CN102097253A - Control circuit - Google Patents

Abstract

The present invention provides a control circuit, including a signal control source, a capacitor charging and discharging circuit, an actuator, and a functional circuit connected to the capacitor charging and discharging circuit, wherein the signal control source provides current for the capacitor charging and discharging circuit, The capacitor charging and discharging circuit is used to charge and discharge the actuator according to the control of the functional circuit. Through the control circuit provided by the embodiment of the present invention, the drive control of actuators such as single-coil bistable (magnetic latching) relays can be realized through a hardware circuit composed of a small number of simple discrete components, such as driving them, Or turn off the circuit of the relay when the voltage crosses zero.

Description

Control circuit

technical field

The invention relates to the field of electricity, in particular to a control circuit.

Background technique

Most of the relays currently on the market are monostable. When the coil of a monostable relay is excited, the contact moves. There are two types of coils and double coils. When the coil is excited, the contact will act. After the coil is de-energized, the contact will remain in this state. To return the contact to its original state, it is necessary to apply reverse excitation to the single-coil type coil, or Excitation is applied to the double-coil type return coil. The bistable (magnetic latching) relay can maintain the state after the coil is de-energized and does not need to provide additional maintenance energy. The use of this type of relay has low power consumption and long service life, effectively saving energy. Therefore, from the perspective of environmental protection and energy saving, it is the future development trend to choose the control method of bistable (magnetic latching) relay.

The use of bistable (magnetic latching) relays saves energy, but the control of bistable (magnetic latching) relays is more complicated than that of ordinary relays. The driving coil of the bistable (magnetic latching) relay has positive and negative poles. By default, a positive pulse of a certain width is added to the positive pole of the bistable (magnetic latching) relay. The bistable (magnetic latching) relay ) The state of the relay will change from the open state to the closed state, and a negative pulse of a certain width is added to the positive pole of the bistable (magnetic latching) relay to the negative pole, and the state of the bistable (magnetic latching) relay will be Change from the closed state to the open state (if the original state is open and closed, the state will not be changed). The pulse width and pulse amplitude required by different bistable (magnetic latching) relays can be found from the technical manuals of different relay manufacturers.

In the prior art, the MCU is usually used to output pulse signals or a similar bistable (magnetic latching) circuit is composed of complex discrete components to drive the bistable (magnetic latching) relay. Such a circuit is more complicated and costly. higher. In the prior art shown in Figure 1, the single-coil bistable (magnetic latching) relay is driven by a single-chip microcomputer programming instruction to output a positive or negative pulse signal of a certain width and amplitude, but due to the use of a single-chip microcomputer for control, the circuit The cost is relatively high.

In order to reduce the interference on the switch and the impact on the equipment, protect the contacts of the relay, and usually turn off the relay when it crosses zero. When using a bistable (magnetic latching) relay circuit, the zero-crossing signal is often used to turn off the relay at zero-crossing

In the prior art, the zero-crossing is usually achieved by means of transformer isolation or photocoupler isolation. The zero-crossing signal is read by the single-chip microcomputer, and the relevant commands are controlled to output to realize the switching circuit or frequency detection. As shown in Figure 2, the transformer is used as the Isolation, through the single-chip microcomputer to detect the trip voltage of the triode and then output instructions to control the device to work near the zero crossing point. However, due to the use of single-chip microcomputers and transformers, the implementation process is more complicated and the cost is higher.

Therefore, there are few solutions in the prior art that can realize zero-crossing control of bistable (magnetic latching) relays at a relatively low cost.

Contents of the invention

The present invention aims to provide a control circuit that can be used to drive or control the actuator when the voltage crosses zero.

In order to achieve the above object, the present invention proposes a control circuit, including a signal control source, a capacitor charging and discharging circuit, an actuator, and a functional circuit connected to the capacitor charging and discharging circuit, wherein the signal control source is the capacitor charging and discharging circuit. The discharging circuit provides current, and the capacitor charging and discharging circuit is used to supply power to the actuator according to the control of the functional circuit.

Preferably, the capacitor charging and discharging circuit includes a capacitor, a first diode, a first NPN transistor, and a base bias resistor that supplies current to the base of the transistor, wherein the anode of the actuator is connected to the capacitor The negative pole of the executive element is connected to the emitter of the triode, the collector of the triode is connected to the positive pole of the capacitor, and the base bias resistor is connected in series between the base of the triode and the capacitor, The anode of the first diode is connected to the negative pole of the actuator, and the cathode is connected to the base of the triode.

