Multi-range automatic switching circuit

Abstract

The utility model relates to the technical field of circuits capable of automatically changing measuring ranges, in particular to a multi-measuring-range automatic switching circuit, which comprises measuring range control circuits with a plurality of measuring ranges, and is characterized in that each measuring range control circuit is used for carrying out current measurement in a corresponding measuring range so as to be displayed on an ampere meter; the current detection circuit is connected with each range control circuit and is used for detecting the current of each range control circuit; and the MCU main controller is respectively connected with the current detection circuit and each range control circuit and is used for comparing the current of each range control circuit with the corresponding set current and controlling whether each range control circuit is conducted or not according to the result. The situation that ampere meters with different measuring ranges are manually replaced can be reduced.

Description

Technical Field

[0001] The present application relates to the technical field of circuits for automatically changing ranges, and in particular to a multi-range automatic switching circuit. Background Art

[0002] Traditional 85C1 mechanical ammeters are widely used due to their fast response speed and high measurement accuracy. However, this type of ammeter usually has a single range problem. When it is necessary to test currents of different magnitudes, ammeters of different ranges must be replaced. This is not only inconvenient to operate, but also easy to introduce errors during frequent replacement. Utility Model Content

[0003] The purpose of the present application is to provide a multi-range automatic switching circuit, which can reduce the occurrence of manual replacement of ammeters with different ranges.

[0004] The present application provides a multi-range automatic switching circuit that adopts the following technical solution:

[0005] A multi-range automatic switching circuit, comprising:

[0006] Range control circuits of multiple ranges, each of which is used to measure current within a corresponding range for display on the ammeter;

[0007] A current detection circuit, connected to each of the range control circuits respectively, and used to detect the current of each of the range control circuits;

[0008] The MCU main controller is connected to the current detection circuit and each of the range control circuits respectively, and is used to compare the current of each of the range control circuits with the corresponding set current, and control whether each of the range control circuits is turned on or not according to the result.

[0009] By adopting the above technical solution, the current of each range control circuit is detected by the current detection circuit, and the MCU main controller is used to compare the various currents, so as to select the range control circuit suitable for the current to be turned on, thereby realizing automatic switching of the range.

[0010] Optionally, the first control circuit includes a main circuit and a control switch, the main circuit is electrically connected to the second control circuit, the control switch is used to control the on and off of the main circuit, and the MCU main controller is used to control the on and off of the control switch.

[0011] By adopting the above technical solution, the MCU main controller controls the closing of the control switch to achieve the control of the on-off of the first control circuit.

[0012] Optionally, the control switch includes a MOS tube and a switching power supply, the switching power supply is used to supply power to the gate of the MOS tube, and the MOS tube is electrically connected to the main circuit and is used to control the on and off of the main circuit.

[0013] By adopting the above technical solution, the on-off control of the main circuit is achieved through the cooperation of the MOS tube and the switching power supply. The MOS tube has good stability during use, making the connection of the entire main circuit more stable and reducing external interference.

[0014] Optionally, the switching power supply includes a first optocoupler and a first power supply, the MCU main controller is electrically connected to the first optocoupler and can control the on and off of the first optocoupler, the first power supply is electrically connected to the gate of the MOS tube, and the first optocoupler is used to control the on and off between the first power supply and the gate of the MOS tube.

[0015] By adopting the above technical solution, by setting the first optocoupler, the first optocoupler is electrically connected to the MCU main controller, so that the MCU main controller controls the on and off of the first optocoupler, thereby controlling the on and off of the MOS tube. Through the setting of the first optocoupler, electrical isolation is achieved, thereby reducing interference with the main circuit.

[0016] Optionally, a detection circuit is also included, which includes a connection terminal, a first resistor, a second resistor and a ground terminal electrically connected in sequence, and the MCU main controller is electrically connected between the first resistor and the second resistor and can receive a voltage signal at this position.

