A signal conversion circuit, a magnetic latching device and an energy storage power supply

Abstract

The utility model relates to the technical field of energy storage power supply especially relates to a signal conversion circuit, magnetic retaining device and energy storage power supply, the signal conversion circuit includes first conversion module and second conversion module, first conversion module with second conversion module all are connected with signal source, first conversion module and second conversion module all are used for receiving the control signal that signal source output, and when the control signal is switched from first control signal to second control signal, first conversion module exports first pulse signal, when the control signal is switched from second control signal to first control signal, second conversion module will export second pulse signal. Based on this, when the signal conversion circuit is used to control magnetic retaining relay, the working state of switching magnetic retaining relay can be realized through an IO, and resources are saved further.

Description

Technical Field

[0001] This utility model relates to the technical field of energy storage power supply, and in particular to a signal conversion circuit, a magnetic holding device, and an energy storage power supply. Background Technology

[0002] In the field of power electronics, with the trend towards intelligent and integrated development, microcontrollers (MCUs), as core control units, are widely used in various power conversion and control scenarios. In controlling devices such as magnetic latching relays, traditional methods typically require multiple I / O ports of the MCU to output different control signals to achieve different operating states of the device. Magnetic latching relays, with their advantages of low power consumption and high reliability, are widely used in smart meters, new energy vehicle battery management systems, and energy storage power stations. However, their bistable characteristics (normally open / normally closed state switching) require the MCU to output positive and negative pulse signals through at least two independent I / O ports to control the on / off state of the relay's internal electromagnetic coil, thereby achieving state switching. Simultaneously, additional I / O ports are needed to monitor the relay's state to ensure control accuracy. This control method results in a significant occupation of the MCU's I / O port resources, leading to resource waste. Therefore, to improve resource utilization, it is necessary to propose a signal conversion circuit. Utility Model Content

[0003] This utility model provides a signal conversion circuit, a magnetic latching device, and an energy storage power supply, aiming to solve the technical problem of low resource utilization rate of magnetic latching relays in the prior art.

[0004] To solve the above-mentioned technical problems, one technical solution adopted by this utility model is to provide a signal conversion circuit, including a first conversion module and a second conversion module;

[0005] Both the first conversion module and the second conversion module are connected to the signal source;

[0006] The first conversion module is used to receive the control signal output by the signal source, and output a first pulse signal when the control signal is switched from a first control signal to a second control signal; and

[0007] The output signal is stopped when the control signal is the first control signal;

[0008] The second conversion module is used to receive the control signal output by the signal source, and output a second pulse signal when the control signal is switched from a second control signal to a first control signal; and

[0009] The output signal is stopped when the control signal is the second control signal.

[0010] Optionally, the first control signal is a low-level signal, and the second control signal is a high-level signal.

[0011] Optionally, the first conversion module includes a first delay unit and a first conversion unit;

[0012] The first delay unit is connected to the first conversion unit, and both the first delay unit and the first conversion unit are also used to connect to the signal source;

[0013] The first conversion unit is used to output the first pulse signal in response to the charging process of the first delay unit when the control signal is switched from the first control signal to the second control signal.

[0014] Optionally, the first delay unit includes a capacitor C1 and a resistor R2;

[0015] The first terminal of capacitor C1 is connected to the signal source through resistor R2. The first terminal of capacitor C1 is also connected to the first conversion unit. The second terminal of capacitor C1 is used for grounding.

[0016] Optionally, the first conversion unit includes a NOT gate U2 and an AND gate U1;

[0017] The input terminal of the NOT gate U2 is connected to the first delay unit, the output terminal of the NOT gate U2 is connected to the second input terminal of the AND gate U1, and the first input terminal of the AND gate U1 is connected to the signal source.

[0018] Optionally, the second conversion module includes a second delay unit and a second conversion unit;

[0019] The second delay unit is connected to the second conversion unit, and both the second delay unit and the second conversion unit are also used to connect to the signal source;

[0020] The second conversion unit is used to output the second pulse signal in response to the discharge process of the second delay unit when the control signal is switched from the second control signal to the first control signal.