Preferably, the functional circuit is a pumping circuit, including a first thyristor and a first Zener diode, wherein the cathode of the first thyristor is connected to the ground wire, and the control electrode of the first thyristor The anode of the first zener diode is connected, the cathode of the first zener diode is connected with the signal control source and the anode of the capacitor, and the anode of the first thyristor is connected with the cathode of the first diode.

Preferably, a current limiting resistor is connected in series between the first zener diode and the signal control source, and/or, between the first zener diode and the cathode of the first thyristor Connect an anti-interference resistor in series.

Preferably, the functional circuit is a voltage zero-crossing circuit, including a photocoupler and a switch circuit. When there is no zero-crossing signal input at the input terminal of the photocoupler, the switch circuit will not be triggered to conduct; When the zero signal is input, the trigger switch circuit is turned on, and the switch circuit forms a discharge circuit with the capacitor charging and discharging circuit and the actuator.

Preferably, the switch circuit includes a second NPN transistor (Q22), a third NPN transistor (Q23) and a second thyristor (SCR2), wherein the collector of the third NPN transistor (Q23) is connected to the second NPN transistor ( The base of Q22) is connected, the emitters of the two are connected together to the anode of the second thyristor (SCR2), and the collector of the second NPN transistor (Q22) is connected to the control electrode of the second thyristor (SCR2). , the cathode of the second thyristor (SCR2) is connected to the negative coil (b) of the relay.

Preferably, a second diode (D22) is connected in antiparallel between the anode and cathode of the second thyristor (SCR2).

Preferably, a resistor (R25) is connected in series between the collector of the optocoupler output transistor and the positive pole of the capacitor;

A resistor (R24) is connected in series between the base of the third NPN transistor (Q23) and the positive pole of the capacitor, and the base of the third NPN transistor (Q23) is also connected to the output terminal (16) of the photocoupler (U1). The emitters of the three NPN transistors (Q23) are connected to the anode of the second thyristor (SCR2), and the collectors of the third NPN transistors (Q23) are connected to the positive electrode of the capacitor through a resistor (R24);

The base of the second NPN transistor (Q22) is connected to the collector of the third NPN transistor (Q23), the emitter of the second NPN transistor (Q22) is connected to the anode of the second thyristor (SCR2), and the second NPN transistor (Q22) ) collector is connected to the control electrode of the second thyristor (SCR2), and a resistor (R23) is connected in series with the positive electrode of the capacitor.

Preferably, a resistor (R22) is connected in parallel between the collector and emitter of the second NPN transistor (Q22).

Preferably, the input terminal (1) of (U1) is connected to the fire wire of the actuator through a current limiting resistor (R26), and the other input terminal (2) is connected to the neutral line, and antiparallel connection between the two input terminals Two diodes, an output terminal (16) of the optocoupler (U1) is the collector of the phototransistor, connected to the base of the third NPN transistor (Q23), and the other output terminal (15) is the emitter of the phototransistor, Connect to the anode of the second SCR (SCR2).

Through the control circuit provided by the embodiment of the present invention, the control of actuators such as driving single-coil bistable (magnetic latching) relays can be realized through a hardware circuit composed of simple discrete components, such as driving them, or A circuit that turns off a relay when the voltage crosses zero.

Description of drawings

The following drawings are only intended to illustrate and explain the present invention schematically, and do not limit the scope of the present invention. in,

Fig. 1 is a kind of driving single-coil bistable state (magnetic holding type) relay circuit diagram in the prior art;

Fig. 2 is a kind of zero-crossing detection circuit diagram in the prior art;

Fig. 3 is a kind of control circuit block diagram in the embodiment of the present invention;

Fig. 3A is the embodiment block diagram of a kind of control circuit of the present invention;

Fig. 3B is the embodiment block diagram of a kind of control circuit of the present invention;

FIG. 3C is a block diagram of an embodiment of a control circuit of the present invention;

Fig. 4 is a circuit diagram of a control circuit embodiment shown in Fig. 3A;

Fig. 5 is a circuit diagram of a control circuit embodiment shown in Fig. 3B;

Fig. 6 is a circuit diagram of an embodiment of the control circuit shown in Fig. 3C.

