2 coupling capacitor C3, 3μF 150V) C3 smoothing capacitor (1μF/35v) C4 coupling capacitor 7 (33
0pF/100V) C5 smoothing capacitor (lμF/35
■') C6 smoothing capacitor (1,8nF) C7 coupling capacitor (47nF) C8 coupling capacitor (47nF) C9 coupling capacitor (selective, see Figure 5) (830
pp) Dl Full-wave rectifier circuit Zena diode (51V)
D2 Full-wave rectifier circuit Zena diode (51V) D3
Zena diode for L threshold voltage formation (13V) D4 Zena diode for pulse height limitation (2,4V) D5 Zena diode for voltage drop limitation (5, I V ) D6
Zena diode (S, S V ) D7 for voltage drop limitation
Zena diode for voltage drop limitation (6,8V) D8 Full-wave rectifier circuit diode (lN4148) D9 Full-wave rectifier circuit diode (lN4148) DIOR1/R2
Diode (lN4148) for reducing the partial voltage ratio of -Dl
l Diode (I
N4148) Dl2. Diode for increasing the closing voltage of TI (IN4148) Dl3 Diode for increasing the closing voltage of T2 (IN4148) Dl4 S2/1
Diode in front of 5 (lN4148) Dl5 Protection diode in front of Bl (1n4148) Dl6 Dl7
．． Dl9. A diode (
For example lN4148) Dl7 'D18. D19. Diode used for boosting together with D20 (for example lN4148) Dl8 Zena diode (24V) in circuit section A3 D
l9 Dl6. Dl7. Zena diode (IOV) used for boosting voltage with D20 D20 Dl8. Dl7. Diode (IN4148) used for boosting with Dl9 L Inductance in circuit part Al (100mH
) LEDI 6V and negative polarity light emitting diode (e.g. Siemens CQ, V 10-5/LD30T
I) IJD26V and positive polarity light emitting diodes (e.g. Siemens cQ, v 10L5/Ln30
■) LED: l 12V light emitting diode (for example, S
iemenscQv 1o-5/LDso■) LED424V light emitting diode (for example Sie+n
enscQv' 10-5/lID3011) LED5
50V light emitting diode (e.g. Siemens CQ
V' 10-5/LD30[) LICD6110V light emitting diode (e.g. Sie
mensOQ, V 10-5/LD3011) LED7220V light emitting diode (e.g. Elie
meneaQV 10-10-57LD3 0. EDg 5sov light emitting diode (for example S
i'emensCQV 10-5/T, D301 [) Light emitting diode for TJD9660V (e.g. 1318
meneC'QV 10-5/LD80M) RO high resistance series resistor 6 (330 to Ω) R, 1 human power partial voltage resistor (iook Ω) R2 human power partial voltage resistor (180 kΩ) R3 human power partial voltage resistor (100 to Ω) R4 Human voltage division resistor (180 Ω) R5 Resistor in front of T3 (47 Ω) R6 Resistor in front of T40 (47 Ω) R7 Resistor in front of T6 (100 Ω) R8 Resistor in front of T6 (3,9 kΩ) R9 Resistor (150 Ω) before RIO of oscillator C RIO
Resistor before T5 of oscillator C (15Ω) R11 resistor (1
50Ω) R12 resistor (optional, see Figure 4) (5,ekΩ) R1
3 display steps 50V voltage dividing resistor (6,8kΩ) R14
Display step 24V voltage divider resistor (8, 2 Ω) R15 Display step 12V voltage divider resistor (100V Ω) R16 Display step 660V voltage divider resistor (s, s kΩ) R17 Display step 380V voltage divider resistor ( 2,4kΩ) R18 display step 220VO voltage dividing resistor (5,1 Ω) R19 display step 110℃ voltage dividing resistor (10Ω) R20T14
Resistor between and T16 (15 Ω) R21 Resistor before T16 (7,5 kΩ) R22 resistor (51 Ω) R23 resistor (68 Ω) R30 high resistance series resistor (330 Ω) R31 resistor (
(Optional, see Figure 5) (100, Q) T1 ≠Mitter follower transistor in buffer amplifier (BO237)
T2 Emitter follower transistor in the low voltage amplifier (BC!237) T3 Transistor for LED2 (
BO237) T4 LEDI transistor (BC
! 287) T5 Oscillator transistor (BO548) T
6 Switch transistor in battery circuit B (B
C! 556) T7 Buffer transistor (selective, see Figure 5) (BC!556) T8 Display step 50V
Transistor (BO237) T9 Display step 2
4V transistor (BO237) TIO display nug f7 L2V (D transistor (BO237) Tll display step 660M) transistor (BC!546) T1
2 Display step asov transistor (BO'5
46) T13 Display step 220Vt7M transistor (BO546) T14 Display step 110V transistor (BO546) T15 Constant current source for cascade E (BO'237) T16 Constant current source for cascade F (BO237)

[Brief explanation of the drawing]

Figure 1 is a diagram showing the appearance of the entire test equipment on a scale of approximately ■:l, Figure 2 is a block circuit diagram for explaining the operating principle of the test equipment, and Figure 3 is an overall view of a preferred embodiment of the test equipment. Circuit diagram: Figure 4 is a circuit diagram showing a part of the circuit in Figure 3.