[0017] By adopting the above technical solution, the first resistor and the second resistor are connected in series to divide the voltage of the first resistor and the second resistor, and then the MCU main controller is used to receive the voltage signal at the position of the second resistor, so as to calculate the voltage flowing through the entire detection circuit at this time, and calculate the voltage value passing through the detection circuit.

[0018] Optionally, the detection circuit further includes a diode and a second power supply, wherein the cathode of the diode is electrically connected to the second power supply, and the anode of the diode is electrically connected between the first resistor and the second resistor.

[0019] By adopting the above technical solution, before the voltage flows into the MCU main controller, it will first flow toward the diode. If the voltage is too high, it will flow to the second power supply through the diode, thereby reducing the situation where excessive voltage flows into the MCU main controller and causes damage to the MCU main controller.

[0020] Optionally, the detection circuit also includes a third resistor and a fourth resistor, the third resistor is electrically connected to the second power supply, the fourth resistor is electrically connected to the third resistor and the ground terminal respectively, the connection terminal and the ground terminal are used to electrically connect the device to be detected, and the MCU main controller can be electrically connected between the third resistor and the fourth resistor and can receive the voltage signal at this position.

[0021] By adopting the above technical solution, the device to be tested is electrically connected to the wiring terminal and the ground terminal, powered by the second power supply, and then the MCU main controller is used to detect the voltage at the location of the fourth resistor, thereby calculating the voltage across the device to be tested, and determining whether the device to be tested is damaged.

[0022] In summary, the present application includes at least one of the following beneficial technical effects:

[0023] 1. Detect the current of each range control circuit through the current detection circuit, use the MCU main controller to compare the currents, so as to select the range control circuit suitable for the current to be turned on, and realize automatic switching of the range;

[0024] 2. Through the cooperation of MOS tube and switching power supply, the on-off control of the main circuit is realized. The MOS tube has good stability during use, making the connection of the entire main circuit more stable and reducing external interference;

[0025] 3. The device to be tested is electrically connected to the wiring terminal and the ground terminal, powered by the second power supply, and then the MCU main controller is used to detect the voltage at the location of the fourth resistor, thereby calculating the voltage across the device to be tested to determine whether the device to be tested is damaged. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a flow control diagram of a multi-range automatic switching circuit in an embodiment of the present application.

[0027] Figure 2 It is a circuit diagram of the first control circuit in the embodiment of the present application.

[0028] Figure 3 is a circuit diagram of a current detection circuit in an embodiment of the present application.

[0029] Figure 4 is a circuit diagram of the second control circuit in an embodiment of the present application.

[0030] Figure 5 is a circuit diagram of a detection circuit in an embodiment of the present application.

[0031] In the figure, 1. MCU main controller;

[0032] 2. Current detection circuit; 21. Detection unit;

[0033] 3. Range control circuit; 31. First control circuit; 311. Main circuit; 312. Control switch; 313. MOS tube; 314. Switching power supply; 3141. First optical coupler; 3142. First power supply; 32. Second control circuit;

[0034] 4. Detection circuit; 41. Wiring terminal; 42. First resistor; 43. Second resistor; 44. Ground terminal; 45. Diode; 46. Second power supply; 47. Third resistor; 48. Fourth resistor; 49. Second optocoupler. DETAILED DESCRIPTION

[0035] The following is combined with Figure 1 -Attached Figure 5 , further details of this application are given.

[0036] Embodiment 1:

[0037] A multi-range automatic switching circuit, referring to Figure 1 and Figure 2 , including a plurality of range control circuits 3, each range control circuit 3 is used to measure the current within a corresponding range to display it on the ammeter;

[0038] The current detection circuit 2 is connected to each range control circuit 3 respectively, and is used to detect the current of each range control circuit 3;

[0039] The MCU main controller 1 is connected to the current detection circuit 2 and each range control circuit 3, respectively, and is used to compare the current of each range control circuit 3 with the corresponding set current, and control whether each range control circuit 3 is turned on or off according to the result. In this embodiment, there are three range control circuits 3, and the three range control circuits 3 respectively control the three ranges on the ammeter; in other embodiments, the number of range control circuits 3 can be four, five or more, as long as it corresponds to the number of ranges on the ammeter.