[0021] Optionally, the second conversion unit includes NOT gate U3 and NOR gate U4;

[0022] The input terminal of the NOT gate U3 is connected to the second delay unit, the output terminal of the NOT gate U3 is connected to the second input terminal of the NOR gate U4, and the first input terminal of the NOR gate U4 is connected to the signal source.

[0023] To solve the above-mentioned technical problems, another technical solution adopted by the present invention is: to provide a magnetic holding device, the magnetic holding device including a magnetic holding relay, a first driving circuit, a second driving circuit and the signal conversion circuit as described above;

[0024] Both the first driving circuit and the second driving circuit are connected to the signal conversion circuit, and both the first driving circuit and the second driving circuit are also connected to the magnetic latching relay;

[0025] The first driving circuit is used to receive the first pulse signal output by the signal conversion circuit, and output a first driving signal to the magnetic latching relay according to the first pulse signal, so as to control the magnetic latching relay to switch from the first state to the second state;

[0026] The second driving circuit is used to receive the second pulse signal output by the signal conversion circuit, and output a second driving signal to the magnetic latching relay according to the second pulse signal, so as to control the magnetic latching relay to switch from the second state to the first state.

[0027] Optionally, the first driving circuit includes a switching transistor Q1, a resistor R1, and a resistor R3;

[0028] The control terminal of the switch Q1 is connected to the first conversion module through the resistor R1. The control terminal of the switch Q1 is also grounded through the resistor R3. The first terminal of the switch Q1 is connected to the magnetic latching relay, and the second terminal of the switch Q1 is grounded.

[0029] To solve the above-mentioned technical problems, another technical solution adopted in this utility model embodiment is to provide an energy storage power supply, wherein the energy storage power supply includes the magnetic holding device described above.

[0030] Unlike related technologies, this utility model provides a signal conversion circuit, a magnetic latching device, and an energy storage power supply. The signal conversion circuit includes a first conversion module and a second conversion module, both connected to a signal source. Both the first and second conversion modules receive control signals output from the signal source. When the control signal switches from a first control signal to a second control signal, the first conversion module outputs a first pulse signal; when the control signal switches from a second control signal to a first control signal, the second conversion module outputs a second pulse signal. Therefore, when the signal conversion circuit is used to control a magnetic latching relay, the operating state of the magnetic latching relay can be switched using a single I / O operation, thus saving resources. Attached Figure Description

[0031] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0032] Figure 1 This is a structural block diagram of an energy storage power supply provided in an embodiment of this utility model;

[0033] Figure 2 This is a structural block diagram of a signal conversion circuit provided in an embodiment of the present invention;

[0034] Figure 3 This is a circuit diagram of a signal conversion circuit provided in an embodiment of the present invention. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.

[0036] The technical features involved in the various embodiments of this application described below do not conflict with each other and can be combined with each other.

[0037] When an element is described as "connected" to another element, it can be directly connected to the other element, or there may be one or more intervening elements between them.

[0038] The terms "first," "second," etc., used in the specification and claims of this utility model are used to distinguish similar objects and are not used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, the first object can be one or more.

[0039] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0040] Please see Figure 1 , Figure 1 This is a structural block diagram of an energy storage power supply provided in an embodiment of this utility model, as shown below. Figure 1 As shown, the energy storage power supply 1 includes a signal source 100 and a magnetic holding device 200; the signal source 100 is connected to the magnetic holding device 200. The signal source 100 is used to output control signals to the magnetic holding device 200 to control the working state of the magnetic holding device 200.

[0041] In another embodiment, such as Figure 1 As shown, the magnetic latching device 200 includes a first driving circuit 10, a second driving circuit 20, a signal conversion circuit 30, and a magnetic latching relay 40;

[0042] The first driving circuit 10 and the second driving circuit 20 are both connected to the signal conversion circuit 30, and the first driving circuit 10 and the second driving circuit 20 are also both connected to the magnetic latching relay 40.