Detailed ways

In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation manners of the present invention will now be described with reference to the accompanying drawings.

As shown in Fig. 3, the present invention provides a kind of control circuit, can be used for controlling the action of executive element such as single-coil bistable state (magnetic holding type) relay, comprises a signal control source, capacitor charging and discharging circuit, function A circuit and an actuator, wherein the capacitor charging and discharging circuit can supply power to the actuator according to the current provided by the signal control source under the control of the functional circuit.

Among them, the signal control source is used to provide the current signal. The current signal can be DC or AC signal. If it is an AC signal, a diode is connected in series after the signal control source, and a DC current signal will be output accordingly. When there is a current signal output by the signal control source, the current charges the capacitor in the capacitor charging and discharging circuit, and the charging current can be used to supply power to the actuator (such as the coil of the relay), thereby controlling the action of the actuator.

The functional circuit is used to control the switch of the capacitor charging and discharging circuit. For example, in Figure 3A, the functional circuit is a pumping circuit, and in Figure 3B it is a voltage zero-crossing shutdown circuit. It is also possible to configure both functional circuits in Figure 3C. in the circuit. The capacitor charging and discharging circuit is used to perform corresponding charging and discharging when receiving the control signal of the functional circuit, and the capacitor is used as an energy storage element. When there is a current signal output by the signal control source, the current charges the capacitor, and the charging current is used to charge the The actuator (such as the coil of the relay) supplies power, and the capacitor is discharged through the discharge circuit composed of the actuator.

The capacitor charging and discharging circuit includes a capacitor, a diode, an NPN transistor, and a base bias resistor that supplies current to the base of the transistor. The positive pole of the actuator (such as a relay coil) is connected to the negative pole of the capacitor, and the negative pole of the actuator (such as a relay coil) is connected to the transistor. The emitter of the triode, the collector of the triode are connected to the positive pole of the capacitor, a base bias resistor is connected in series between the base and the capacitor, the anode of the diode is connected to the negative pole of the actuator, and the cathode of the diode is connected to the functional circuit. When the capacitor charging and discharging circuit receives the signal of the functional circuit, it forms a charging and discharging circuit with the actuator (such as a relay coil), and then the capacitor can be charged and discharged through the charging and discharging circuit, and a certain amplitude pulse signal is generated to drive the actuator, such as Make the relay pull in and out.

There can be multiple functional circuits, so as to realize different control functions, so that the capacitor charging and discharging circuit can be charged or discharged according to different controls.

The functional circuit can be a pumping circuit, as shown in Figure 3A, the pumping circuit controls the output of a voltage pulse signal with a certain amplitude according to the voltage signal of the signal control source, and outputs positive and negative pulses through the capacitor charging and discharging circuit correspondingly, so as to Control different actions of actuators, such as controlling the pull-in and disconnection of single-coil bistable (magnetic latching) relays.

Specifically, the pumping circuit may include a thyristor and a Zener diode. Among them, the cathode of the thyristor is connected to the ground wire, the control electrode of the thyristor is connected to the anode of the Zener diode, the cathode of the Zener diode is connected to the signal control source, and a current limiting device can also be connected between the Zener diode and the signal control source. Resistor, an anti-interference resistor is connected between the Zener diode and the cathode of the thyristor.

Utilizing the characteristic that the Zener diode will be broken down at a specific voltage, when the voltage of the signal control source is greater than the threshold of the Zener diode, the reverse breakdown will be turned on, and the pumping circuit will work to control the capacitor charge and discharge circuit to realize the capacitor charging and discharging circuit. charge and discharge.

According to this embodiment, the pumping circuit can be effectively used to ensure a certain amplitude of the voltage pulse signal, so that the principle of charging and discharging the capacitor can be used to generate the voltage pulse signal to drive the actuator.

In the circuit diagram shown in FIG. 4 , the switching on and off of the single-coil bistable (magnetic latching) relay is controlled by the capacitor charging and discharging circuit 30 .

