Electrical / electronic circuit and method for detecting the activation of a secondary access point

Abstract

An electrical / electronic circuit for detecting the activation of a secondary access point for controlling or operating an electrical / electronic device, comprising a primary side (P) with a first potential, a secondary side (S) having the secondary access point with a second potential, wherein the second potential exists between two connecting lines, wherein the primary side (P) has an astable multivibrator with a comparator (K) having an impedance-dependent oscillation frequency of an alternating voltage generated by a voltage supply (V), characterized in that the secondary side (S) of the electrical / electronic circuit has a rectifier (G), in particular connected to the two connecting lines, wherein the rectifier (G) is connected in parallel to the primary side (P) with two lines, each connected to a Y-capacitor (C1, C2), in a galvanically isolated manner.wherein a capacitor (C3) is connected in parallel to the rectifier (G), the capacitor (C3) can be bypassed by an auxiliary switch (NS) of the auxiliary station which is to be influenced when actuated, so that when bypassed the resulting oscillation frequency of the astable flip-flop changes as an indicator of the actuation of the secondary access point.

Description

[0001] The invention relates to an electrical / electronic circuit for detecting the actuation of a secondary access point for controlling or operating an electrical / electronic device, comprising a primary side with a first potential, a secondary side having the access point with a second potential, wherein the second potential is between two connecting lines, wherein the primary side has an astable flip-flop with a comparator having an impedance-dependent oscillation frequency of an alternating voltage generated by a power supply.

[0002] Furthermore, the invention relates to a method for detecting the activation of a secondary access point for controlling or operating an electrical / electronic device with such an electrical / electronic circuit.

[0003] Various electrical / electronic circuits for detecting the activation of a secondary access point for controlling or operating an electrical / electronic device are known in the prior art. For the purposes of this invention, secondary access points are understood to be, for example, extensions, binary inputs, or the like.

[0004] DE 10 2020 108 673 A1 discloses a circuit with an astable multivibrator and a comparator. The oscillation frequency of the astable multivibrator is influenced by a temperature-dependent resistor. Detection of the switching process is not disclosed.

[0005] From DE 196 25 408 B4 a circuit for the potential-free transmission of an alarm signal has become known, which alarm signal is generated at the output of a comparator.

[0006] DE 38 30 265 C1 discloses a circuit with an astable flip-flop and a threshold stage which, in the event of a fault, outputs an alarm signal via a downstream isolation stage with galvanic isolation.

[0007] A disadvantage of previously known electrical / electronic circuits for detecting the activation of a secondary access point is that, although they can provide a potential on the secondary side that is galvanically isolated from the primary side, this requires an additional power supply on the secondary side, in particular a space-consuming and expensive opto-coupler and / or a power supply unit.

[0008] Based on this discussed state of the art, the invention aims to create an electrical / electronic circuit for detecting the actuation of a secondary access point, which is designed to be as space-saving and cost-effective as possible.

[0009] This problem is solved by an electrical / electronic circuit for detecting the actuation of a secondary access point, wherein the secondary side of the electrical / electronic circuit has a rectifier, in particular connected to the two connecting lines, wherein the rectifier is connected in parallel to the primary side with two lines each connected to a Y-capacitor, galvanically isolated, wherein a capacitor is connected in parallel to the rectifier, the capacitor can be bridged by an auxiliary switch of the auxiliary switch which is to be influenced when actuated, so that when bridged the resulting oscillation frequency of the astable flip-flop changes as an indicator of the actuation of the secondary access point.