[0043] The first driving circuit 10 is used to receive the first pulse signal output by the signal conversion circuit 30, and output a first driving signal to the magnetic latching relay 40 according to the first pulse signal, so as to control the magnetic latching relay 40 to switch from the first state to the second state;

[0044] The second driving circuit 20 is used to receive the second pulse signal output by the signal conversion circuit 30, and output a second driving signal to the magnetic latching relay 40 according to the second pulse signal, so as to control the magnetic latching relay 40 to switch from the second state to the first state.

[0045] In some embodiments, the signal conversion circuit 30 is connected to the signal source 100. When the signal source 100 outputs a control signal, the signal conversion circuit 30 processes the control signal to output a first pulse signal or a second pulse signal. When the signal conversion circuit 30 outputs the first pulse signal, the first drive circuit 10 receives the first pulse signal and outputs a first drive signal to the magnetic latching relay 40 according to the first pulse signal to control the magnetic latching relay 40 to switch from a first state to a second state. When the signal conversion circuit 30 outputs the second pulse signal, the second drive circuit 20 controls the magnetic latching relay 40 to switch from the second state to the first state according to the second pulse signal. It should be noted that the magnetic latching relay 40 includes two states: off and closed. When the first state is closed, the second state is off; and if the first state is off, the second state is closed.

[0046] In other embodiments, please refer to Figure 2 , Figure 2 This is a structural block diagram of a signal conversion circuit provided in an embodiment of the present invention, as shown below. Figure 2 As shown, the signal conversion circuit 30 includes a first conversion module 31 and a second conversion module 32;

[0047] Both the first conversion module 31 and the second conversion module 32 are connected to the signal source 100;

[0048] The first conversion module 31 is used to receive the control signal output by the signal source 100, and output a first pulse signal when the control signal is switched from the first control signal to the second control signal; and

[0049] The output signal is stopped when the control signal is the first control signal;

[0050] The second conversion module 32 is used to receive the control signal output by the signal source 100, and output a second pulse signal when the control signal is switched from a second control signal to a first control signal; and

[0051] The output signal is stopped when the control signal is the second control signal.

[0052] Specifically, when the signal source 100 starts outputting a control signal, both the first conversion module 31 and the second conversion unit 32 will receive the control signal. At this time, if the control signal is switched from the first control signal to the second control signal, the first conversion module 31 will output a first pulse signal, and the second conversion module 32 will stop outputting signals based on the second control signal.

[0053] If the control signal is switched from the second control signal to the first control signal, the second conversion unit 32 will output a second pulse signal, and the first conversion module 31 will stop outputting signals according to the first control signal.

[0054] In some embodiments, the first control signal is a low-level signal, and the second control signal is a high-level signal. It is understood that when the signal source 100 does not output a control signal, the control signals received by the first conversion module 31 and the second conversion module 32 are low-level signals, meaning that the first conversion module 31 and the second conversion module 32 are implicitly receiving the first control signal. At this time, if the signal source 100 starts outputting a high-level signal, the control signal received by the first conversion module 31 will be converted from the first control signal to the second control signal, and the first conversion module 31 will start outputting a first pulse signal, while the second conversion module 32 will stop outputting signals. When the signal source 100 stops outputting signals again or outputs the first control signal, the first conversion module 31 will stop working according to the first control signal, and the control signal received by the second conversion module 32 will switch from the second control signal to the first control signal, and the second conversion module 32 will output a second pulse signal. Based on this, even with only a single input source, two different signals can be output according to the signal state of the input source, thereby saving resources.

[0055] In some embodiments, such as Figure 2 As shown, the first conversion module 31 is connected to the first drive circuit 10, and the second conversion module 32 is connected to the second drive circuit 20. When the first conversion module 31 outputs the first pulse signal, the first drive circuit 10 receives the first pulse signal and controls the magnetic latching relay 40 to switch from a first state to a second state according to the first pulse signal; while when the second drive circuit 20 receives the second pulse signal output by the second conversion module 32, it controls the magnetic latching relay 40 to switch from the second state to the first state according to the second pulse signal. Based on this, the operating state of the magnetic latching relay 40 can be controlled by the signal conversion circuit 30.

