AUDIO SIGNAL MATCHING DEVICE WITH PREVENTIVE ELECTRICAL SAFETY MONITORING FUNCTION

Abstract

The utility model pertains to electrical engineering and sound amplification technology, specifically to devices for switching, balancing, and galvanic isolation of audio signals (DI boxes, audio splitters) used to connect sound equipment at concert and rehearsal venues. An audio signal matching device with a preventive electrical safety monitoring function comprises a housing, input and output audio signal interfaces, a ground loop interrupt switch connected between a first ground bus of the input path and a second ground bus of the output path, and is additionally equipped with a hazardous potential indication circuit connected in parallel to the contacts of the aforementioned ground loop interrupt switch and configured to provide a visual alert upon the occurrence of a potential difference between the first and second ground buses when the switch is open.The technical result is the automatic detection of a dangerous difference in electrical potentials between independent grounding circuits of audio equipment and the immediate visual alerting of technical personnel before physical contact with the emergency equipment. 2 clauses, 1 fig.

Description

[0001] Technical field

[0002] The utility model relates to the field of electrical engineering and sound amplification technology, specifically to devices for switching, balancing and galvanic isolation of audio signals (DI boxes, audio splitters) used to connect sound equipment at concert and rehearsal venues.

[0003] Technology Level

[0004] Audio signal matching devices (DI boxes) are known that contain input and output interfaces, galvanic isolation elements, and a ground loop break switch (Ground Lift function) designed to eliminate electromagnetic interference of 50 Hz background noise that occurs due to the formation of “ground loops” between different equipment (see https: / / art-complex.ru / product / dbx-di1-5254 / ).

[0005] A drawback of known devices is the lack of ability to monitor the electrical potential on the ground busbars. When the ground lift switch is activated, the device eliminates the audio loop hum, but makes the system "blind" to emergency situations. If the sound equipment connected on stage (guitar amplifiers, keyboards, effects devices) has a faulty power supply, an ungrounded switching power supply, or is connected to a different phase of the electrical network with a ground loop fault, a dangerous potential difference (up to 110-220 V) will arise between the body of this equipment and the input ground bus of the matching device. If the artist or technical personnel simultaneously touches this emergency equipment and elements connected to a reliably grounded mixing console (e.g., a vocal microphone), an electric shock will occur.At the same time, the known coordination device does not inform personnel in any way about the existing pre-emergency threat.

[0006] Disclosure of the essence of the utility model

[0007] The technical problem that the claimed utility model is aimed at solving is the elimination of the aforementioned deficiencies and the provision of prompt preventive visual control of the electrical safety of the switching field on stage.

[0008] The technical result is the automatic detection of a dangerous difference in electrical potentials between independent grounding circuits of audio equipment and instant visual alerting of technical personnel before the moment of physical contact of a person with the emergency equipment.

[0009] The specified technical result is achieved in that the audio signal matching device, comprising a housing, audio signal inputs and outputs, a ground loop break switch connected between the first (local input) ground bus and the second (main output) ground bus, according to the utility model, is additionally provided with a circuit for preventive indication of hazardous potential, connected in parallel to the contacts of the said ground loop break switch, wherein the indication circuit is configured to activate and glow under the action of a leakage current caused by the potential difference between the first and second ground buses when the switch is open.

[0010] The preventive indication circuit consists of a series-connected LED indicator and a current-limiting resistor, the value of which is selected based on the condition of limiting the leakage current through the LED to values ​​that are safe for humans (no more than a few milliamps) when a 220 network potential appears on the bus.

[0011] In addition, an RC circuit consisting of a parallel-connected capacitor and resistor is connected in parallel with the ground loop break switch and the preventive indication circuit, providing high-frequency shunting and equalization of static potentials between the ground buses.

[0012] Brief description of drawings

[0013] Fig. 1 shows the basic electrical circuit diagram of the preventive electrical safety monitoring unit of the audio signal matching device.

[0014] Implementation of a utility model

[0015] The device contains a first ground bus (local backline ground) GND1, a second ground bus (main ground of the mixing console) GND, and a switch SW2, which closes or opens the GND1 and GND buses. Connected in parallel to switch SW2 is an indicator circuit containing LED2 and a current-limiting resistor R42. Also connected in parallel to the switch is an RC filter circuit consisting of capacitor C12 and resistor R7.

[0016] The device operates as follows.

[0017] When connecting audio equipment to the device's interfaces, the first ground bus GND1 is connected to the body of the device on stage (signal source), and the second ground bus GND is connected through the shield of the balanced XLR cable to the ground circuit of the mixing console or stagebox.

[0018] In normal operation, when switch SW2 is closed, the GND1 and GND buses are connected directly. Interference current flows freely to the common ground, and there is no potential difference between the buses. LED2 is short-circuited by the contacts of switch SW2; no current flows through it, and the indicator is off.

[0019] In ground loop break mode, when switch SW2 is opened by the user to eliminate audio noise, the direct connection between GND1 and GND is broken. Static equalization and high-pass filtering are provided by C12 and R7.

[0020] In the event of an emergency on stage (lack of grounding on the signal source, insulation breakdown, or potential leakage from the filters of the switching power supply to the device body), a dangerous alternating voltage appears on the GND1 bus relative to the stably grounded GND bus of the mixing console.

[0021] Under the influence of the resulting potential difference, an emergency current flows through the indicator circuit along the following path: GND1 bus - LED2 - current-limiting resistor R42 - GND bus. LED2 begins to emit light, signaling technical personnel of the presence of a dangerous potential on the stage equipment and the need to restore the standard grounding of the devices. Current-limiting resistor R42 (with a rating of, for example, 10 kOhm) prevents the flow of life-threatening current through the device and prevents false triggering of the stage protection systems (RCDs) during monitoring. After personnel eliminate the cause of the malfunction and restore the equipment grounding, the potential difference disappears and LED2 goes out.

Claims

1. An audio signal matching device with a preventive electrical safety monitoring function, comprising a housing, input and output audio signal interfaces, a ground loop break switch connected between the first ground bus of the input path and the second ground bus of the output path, characterized in that it is additionally provided with a hazardous potential indication circuit connected in parallel to the contacts of the said ground loop break switch and configured to provide a visual warning when a potential difference occurs between the first and second ground buses in the open state of the switch.

2. The device according to paragraph 1, characterized in that the circuit for indicating hazardous potential is made in the form of a series-connected LED and a current-limiting resistor.

3. The device according to item 1, characterized in that a filtering RC circuit consisting of a capacitor and a resistor connected in parallel is connected in parallel to the ground loop break switch.

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