DE2808869A1 - Electric tester with acoustic signalling - has two voltage sources connected by opposite polarity terminals to oscillator - Google Patents

Abstract

The tester signals acoustically resistance and continuity. It consists of a d.c. voltage source (1), whose negative terminal (-) is connected to an electronic oscillator(3), and its other terminal(+) to one of two set terminals (5, 6) between which the test circuit is produced. The second terminal (6) is connected to the second terminal of the oscillator (3). A second d.c. voltage source (2) terminal (+) is connected to the oscillator (3) terminal to which the first voltage source (1) is also connected. Its other terminal (-) is connected through a resistor (4) to the terminal (6). The electronic oscillator controls an amplifier (7).

Description

Patent description

Electrical test device with acoustic analog display for resistance and passage.

Field of application The invention relates to an electrical test device with acoustic analog display for resistance and passage, according to dFt upper handle of claim 1.

With such a tester it is possible to test or not to stand electrical Connections, high or low electrical resistance in such advertisements, If they exist outside the device, they can be tested, whereby the test device is bribed a connection, the presence of a resistance something that can be perceived by humans emits acoustic signal.

Such testers are, for example, continuity testers, line testers or called a test buzzer.

Purpose The test device is used in the construction of electrical systems the energy, Ferneelde-, @ e.J- and control technology used to the Uerbindungen to check between the system parts before they are put into operation.

It is also used for troubleshooting such systems. This is also used Device for troubleshooting electrical and electronic equipment.

state of the art test equipment that provides an audible quantitative analog display Use for resistors or passage are in the DT-PS 16 16 û91 and DT-AS 23 04 211 included. In both cases it is mentioned - that the pitch of the acoustic Signal of the size of the resistance to be tested in the test circuit depends. The determination of the magnitude of this resistance becomes human Ability to estimate pitches left. In 5 patent 3284 707 also indicates the pitch opposite to the resistance value.

In addition, a circuit is specified in DT-PS 23 11 012 that it enables the relative size of resistances to be determined by comparing tones.

Criticism of the Prior Art When Testing Electrical Contractions on good continuity it is often important to recognize that the resistance of the tested prevention does not exceed a - usually quite small - amount. this is in itself with the comparison method according to DT-PS 23 11 012 m (.; r1ich, insowit d: s tester used a sufficient frequency difference between the two required Limits generated. But even if this is the case, precise recognition is required an expenditure of time that is particularly annoying when checking through such multi-core labels.

Task The inventor bases the task on exceeding a preferably very low resistance in the test current circuit between the To make test poles clearly and clearly recognizable acoustically, for example by the simple The distinction made possible by this is indicated by a tone and the statement that the resistance in the test circuit is higher than permissible No test tone is displayed.

Solution This object is achieved according to the invention by the in the characterizing Part of claim 1 specified features solved.

Further embodiment of the invention In a further embodiment of the Invention is the connection from the second direct current source to the second test pole made interruptible by a switch. When the switch is open, the Electronic oscillator as continuity and resistance tester in one area usable solely by its internal dimensioning and the properties of the reinforcing Elements is given.

this switch is conveniently housed in the handle, which carries the test electrode of the second test pole, both actuation by Push button as well as the movably built-in test electrode can.

Another embodiment of the invention is an amplifier, the possibly weak output signals of the electronic oscillator amplified that an electro-acoustic converter (loudspeaker) is controlled so far can be that the volume is sufficient for a good perceptibility.

The energy required for this is then provided by the series-connected DC sources applied.

Achievable Advantages The advantages that can be achieved with the invention exist in that the assessment of whether a tested electrical connection has a specific Resistance value, is made possible very easily and quickly. Just those of the tested connections, the resistances of which are below the limit value the electronic oscillator vibrate and thus produce a sound that goes through the electro-acoustic converter is made audible to humans.

Because the circuit that creates the sharp demarcation, can be made switchable with a single contact, there is the advantage that that tests can also be carried out in which the sharp delimitation interferes would. This makes the device more versatile.

The switch also enables the device to function properly to examine if it remains silent during an examination and there are doubts about it, whether the tested connection has a resistance above the limit value or the device fails, for example due to exhausted power sources.

In addition, the switch can also be used to determine whether the dumb laiban only from a resistance in the test current circuit which is only slightly above the limit value or the test circuit is interrupted, so there is no test circuit at all.