The capacitor charging and discharging circuit 30 includes a capacitor C, an NPN transistor Q1, and a base bias resistor R3 that supplies current to the base of the transistor Q1, wherein the positive pole a of the coil of the relay 10 is connected to the negative pole of the capacitor C, and the negative pole b of the coil is connected to the emitter of the transistor Q1 , the collector of the transistor Q1 is connected to the positive pole of the capacitor C, and a base bias resistor R3 is connected in series between the base of Q1 and the capacitor C.

The functional circuit is a pumping circuit 20A, which may include a diode D2, a thyristor SCR1 and a Zener diode DZ1, wherein the anode of the diode D2 is connected to the negative pole b of the coil of the relay 10, and the cathode of the diode D2 is connected to the anode of the thyristor SCR1 , the cathode of the thyristor SCR1 is connected to the ground wire GND, the control pole of the thyristor SCR1 is connected to the anode of the Zener diode DZ1, and the cathode of the Zener diode DZ1 is connected to the signal control source DC signal. It can also be connected between the Zener diode DZ1 and the signal control A current-limiting resistor R1 is connected between the source DC signal, and an anti-interference resistor R2 is connected between the Zener diode DZ1 and the cathode of the thyristor SCR1.

When the input voltage signal DC signal is less than the threshold U _DZ of the Zener diode DZ1, the thyristor SCR1 does not trigger the conduction signal, and the SCR1 will not conduct, and accordingly the charging circuit cannot be formed in the circuit, and the bistable (magnetic holding type ) Relay 10 does not act.

When the input voltage signal DC signal is greater than the threshold U _DZ of the Zener diode DZ1, the thyristor SCR1 is turned on, and the current passes through the capacitor C, the coil of the relay 10, the diode D2 and the thyristor SCR1 to form a charging circuit. Due to the pulse during charging Voltage, a positive pulse of a certain width is added to the positive pole of the bistable (magnetic holding type) relay 10 to the negative pole, and the bistable (magnetic holding type) relay 10 will be closed. When the input voltage signal remains greater than U _DZ , the relay 10 will remain closed.

Afterwards, when the input voltage signal DC signal decreases, so that it is less than the threshold U _DZ of the Zener diode DZ1 or even disappears, the transistor Q1 will be turned on through the resistor R3. At this time, the capacitor C, the transistor Q1 and the bistable (magnetic holding type) The coil of the relay 10 forms a discharge circuit, the capacitor C is discharged, and a negative pulse of a certain width is added to the positive pole of the bistable (magnetic holding type) relay 10 to the negative pole, and the bistable (magnetic holding type) relay 10 is closed. becomes disconnected.

It can be seen that the embodiment of the present invention only uses a simple pumping circuit and a simple capacitor charging and discharging circuit to drive the actuator, especially to drive the single-coil bistable (magnetic latching) relay , the circuit is simple and convenient, and the cost is lower than using a single-chip microcomputer.

In addition, as shown in FIG. 3B, the functional circuit can also be a voltage zero-crossing shutdown circuit, including a photocoupler and a switch circuit. When there is no zero-crossing signal input at the input terminal of the photocoupler, the switch circuit will not be triggered to be turned on. Correspondingly, the switch circuit cannot form a discharge circuit with the actuator and the capacitor charging and discharging circuit, and the capacitor does not discharge; when the input terminal of the photocoupler has a zero-crossing signal input, the trigger switch circuit is turned on, and the switch circuit and the actuator and capacitor The charging and discharging circuit forms a discharging circuit, and the capacitor is discharged.

As shown in Figure 5, the functional circuit is used to control the capacitor charging and discharging circuit to turn off the bistable (magnetic latching) relay when the voltage crosses zero.

The switching circuit of the voltage zero-crossing shutdown circuit 20B includes two NPN transistors (Q23, Q22) and a thyristor SCR2, wherein the collector of Q23 is connected to the base of Q22, and the emitters of the two are connected together with the thyristor. The anode of SCR2 is connected, the collector of Q22 is connected to the control pole of the thyristor SCR2, and the cathode of the thyristor SCR2 is connected to the coil negative pole b of the bistable (magnetic latching) relay 10. A diode D22 is connected in antiparallel between the anode and cathode of the capacitor C, a bistable (magnetic latching) relay 10, a diode D3, and a thyristor SCR31 to form a charging circuit, and the current signal provided by the signal control source is used for charging. , using the principle that the thyristor is turned on when the anode potential is higher than the cathode potential, and the control pole has sufficient forward voltage and current, and the discharge circuit is composed of capacitor C, triode Q21, and bistable (magnetic latching) relay 10 , in order to turn off the relay when the voltage crosses zero. Of course, the thyristor SCR31 and the diode D22 connected in antiparallel can also be replaced by a reverse conducting thyristor (RCT).