[0040] The MCU main controller 1 includes multiple comparators corresponding to multiple range control circuits 3 one by one, and the two input ends of each comparator are used to receive the current of the corresponding range control circuit 3 and the corresponding set current respectively, and the output end of each comparator is used to control whether the corresponding range control circuit 3 is turned on.

[0041] Reference Figure 1 and Figure 3The current detection circuit 2 includes a plurality of detection units 21 corresponding to a plurality of range control circuits 3. The input end of each detection unit 21 is connected to the corresponding range control circuit 3, and the output end of each detection unit 21 is connected to the corresponding comparator. The MCU main controller 1 analyzes the current signal transmitted by the current detection circuit 2, so as to start the range control circuit 3 where the range most suitable for the current size is located, thereby realizing the switching of the range.

[0042] In this embodiment, in the initial stage, one of the range control circuits 3 is in a connection state, and the current detection circuit 2 is electrically connected to the range control circuit 3, so as to detect the current passed through the range control circuit 3. The current detection circuit 2 transmits the detected current signal to the MCU main controller 1. The MCU main controller 1 judges the current size and selects the appropriate range control circuit 3 to connect, so that the remaining range control circuits 3 are disconnected.

[0043] Reference Figure 1 and Figure 4 , each range control circuit 3 includes: a first control circuit 31, which is used to receive the signal to be measured when the range control circuit 3 is turned on, and use multiple resistors to adjust the current size of the signal to be measured; a second control circuit 32, which is used to output the signal to be measured after the current adjustment to the ammeter when the range control circuit 3 is turned on; wherein the resistance size in the first control circuit 31 of each of the range control circuits 3 is different. In this embodiment, the second control circuit 32 includes a relay, which is electrically connected to the MCU main controller 1, and the MCU main controller 1 can control the on and off of the relay. The relay is electrically connected to a range of the ammeter. When a second control circuit 32 is closed and operated, the relay electrically connected to it is closed, so that the ammeter range is operated. And the relay has good electrical isolation performance, which can effectively isolate the first control circuit 31 from the range of the ammeter. This helps to prevent electrical noise, interference or overvoltage from propagating to the ammeter range position.

[0044] Reference Figure 2 The first control circuit 31 includes a main circuit 311 and a control switch 312. The main circuit 311 is electrically connected to the second control circuit 32. When the main circuit 311 is connected, the second control circuit 32 is closed. The control switch 312 is used to control the on and off of the main circuit 311. The control switch 312 is electrically connected to the current detection circuit 2. When the current of the current detection circuit 2 is appropriate, the circuit control switch 312 of the current detection circuit 2 is closed, so that the main circuit 311 is closed, and the second control circuit 32 is closed.

[0045] In this embodiment, the control switch 312 includes a MOS tube 313 and a switching power supply 314. The MOS tube 313 is electrically connected to the main circuit 311. The switching power supply 314 is used to energize the gate of the MOS tube 313. When the switching power supply 314 energizes the gate of the MOS tube 313, the MOS tube 313 is closed, that is, the main circuit 311 is connected, thereby connecting the second control circuit 32.

[0046] In this embodiment, the switching power supply 314 includes a first power supply 3142 and a first optical coupler 3141. The first optical coupler 3141 has an a terminal, a b terminal, a c terminal and a d terminal. The a terminal and the b terminal are the two ends of the photosensitive diode in the first optical coupler 3141, and the c terminal and the d terminal are the two ends of the light-emitting diode in the first optical coupler 3141. The a terminal is electrically connected to the gate of the MOS tube 313, and the b terminal is electrically connected to the first power supply 3142. In this embodiment, the first power supply 3142 provides a -5V potential for the b terminal, the c terminal is electrically connected to the MCU main controller 1, and the MCU main controller 1 can provide current to the c terminal, and the d terminal is grounded.