Description of an exemplary embodiment That shown in FIG Embodiment of an electrical test device with analog display for resistance and passage consists of an electronic oscillator (3), which is an astable Toggle circuit or multivibrator is carried out.

The oscillation frequency is mainly determined by the basic resistance 32 and 33 as well as by the capacitors 34 and 35 determined. As soon as the test poles (5) and (6) are connected to one another directly or via a resistor, angled Current from the positive pole of the source (1) via (5), the test circuit according to (6;, via the Resistance (38) flow, which is then always through the transistors (35) to the negative pole the source (1) arrives when the transistor (37) is ghosted. In the period in the transistor (37) is conductive, the current flows from the positive pole of the source (1) through the resistor (42), the transistor (37) directly to the negative pole the source (1).

The current through the resistor (42) leaves a voltage between the emitter and the base of the transistor (41), which causes the base current, and the transistor (41) conductively controls. So that a current flow from the positive pole of the source (1) via the Emitter-collector path of the transistor (41) and the loudspeaker (44) to the negative pole the source (2) possible. Since the sources (1) and (2) are connected in series, the current through this circuit is driven by a higher voltage and the speaker (44) is more excited than when it - instead of the resistor (42) - in the circuit of the oscillator traqsistor (37) would be.

The oscillator will work as long as the voltages on the transistor (36) allow this; that is, there is a limit value for the resistance in the test circuit between the test poles (5), (6), at which the essential part of the voltage of the source (1) falls off this. This limit is a few thousand ohms; he is from depending on the model deviations of the transistors.

If the switch (46) is closed, the result described in claim 1 and Fig. 1 shown arrangement. As long as there is no test circuit between the test poles (5) and (6), flows through the resistor (4), the safety fuse (45) and no current through the closed switch (46), since the negative pole of the source (2) and the transistors and the diode (39) have opposite polarity are.

If a test circuit is formed between test poles (5) and (6), when the switch (46) is closed, a voltage divider is created from the resistor the test circuit and the resistor (4) is formed. (The resistance of the fuse be negligible.) The current in this voltage divider is from both sources (1), (2) driven, where the sum of their voltages is effective.

The potential at the test pole (6) - is now dependent on the divider ratio. Because the resistor (4) has a fixed value or is set to a certain world is, the potential at the test pole (6) depends only on the resistance of the test circuit between the test poles (5) and (6). It becomes positive towards the connection point (12) be between sources (1) and (2) as long as the resistance is in the test circuit is small compared to the resistor (4); and it becomes negative towards the connection point (12) if the resistance in the test circuit is greater than the resistance is (4). It follows that the electronic oscillator (3) only work can, if the resistance in the test circuit is less than the resistance (4), so the test pole (6) is at a positive potential opposite the connection point (12) of the two sources (1) and (2).

The resistor (38) and the Zener diode (39) form a protective circuit against external voltage according to DT-PS 23 01 742, the fuse (45) takes over this Protection for the circuit that is closed by switch (46).

Claims (4)

P a t e n t a n s p r ü c h e 1. Electrical test device with acoustic Analog display for resistance and continuity, consisting of a direct current source (1) whose one pole (-) is connected to an electronic oscillator (3) and whose other pole (+) leads to one of two test poles (5, 6), 7 those of Test circuit is formed and the second test pulse (6) with the second connection of the electronic oscillator is connected, characterized in that a zueite Direct current source (9) with the pole of opposite polarity (+) on the connection of the electronic oscillator (3) is connected, to which also the first direct current source (1), the other pole (-) of the second DC power source (2), however, via one Uldersand (4) is connected to the second test pole (6), which is connected to the other Connection to the electronic oscillator (3) is connected. 2. Electrical test device according to claim 1, characterized in that that in the circuit of the second direct current source (2) a switch (46) is inserted is. 3. Electrical test device according to Amsmruch 1., characterized in that that the electronic oscillator (3) controls an amplifier (7) whose output circuit from the two series-connected direct current sources (12 2) we are fed. 4. Electrical test device according to claim 1 and 2, characterized in that that the switch is built into the handle of a test electrode that is connected to the second Test pole (6) is connected and that this switch is either with a push button or is actuated by the test electrode, which for this purpose is movable in the Handle is stored.