A bias resistor R24 is connected in series between the collector of the transistor Q23 and the positive electrode of the capacitor to ensure the normal operation of the transistor Q23. The base of Q23 is also connected to the output terminal 16 of the optocoupler U1, and its emitter is connected to the anode of the thyristor SCR2. Connect a bias resistor R23 in series between the collector of Q22 and the positive electrode of the capacitor to ensure the normal operation of the transistor Q22. Connect the collector of Q23, preferably, an anti-interference resistor R22 can also be connected in parallel between the collector and the emitter.

The input terminal 1 of the photocoupler U1 can be connected to the live line 1 (L) of the bistable (magnetic latching) relay 10 through a current limiting resistor R26, and the other input terminal 2 is connected to the neutral line N. The input terminal of the optocoupler There are two anti-parallel diodes between 1 and input 2, so as to ensure that the triode of the photocoupler U1 is not turned on and has no output signal when there is a voltage zero-crossing signal regardless of the positive or negative half cycle. The output terminal 16 of the photocoupler U1 is the collector of the phototransistor, connected to the base of Q23, and a bias resistor R25 is connected in series between the positive electrodes of the capacitor to ensure its normal operation, and the other output terminal 15 is the collector of the phototransistor. The emitter is connected to the anode of the thyristor SCR2.

The capacitor charging and discharging circuit 30 includes a capacitor C, an NPN transistor Q21, and a base bias resistor R21 that supplies current to the base of the transistor Q21, wherein the positive pole a of the coil of the relay 10 is connected to the negative pole of the capacitor C, and the negative pole b of the coil is connected to the emitter of the transistor Q1 , the collector of the transistor Q1 is connected to the positive pole of the capacitor C, and a base bias resistor R3 is connected in series between the base of Q1 and the capacitor C.

In the circuit shown in Figure 5, when there is no zero-crossing signal input at the input terminal of the photocoupler U1, the receiving tube of the photocoupler U1 is turned on, the transistor Q23 is turned off, and the transistor Q22 is turned on, because the collector of Q22 is low level, the control pole of the thyristor SCR2 has no trigger signal cut-off, so the electric energy stored on the capacitor C cannot form a discharge circuit through the coil of the bistable (magnetic holding type) relay 10, and the bistable (magnetic holding type) The relay 10 does not act, and keeps the original state unchanged.

When the input terminal of the photocoupler U1 has a zero-crossing signal input, the receiving tube of the photocoupler U1 is cut off, the transistor Q23 is turned on, and the transistor Q22 is turned off. Since the collector is at a high level when the transistor Q22 is cut off, the thyristor SCR2 Therefore, the electric energy stored on the capacitor C can form a discharge circuit through the triode Q21, the thyristor SCR2 and the coil of the bistable (magnetic latching) relay 10, so as to realize the function of turning off the relay when it crosses zero. Purpose.

It can be seen that the embodiment of the present invention does not use a single-chip microcomputer to control, but only a simple electronic circuit is composed of a little hardware, and the control of the actuator when the voltage crosses zero can be realized more accurately. The contacts of the steady state (magnetic holding type) relay expand the rated load capacity of the bistable (magnetic holding type) relay, prolong the service life of the load, the circuit is relatively simple, and the cost is correspondingly relatively low.

In addition, as shown in FIG. 3C and FIG. 6, two functional circuits (pumping circuit 21 and voltage zero-crossing shutdown circuit 22) can also be connected together with the capacitor charging and discharging circuit 30 to form a circuit that can meet the requirements of driving such as An actuator such as a single-coil bistable (magnetic latching) relay, and turns off the circuit of the bistable (magnetic latching) relay when the voltage crosses zero.

The above descriptions are only illustrative specific implementations of the present invention, and are not intended to limit the scope of the present invention. Any equivalent changes, modifications and combinations made by those skilled in the art without departing from the concept and principle of the present invention shall fall within the protection scope of the present invention.