[0056] In yet another embodiment, such as Figure 2 As shown, the first conversion module 31 includes a first delay unit 311 and a first conversion unit 312;

[0057] The first delay unit 311 is connected to the first conversion unit 312, and both the first delay unit 311 and the first conversion unit 312 are also used to connect to the signal source 100;

[0058] The first conversion unit 312 is used to output the first pulse signal in response to the charging process of the first delay unit 311 when the control signal is switched from the first control signal to the second control signal.

[0059] When the control signal output by the signal source 100 is the first control signal, the first conversion unit 312 will directly output a low-level signal according to the first control signal. When the control signal switches from the first control signal to the second control signal, the first delay unit 311 will receive the second control signal and start charging based on the second control signal. At the same time, the first conversion unit 312 will also receive the second control signal and determine whether it receives the voltage signal output by the first delay unit 311. If it does not receive the voltage signal, the first conversion unit 311 will switch to output a high-level signal. It should be noted that during the charging process of the first delay unit 311, the second control signal will be directly input to the first delay unit 311, so the first delay unit 311 will not output a voltage signal.

[0060] When the first delay unit 311 finishes charging, it outputs a voltage signal to the first conversion unit 312 based on the second control signal. Upon receiving the voltage signal, the first conversion unit 312 switches to output a low-level signal. Therefore, the first conversion module 32 can output a first pulse signal when the control signal switches from the first control signal to the second control signal.

[0061] In some embodiments, please refer to Figure 3 , Figure 3 This is a circuit diagram of a signal conversion circuit provided in an embodiment of this utility model, such as... Figure 3 As shown, the first delay unit 311 includes a capacitor C1 and a resistor R2; the first conversion unit 312 includes a NOT gate U2 and an AND gate U1;

[0062] The first terminal of capacitor C1 is connected to the signal source 100 through resistor R2. The first terminal of capacitor C1 is also connected to the first conversion unit 312. The second terminal of capacitor C1 is used for grounding.

[0063] The input terminal of the NOT gate U2 is connected to the first delay unit 311, the output terminal of the NOT gate U2 is connected to the second input terminal of the AND gate U1, and the first input terminal of the AND gate U1 is connected to the signal source 100.

[0064] When the control signal output by the signal source 100 is the first control signal, the first control signal will be directly input to the input terminal of the AND gate U1. At this time, the AND gate U1 will directly output a low-level signal.

[0065] When the control signal output by the signal source 100 switches from the first control signal to the second control signal, the second control signal is input to the capacitor C1 through the resistor R2 to charge the capacitor C1. Simultaneously, the first input terminal of the AND gate U1 also receives the second control signal. During the charging process of the capacitor C1, the NOT gate U2 does not receive a voltage signal (i.e., it receives a low-level signal), so the NOT gate U2 outputs a high-level signal to the second input terminal of the AND gate U1. When both the first and second input terminals of the AND gate U1 receive high-level signals, the AND gate U1 switches to output a high-level signal.

[0066] When capacitor C1 finishes charging, NOT gate U2 receives a voltage signal (i.e., a high-level signal). At this time, NOT gate U2 outputs a low-level signal to the second input of AND gate U1 based on this high-level signal. When AND gate U1 receives the low-level signal, it immediately switches to outputting a low-level signal. Based on this, the second conversion unit 312 can output a first pulse signal according to the charging process of capacitor C1.

[0067] In yet another embodiment, such as Figure 2 As shown, the second conversion module 32 includes a second delay unit 321 and a second conversion unit 322;

[0068] The second delay unit 321 is connected to the second conversion unit 322, and both the second delay unit 321 and the second conversion unit 322 are also used to connect to the signal source 100;

[0069] The second conversion unit 322 is used to output the second pulse signal in response to the discharge process of the second delay unit 321 when the control signal is switched from the second control signal to the first control signal.