, FIG. 5 is a circuit diagram showing an alternative embodiment to a portion of the circuit of FIG. 4, FIG. 6 is a circuit diagram for temporarily lowering the input resistance, and FIG. 3 is a graph showing the relationship between load current and applied voltage when the voltage is lowered. l...Test grip, 2...Display grip, 3...Cable, 4, 5...Contact tiller lug, 6...Shield, 7.8...Brim, 9...Dent, 10...・Piezoelectric ceramic diaphragm, 11.12... Excitation electrode, 13...
・Return electrode, 14... S2 rest side terminal, 15...
Operation of S2 (Ill terminal, 16...Sl rest side terminal% 17...81 operating side terminal, 18...Entire circuit in display grip, 19-22...PTC resistance, 2
3-26... Constant resistance, 27... Push button switch, A... Partial circuit, B... Battery circuit, C... Oscillator, D... Buffer amplifier, J P... Voltage display Cascade circuit for G...battery case, AI...boost circuit, A2...
...Energy storage device, A3...Continuity test and self-inspection circuit, Bl...Battery (12V), Bu...
Acoustic signal generator (buzzer), 81. S2...Opening/closing element.

Claims (1)

[Claims] ■) Each one high resistance series connected by a cable (3) and provided with contact tips (4, 5) and connected after the contact tips (4, 5) Resistor (R, 30
, RO), one of these grips (2) has a voltage range (e.g. 6. 12. 24. 50. 110° 220.
380,660. an oscillator (C) capable of driving the optical display elements (I, llCD1 to 9) of the display step assigned to V) and an optionally provided acoustic signal generator (Bu), and both series resistors. The input current limited by (R30, RO) is amplified and the built-in battery (Bl) is switched on. Buffer amplifier (
D) A test equipment including (a) a booster circuit (A1) which is supplied with power by the oscillator (C) and serves to increase the oscillator voltage limited by the battery; It is connected to the output side of the booster circuit (AI) via the element (S2), and this switching element (
An energy storage device (A2), in particular in the form of a capacitor (CI), is provided which is charged by the output voltage of the booster circuit (A1) while S2) is in the rest position; c) energy storage; The switching element (S2), which is in the rest position when charging the device (A2), is connected to the energy storage device (A2).
2) the oscillator (C1), which can be switched to the operating position in order to apply the charge present in the buffer amplifier ('D) to the input side of the buffer amplifier ('D), thereby sequentially checking the health of all display functions of the test device; However, the upper voltage range (IIOV or more)
Display elements (LED6 to I, ED
9) The display current given to the lower voltage measurement range (6v or more,
The display element (LED3) of the test target voltage within
The display current given to L]1CD5) is also connected to the base of the transistor (T15, T16) which is switched on intermittently (that is, chopped) for a short time. A further switching element (81) is provided, which is connected to the battery (Bl) when the switching element (sl) is switched to the operating position.
By switching on both contact tips (4 and 5)
The continuity test is carried out if there is a conductor to be tested between the battery ('') s acoustic signal generator ( , Bu ), optical display element for polarity display (LEDl
and LED 2) and a voltage display optical display element (IJD 3) corresponding to the battery voltage, and a test device is inspected for the health of the voltage display device (IJD 3), and a capacitor (cl) in the energy storage device is charged. Test equipment for polarity indication and continuity testing. 2) A) Buffer amplifier (D) that serves as an input circuit
Two high-resistance, high-voltage series resistors are connected in front of the grip, one of which (RO) is connected to one of the grips (RO).