Claims (10)

1. A control circuit is characterized by comprising a signal control source, a capacitor charging and discharging loop, an executive element and a functional circuit connected with the capacitor charging and discharging loop, wherein the signal control source provides current for the capacitor charging and discharging loop, and the capacitor charging and discharging loop is used for supplying power to the executive element according to the control of the functional circuit.

2. The circuit of claim 1, wherein the capacitive charge-discharge circuit comprises a capacitor, a first diode, a first NPN transistor, and a base bias resistor for supplying current to the base of the transistor, wherein the positive terminal of the actuator is connected to the negative terminal of the capacitor, the negative terminal of the actuator is connected to the emitter of the transistor, the collector of the transistor is connected to the positive terminal of the capacitor, the base bias resistor is connected in series between the base of the transistor and the capacitor, the anode of the first diode is connected to the negative terminal of the actuator, and the cathode of the first diode is connected to the base of the transistor.

3. The circuit of claim 2, wherein the functional circuit is a pumping circuit comprising a first thyristor and a first zener diode, wherein a cathode of the first thyristor is connected to ground, a control electrode of the first thyristor is connected to an anode of the first zener diode, a cathode of the first zener diode is connected to the signal control source and an anode of the capacitor, and an anode of the first thyristor is connected to a cathode of the first diode.

4. The circuit of claim 3, wherein a current limiting resistor is connected in series between the first zener diode and the signal control source, and/or an interference rejection resistor is connected in series between the first zener diode and the cathode of the first thyristor.

5. The circuit of claim 2, wherein the functional circuit is a voltage zero crossing circuit, comprising a photocoupler and a switching circuit, and the switching circuit is not triggered to conduct when no zero crossing signal is input from the input terminal of the photocoupler; when zero-crossing signals are input at the input end of the photoelectric coupler, the switching circuit is triggered to be conducted, and the switching circuit, the capacitor charging and discharging loop and the execution element form a discharging loop.

6. The circuit of claim 5, wherein the switching circuit comprises a second NPN transistor (Q22), a third NPN transistor (Q23) and a second silicon controlled rectifier (SCR2), wherein a collector of the third NPN transistor (Q23) is connected to a base of the second NPN transistor (Q22), emitters of the third NPN transistor and the second NPN transistor are connected together to an anode of the second silicon controlled rectifier (SCR2), a collector of the second NPN transistor (Q22) is connected to a control electrode of the second silicon controlled rectifier (SCR2), and a cathode of the second silicon controlled rectifier (SCR2) is connected to a negative coil (b) of the relay.

7. The circuit of claim 6, wherein a second diode (D22) is connected in anti-parallel between the anode and cathode of the second silicon controlled rectifier (SCR 2).

8. The circuit of claim 6,

a resistor (R25) is connected in series between the collector of the optocoupler output triode and the positive electrode of the capacitor;

a resistor (R24) is connected between the base of the third NPN triode (Q23) and the positive electrode of the capacitor in series, the base of the third NPN triode (Q23) is also connected with the output end (16) of the photoelectric coupler (U1), the emitter of the third NPN triode (Q23) is connected with the anode of the second silicon controlled rectifier (SCR2), and the collector of the third NPN triode (Q23) is connected with the positive electrode of the capacitor through the resistor (R24);

the base electrode of the second NPN triode (Q22) is connected with the collector electrode of the third NPN triode (Q23), the emitter electrode of the second NPN triode (Q22) is connected with the anode of the second silicon controlled rectifier (SCR2), the collector electrode of the second NPN triode (Q22) is connected with the control electrode of the second silicon controlled rectifier (SCR2), and a resistor (R23) is connected between the collector electrode of the second NPN triode (Q22) and the positive electrode of the capacitor in series.

9. The circuit of claim 8,

a resistor (R22) is connected in parallel between the collector and the emitter of the second NPN transistor (Q22).

10. The circuit according to claim 6, characterized in that the input terminal (1) of the optocoupler (U1) is connected to the hot line of the actuator via a current limiting resistor (R26), the other input terminal (2) is connected to the neutral line, two diodes are connected in anti-parallel between the two input terminals, one output terminal (16) of the optocoupler (U1) is the collector of a phototransistor and is connected to the base of a third NPN transistor (Q23), and the other output terminal (15) is the emitter of the phototransistor and is connected to the anode of a second thyristor (SCR 2).

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