[0070] When the control signal output by the signal source 100 is the first control signal, the second conversion unit 322 will output a low-level signal according to the first control signal. When the control signal is switched from the first control signal to the second control signal, the second delay unit 321 will charge based on the second control signal, and at the same time, the second conversion unit 322 will also receive the second control signal, and will continue to output a low-level signal when it does not receive the discharge signal output by the second delay unit 321.

[0071] When the control signal switches from the second control signal to the first control signal, the second delay unit 321 begins to discharge to the second conversion unit 322. Simultaneously, the second conversion unit 322 also receives the first control signal. When the second conversion unit 322 receives both the first control signal and the discharge signal, it switches to a high-level signal output. After the second delay unit 321 finishes discharging, the second conversion unit 322 no longer receives the discharge signal and outputs a low-level signal again. Based on this, the second conversion unit 322 can output a second pulse signal based on the discharge process of the second delay unit 321.

[0072] In other embodiments, such as Figure 3 As shown, the second delay unit 321 includes a capacitor C2 and a resistor R5; the second conversion unit 322 includes a NOT gate U3 and a NOR gate U4;

[0073] The first terminal of capacitor C2 is connected to the signal source 100 through resistor R5. The first terminal of capacitor C2 is also connected to the second conversion unit 322. The second terminal of capacitor C2 is used for grounding.

[0074] The input terminal of the NOT gate U3 is connected to the second delay unit 321, the output terminal of the NOT gate U3 is connected to the second input terminal of the NOR gate U4, and the first input terminal of the NOR gate U4 is connected to the signal source 100.

[0075] When the control signal is the first control signal, the NOR gate U4 outputs a low-level signal. When the control signal switches from the first control signal to the second control signal, the capacitor C2 charges through the resistor R5. At this time, the NOT gate U3 outputs a high-level signal to the second input terminal of the NOR gate U4, and the first input terminal of the NOR gate U4 receives the second control signal and continuously outputs a low-level signal according to the control signal. When the control signal switches from the second control signal to the first control signal, the capacitor C2 begins to discharge through the NOT gate U3 to the second input terminal of the NOR gate U4. At this time, both input terminals of the NOR gate U4 receive a low-level signal, thus outputting a high-level signal. After the capacitor C2 finishes discharging, the second input terminal of the NOR gate U4 receives a high-level signal again, and the NOR gate U4 switches back to outputting a low-level signal. Based on this, the NOR gate U4 can output a second pulse signal based on the charging and discharging of the capacitor C2.

[0076] In some embodiments, such as Figure 3 As shown, the first driving circuit 10 includes a switching transistor Q1, a resistor R1, and a resistor R3;

[0077] The control terminal of the switch Q1 is connected to the first conversion module 31 through the resistor R1. The control terminal of the switch Q1 is also grounded through the resistor R3. The first terminal of the switch Q1 is connected to the magnetic latching relay 40, and the second terminal of the switch Q1 is grounded.

[0078] When the first conversion module 31 outputs the first pulse signal, the switching transistor Q1 receives the first pulse signal through the resistor R1 and starts working according to the first pulse signal, thereby outputting a first drive signal to the magnetic latching relay 40 to control the magnetic latching relay 40 to switch its working state.

[0079] In other embodiments, such as Figure 3 As shown, the second driving circuit 20 includes a switching transistor Q2, a resistor R4, and a resistor R7;

[0080] The control terminal of the switching transistor Q2 is connected to the second conversion module 32 through the resistor R4, and the control terminal of the switching transistor Q2 is also grounded through the resistor R7. The first terminal of the switching transistor Q2 is connected to the magnetic latching relay 40, and the second terminal of the switching transistor Q2 is grounded. It should be noted that the second driving circuit 20 works on the same principle as the first driving circuit 10, and will not be described again here.