2), and the other (R30) is housed in the other grip (1) separated by a shielded cable (3), and both series resistors (
RO, R30) limits the current caused by the voltage under test, and an emitter follower consisting of transistors (TI and T2) and a voltage divider (resistors R1 and R2 or R3)
and R4), and
The transistors (TI or T2) are connected to each other depending on the polarity of the voltage to be tested.
) and Zener diodes (DI and D2), the polarity indicating transistor (T3 or T4) becomes conductive, depending on the polarity of the p1 positive polarity. Optical display element for display (L
m, D2) or negative polarity display optical display element (LKJ)
A current circuit is formed for 1) or, in the case of an alternating current voltage, for both light display elements (LEDI and LFiI) 2), and at the same time a polarity display transistor (T3 or T3) is formed.
4), the battery circuit (B) is switched on as the pace of the battery circuit switching transistor (T6) obtains a potential difference with respect to the positive potential of the battery (Bl), and the polarity display light display element emits light. The current required for the battery (
The oscillator (C) generates an acoustic signal, consisting of an oscillation transistor (T5), a resistor (R9 and R10), an inductance (L), and a ceramic resonator with three electrodes (io) as is well known. C) The booster circuit (Al) consists of four diodes (DI6.DI7.
DI9 and D20) and three coupling capacitors (C2,
C7 and C8) and one inductance ('L), and is powered via an oscillator (C). 2) The energy storage device (A2) connects the capacitor (cB) and the diode (DI7) that plays the role of peak value rectification, and these capacitors (ci) and the diode (D) at the rest position.
I7) is connected to the switching element (S2), and the voltage voltage from the booster circuit (A1) is accumulated in the capacitor (CI) by the peak value rectification (diode D17). (CI) is charged to the voltage Harusuno wave peak value. e) A protection diode (DI 4 ) and a current limiting resistor (R12) are provided in the connection path between the operating position side terminal of the switching element (B2) of the energy storage device and one input terminal of the buffer amplifier (D). A test device according to claim 1, characterized in that: 3) A voltage display circuit for displaying individual voltage ranges step by step is divided into two voltage display cascade paths (E+') each supplied with display currents separate from each other;
The cascade circuit (l is supplied from the battery (B1) via the switching transistor (T6) for the lower voltage range (more than 6V, less than 110V), and the upper voltage range (110V
The cascade circuit (F) for the above) is supplied with power from the booster circuit (Al), and both cascade circuits (E, F) are intermittently opened and closed (i.e. chopped) at the frequency of the oscillator (C) to save current. A test device according to claim 1 or 2, characterized in that: 4) The current limiting resistor (R12) between the operating position side terminal of the switching element (B2) of the energy storage device and the protection diode (B14) is connected to the resistor (R31) and the buffer transistor (
T7) and a coupling capacitor (C9), the emitter of the buffer transistor (T7) is replaced by a protection diode (B14), and its collector and one terminal of the resistor (R31) are replaced by a switching element (B2). operating position side terminal (15) and buffer transistor (T7)
4. The test device according to claim 2, wherein the pace is connected to the other terminal of the resistor (31) and to one pole of the coupling capacitor (C9). 5) High-resistance series resistors housed in the entire circuit (18) in the grip (2) and in the grip (2 and l) for the purpose of temporarily lowering the high input resistance (more than 600 ohms) (RO and R30), 200Ω and 5Ω
PTC with a rated resistance RN between
5. The test device according to claim 1, wherein the resistors (19, 20, 21, 22) are connected in parallel so as to be selectively switchable. 6) Each PTC resistor (19, 20; 21.22),
A resistor with a practically constant resistance value (23°24.25.
26) are connected in series, the testing device according to claim 5. 7) The input resistance of the test equipment (RO+R30) is 660Ω
, a selectively switchable PTC resistor (1
9, 20, 21, 22) has a rated resistance value ranging from 200Ω to 5Ω. 8) At least one constant resistance (23,24°25.2
8. Test device according to claim 7, characterized in that 6) has a resistance value between 1 Ω and 15 Ω.