[0010] The core concept of the invention is that the primary side comprises an astable multivibrator with a comparator whose oscillation frequency is impedance-dependent and corresponds to an alternating voltage generated by a power supply. The secondary side is designed to be bypassable, so that when the secondary access point is bypassed, the resulting oscillation frequency of the astable multivibrator changes, indicating that the secondary access point has been actuated. In the electrical / electronic circuit according to the invention, the detection of the actuation of a secondary access point for controlling or operating an electrical / electronic device avoids the need for a space-consuming and expensive optocoupler and / or a power supply. For this purpose, the secondary side of the electrical / electronic circuit includes a rectifier, which is connected, in particular, to the two connecting leads.Such a rectifier can be implemented, for example, as a bridge rectifier, a single-pulse center-tap rectifier, or a two-pulse center-tap rectifier. In the electrical / electronic circuit according to the invention, the rectifier is connected to the primary side in parallel via two lines, each connected to a Y-capacitor, providing galvanic isolation. A particular advantage of this configuration is that it achieves galvanic isolation that meets SELV requirements.

[0011] A particularly clever aspect of the invention is the parallel connection of a capacitor to the rectifier. This capacitor can be bypassed by an auxiliary switch of the secondary switch, the position of which is controlled by the switch. When the capacitor is bypassed, the resulting oscillation frequency of the astable multivibrator changes, indicating that the secondary access point has been activated. The detection of this change in oscillation frequency is preferably achieved using a microcontroller connected to the astable multivibrator. To amplify the signal, i.e., the change in the resulting oscillation frequency, a resistor is preferably also connected in parallel to the rectifier, in addition to the capacitor.

[0012] This advantageously creates an electrical / electronic circuit for detecting the activation of a secondary access point for controlling or operating an electrical / electronic device, which does not require an additional power supply on the secondary side, thus eliminating the need to use a space-consuming and expensive opto-coupler and / or a power supply unit.

[0013] According to a particularly preferred embodiment of the electrical / electronic circuit for detecting the activation of a secondary access point, the capacitor has a capacitance of at least 20 nF, and in particular at least 100 nF. This makes the change in the oscillation frequency particularly easy to detect by the astable multivibrator with the comparator.

[0014] According to a particularly preferred embodiment of the electrical / electronic circuit for detecting the activation of a secondary access point, a resistor, in particular a resistor of less than 100 kΩ, is connected between the two Y-capacitors. This offers the advantage that the resistance provided in an auxiliary line, for example 50 kΩ, is considerably smaller than the resistance of an open switch or the auxiliary line itself. This minimizes the influence of environmental factors on the frequency at the flip-flop.

[0015] Furthermore, the invention relates to a method for detecting the actuation of a secondary access point for controlling or operating an electrical / electronic device with an electrical / electronic circuit according to the invention, comprising the steps: - Relative detection of the impedance-dependent change in oscillation frequency by actuating the auxiliary switch of the access point, - Identification as activation of the secondary access point when the vibration frequency change assumes a definable value.

[0016] In the inventive method, the impedance-dependent change in oscillation frequency is detected in a first step by actuating the auxiliary switch of the access point.

[0017] Subsequently, the secondary access point is identified as being activated when the vibration frequency change reaches a definable value. For example, a vibration frequency change in the range of approximately 1 kHz to 50 kHz within a time period of 50 ms to 500 ms can be identified as activation. Such values ​​lead to a particularly reliable interpretation of the secondary access point activation.

[0018] The invention is described below with reference to the accompanying figures and an exemplary embodiment. It shows: Fig. 1: A circuit diagram of a possible embodiment of the electrical / electronic circuit according to the invention for detecting the actuation of a secondary access point.

[0019] Fig. Figure 1 shows a circuit diagram of a possible embodiment of the electrical / electronic circuit according to the invention for detecting the actuation of a secondary access point.

[0020] A primary side P with a first potential and a secondary side S with a second potential, which includes the secondary access point, are identifiable. The second potential is located between two connecting lines. Furthermore, the primary side P comprises an astable multivibrator with a comparator K having an impedance-dependent oscillation frequency of an alternating voltage generated by a power supply V. In the illustrated embodiment of the invention, the secondary side S comprises a rectifier G connected to the two connecting lines, which is implemented here as a bridge rectifier comprising diodes D1-D4. Galvanic isolation between the primary side P and the secondary side S is achieved here by means of the two Y-capacitors C1 and C2. Power is supplied by a power supply V on the primary side P. The remote control can be connected to the remote control connection lines NS_A and NS_B, respectively.