[0047] The MCU main controller 1 controls whether to provide current to the c terminal to achieve connection and disconnection between the a terminal and the b terminal. When the a terminal is connected to the b terminal, the first power supply 3142 provides current to the MOS tube 313, thereby closing the MOS tube 313 and connecting the main circuit 311.

[0048] Reference Figure 5 A multi-range automatic switching circuit also includes a detection circuit 4, which includes a terminal 41, a first resistor 42, a second resistor 43 and a ground terminal 44. The terminal 41 is electrically connected to the first resistor 42, the first resistor 42 is electrically connected to the second resistor 43, the second resistor 43 is electrically connected to the ground terminal 44, and the MCU main controller 1 is electrically connected between the first resistor 42 and the second resistor 43 and can receive the voltage signal at this position. The voltage is input from the terminal 41, and the voltage is divided at the first resistor 42 and the second resistor 43. The MCU main controller 1 detects the voltage at the second resistor 43, and then calculates the voltage input to the terminal 41.

[0049] The detection circuit 4 also includes a diode 45 and a second power supply 46, the second power supply 46 is electrically connected to the cathode of the diode 45, and the anode of the diode 45 is electrically connected between the first resistor 42 and the second resistor 43, that is, the anode of the diode 45 is electrically connected to the first resistor 42 and the second resistor 43 at the same time. In this embodiment, the second power supply 46 provides a 3.3V voltage, and the second power supply 46 can be electrically connected to the MCU main controller 1 at the same time to power the MCU main controller 1.

[0050] Because the MCU main controller 1 cannot withstand a large voltage, when a large voltage is connected from the input end, in this embodiment, when the connected voltage is greater than 4V, the voltage will flow into the second power supply 46 through the diode 45, thereby reducing the 4V voltage directly flowing into the MCU main controller 1, causing damage to the main controller.

[0051] The detection circuit 4 also includes a third resistor 47, a fourth resistor 48 and a second optical coupler 49. The second optical coupler 49 has an A end, a B end, a C end and a D end. The A end and the B end are the two ends of the photosensitive diode in the second optical coupler 49, and the C end and the D end are the two ends of the light-emitting diode in the second optical coupler 49. The A end is electrically connected to the second power supply 46, the B end is electrically connected to the input end, and the C end is electrically connected to the power supply. The second power supply 46, the third resistor 47, the fourth resistor 48 and the ground terminal 44 are electrically connected in sequence. The MCU main controller 1 is electrically connected between the third resistor 47 and the fourth resistor 48, that is, the MCU main controller 1 is electrically connected to the third resistor 47 and the fourth resistor 48 respectively, and the MCU main controller 1 can measure the voltage at the location of the fourth resistor 48 at this time.

[0052] When it is necessary to test the device under test, such as a diode, the two ends of the diode need to be electrically connected to the input end and the ground terminal 44. When the second optocoupler 49 is closed, a low level is supplied to the D end, so that the A end is connected to the B end. At this time, the voltage at the location of the fourth resistor 48 is detected and converted to obtain the voltage at both ends of the diode. Whether the diode is damaged is determined by the voltage reading.

[0053] The implementation principle of the embodiment of the present application is: the input current is detected by the current detection circuit 2, and the current signal is input into the MCU main controller 1, the MCU main controller 1 determines the current size and selects a suitable main circuit 311, connects the first optocoupler 3141 electrically connected to the main circuit 311, closes the MOS tube 313 on the main circuit 311, and then connects the main circuit 311, and at the same time controls a suitable second control circuit 32 to close, so as to achieve the switching of the range.