[0081] This application provides a signal conversion circuit, which includes a first conversion module and a second conversion module. Both the first and second conversion modules are connected to a signal source. Both the first and second conversion modules receive control signals output from the signal source. When the control signal switches from a first control signal to a second control signal, the first conversion module outputs a first pulse signal; when the control signal switches from a second control signal to a first control signal, the second conversion module outputs a second pulse signal. Therefore, when the signal conversion circuit is used to control a magnetic latching relay, the operating state of the magnetic latching relay can be switched using a single I / O operation, thereby saving resources.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it; under the concept of this utility model, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of this utility model as described above, which are not provided in detail for the sake of brevity; although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A signal conversion circuit, characterized in that, Includes a first conversion module and a second conversion module; Both the first conversion module and the second conversion module are connected to the signal source; The first conversion module is used to receive the control signal output by the signal source, and output a first pulse signal when the control signal is switched from the first control signal to the second control signal; as well as The output signal is stopped when the control signal is the first control signal; The second conversion module is used to receive the control signal output by the signal source, and output a second pulse signal when the control signal is switched from the second control signal to the first control signal; as well as The output signal is stopped when the control signal is the second control signal.

2. The signal conversion circuit according to claim 1, characterized in that, The first control signal is a low-level signal, and the second control signal is a high-level signal.

3. The signal conversion circuit according to claim 1 or 2, characterized in that, The first conversion module includes a first delay unit and a first conversion unit; The first delay unit is connected to the first conversion unit, and both the first delay unit and the first conversion unit are also used to connect to the signal source; The first conversion unit is used to output the first pulse signal in response to the charging process of the first delay unit when the control signal is switched from the first control signal to the second control signal.

4. The signal conversion circuit according to claim 3, characterized in that, The first delay unit includes a capacitor C1 and a resistor R2; The first terminal of capacitor C1 is connected to the signal source through resistor R2. The first terminal of capacitor C1 is also connected to the first conversion unit. The second terminal of capacitor C1 is used for grounding.

5. The signal conversion circuit according to claim 3, characterized in that, The first conversion unit includes a NOT gate U2 and an AND gate U1; The input terminal of the NOT gate U2 is connected to the first delay unit, the output terminal of the NOT gate U2 is connected to the second input terminal of the AND gate U1, and the first input terminal of the AND gate U1 is connected to the signal source.

6. The signal conversion circuit according to claim 1 or 2, characterized in that, The second conversion module includes a second delay unit and a second conversion unit; The second delay unit is connected to the second conversion unit, and both the second delay unit and the second conversion unit are also used to connect to the signal source; The second conversion unit is used to output the second pulse signal in response to the discharge process of the second delay unit when the control signal is switched from the second control signal to the first control signal.

7. The signal conversion circuit according to claim 6, characterized in that, The second conversion unit includes NOT gate U3 and NOR gate U4; The input terminal of the NOT gate U3 is connected to the second delay unit, the output terminal of the NOT gate U3 is connected to the second input terminal of the NOR gate U4, and the first input terminal of the NOR gate U4 is connected to the signal source.

8. A magnetic holding device, characterized in that, The magnetic latching device includes a magnetic latching relay, a first driving circuit, a second driving circuit, and a signal conversion circuit as described in any one of claims 1-7; Both the first driving circuit and the second driving circuit are connected to the signal conversion circuit, and both the first driving circuit and the second driving circuit are also connected to the magnetic latching relay; The first driving circuit is used to receive the first pulse signal output by the signal conversion circuit, and output a first driving signal to the magnetic latching relay according to the first pulse signal, so as to control the magnetic latching relay to switch from the first state to the second state; The second driving circuit is used to receive the second pulse signal output by the signal conversion circuit, and output a second driving signal to the magnetic latching relay according to the second pulse signal, so as to control the magnetic latching relay to switch from the second state to the first state.

9. The magnetic holding device according to claim 8, characterized in that, The first driving circuit includes a switching transistor Q1, a resistor R1, and a resistor R3; The control terminal of the switch Q1 is connected to the first conversion module through the resistor R1. The control terminal of the switch Q1 is also grounded through the resistor R3. The first terminal of the switch Q1 is connected to the magnetic latching relay, and the second terminal of the switch Q1 is grounded.

10. An energy storage power source, characterized in that, The energy storage power source includes the magnetic holding device as described in claim 8 or 9.

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