[0021] A capacitor C3 and a resistor R5 are connected in parallel to the rectifier G. Both capacitor C3 and resistor R5 can be bypassed by an auxiliary switch NS of the secondary access point, the position of which is influenced by actuation. Bypassing the switch, the resulting oscillation frequency of the astable multivibrator changes, indicating the actuation of the secondary access point. Bypassing the switch NS, the resulting resonant circuit, and thus its impedance-dependent oscillation frequency, is altered, as the influence of capacitor C3 and resistor R5 can be switched on or off by actuating the auxiliary switch.

[0022] A particularly advantageous feature of the electrical / electronic circuit according to the invention for detecting the activation of a secondary access point is that the capacitor C3 has a capacitance of at least 20 nF, and in particular at least 100 nF. This ensures that the capacitance of this capacitor C3 is significantly greater than the capacitance of the conductors themselves in a 100-meter-long multi-core cable. This is what makes the use of long extension cables possible in the first place.

[0023] The invention is described using an exemplary embodiment. Without departing from the scope of the applicable claims, numerous other possibilities for implementation would arise for a person skilled in the art, without the need to explain these in detail within the scope of these statements. Reference symbol list C capacitor D diode G rectifier NS auxiliary switch NS_A,B Extension Line K comparator P Primary page R resistance S Secondary page V Power supply

Claims

[1] Electrical / electronic circuit for detecting the actuation of a secondary access point for controlling or operating an electrical / electronic device, comprising a primary side (P) with a first potential, a secondary side (S) having the secondary access point with a second potential, wherein the second potential is between two connecting lines, wherein the primary side (P) has an astable multivibrator with a comparator (K) having an impedance-dependent oscillation frequency of an alternating voltage generated by a voltage supply (V), characterized by, that the secondary side (S) of the electrical / electronic circuit has a rectifier (G), in particular connected to the two connecting lines, wherein the rectifier (G) is connected in parallel to the primary side (P) with two lines each connected to a Y-capacitor (C1, C2) in a galvanically isolated manner, wherein a capacitor (C3) is connected in parallel to the rectifier (G), the capacitor (C3) can be bridged by an auxiliary switch (NS) of the auxiliary switch which is to be influenced when actuated, so that when bridged the resulting oscillation frequency of the astable flip-flop changes as an indicator of the actuation of the secondary access point. [2] Electrical / electronic circuit according to claim 1, characterized by , that the capacitor (C3) has a capacitance of at least 20 nF, in particular at least 100 nF. [3] Electrical / electronic circuit according to claim 1 or 2, characterized by, that the rectifier (G) includes a bridge rectifier. [4] Electrical / electronic circuit according to any one of claims 1 to 3, characterized by , that the rectifier (G) comprises a single-pulse center-tap circuit or a two-pulse center-tap circuit. [5] Electrical / electronic circuit according to any one of claims 1 to 4, characterized by that the secondary access point has a branch. [6] Electrical / electronic circuit according to any one of claims 1 to 5, characterized by , that a resistor (R6) is connected between the Y capacitors (C1, C2). [7] Electrical / electronic circuit according to any one of claims 1 to 6, characterized by , that a resistor (R5) is connected in parallel to the rectifier (G). [8] Method for detecting the actuation of a secondary access point for controlling or operating an electrical / electronic device with an electrical / electronic circuit according to any one of claims 1 to 7 for detecting the actuation of a secondary or supplementary access point for controlling or operating an electrical / electronic device comprising the steps: - Relative detection of the impedance-dependent change in oscillation frequency by actuating the auxiliary switch (NS) of the access point, - Identification as activation of the secondary access point when the vibration frequency change assumes a definable value.

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