[0054] The embodiments of this specific implementation are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. The same components are represented by the same figure marks. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A multi-range automatic switching circuit, characterized in that: include: A range control circuit (3) having a plurality of ranges, each of the range control circuits (3) being used to measure current within a corresponding range so as to display the current on an ammeter; A current detection circuit (2) connected to each of the range control circuits (3) respectively, and used to detect the current of each of the range control circuits (3); The MCU main controller (1) is connected to the current detection circuit (2) and each of the range control circuits (3) respectively, and is used to compare the current of each of the range control circuits (3) with the corresponding set current, and control whether each of the range control circuits (3) is turned on or off according to the result.

2. The multi-range automatic switching circuit according to claim 1, characterized in that: The MCU main controller (1) comprises a plurality of comparators corresponding one to one with the plurality of range control circuits (3), the two input ends of each of the comparators being used to respectively receive the current of the corresponding range control circuit (3) and the corresponding set current, and the output end of each of the comparators being used to control whether the corresponding range control circuit (3) is turned on.

3. The multi-range automatic switching circuit according to claim 2, characterized in that: The current detection circuit (2) comprises a plurality of detection units (21) corresponding one-to-one to the plurality of range control circuits (3), the input end of each detection unit (21) being connected to the corresponding range control circuit (3), and the output end of each detection unit (21) being connected to the corresponding comparator.

4. The multi-range automatic switching circuit according to claim 1, characterized in that: Each of the range control circuits (3) comprises: A first control circuit (31) is used to receive a signal to be measured when the range control circuit (3) is turned on, and to adjust the current of the signal to be measured using a plurality of resistors; A second control circuit (32) is used to output a current-adjusted signal to be measured to an ammeter when the range control circuit (3) is turned on; The resistance in the first control circuit (31) of each of the range control circuits (3) is different in size.

5. The multi-range automatic switching circuit according to claim 4, characterized in that: The first control circuit (31) comprises a main circuit (311) and a control switch (312); the main circuit (311) is electrically connected to the second control circuit (32); the control switch (312) is used to control the on and off of the main circuit (311); and the MCU main controller (1) is used to control the on and off of the control switch (312).

6. A multi-range automatic switching circuit according to claim 5, characterized in that: The control switch (312) comprises a MOS tube (313) and a switch power supply (314); the switch power supply (314) is used to supply power to the gate of the MOS tube (313); the MOS tube (313) is electrically connected to the main circuit (311) and is used to control the on and off of the main circuit (311).

7. A multi-range automatic switching circuit according to claim 6, characterized in that: The switching power supply (314) comprises a first optical coupler (3141) and a first power supply (3142); the MCU main controller (1) is electrically connected to the first optical coupler (3141) and is capable of controlling the on / off of the first optical coupler (3141); the first power supply (3142) is electrically connected to the gate of the MOS tube (313); and the first optical coupler (3141) is used to control the on / off between the first power supply (3142) and the gate of the MOS tube (313).

8. The multi-range automatic switching circuit according to claim 1, characterized in that: The invention also comprises a detection circuit (4), wherein the detection circuit (4) comprises a connection terminal (41), a first resistor (42), a second resistor (43) and a ground terminal (44) which are electrically connected in sequence, and the MCU main controller (1) is electrically connected between the first resistor (42) and the second resistor (43).

9. A multi-range automatic switching circuit according to claim 8, characterized in that: The detection circuit (4) further comprises a diode (45) and a second power supply (46); the cathode of the diode (45) is electrically connected to the second power supply (46); and the anode of the diode (45) is electrically connected between the first resistor (42) and the second resistor (43).

10. A multi-range automatic switching circuit according to claim 9, characterized in that: The detection circuit (4) further comprises a third resistor (47) and a fourth resistor (48), wherein the third resistor (47) is electrically connected to the second power supply (46), and the fourth resistor (48) is electrically connected to the third resistor (47) and the ground terminal (44) respectively; the connection terminal (41) and the ground terminal (44) are used to electrically connect the device to be detected; and the MCU main controller (1) can be electrically connected between the third resistor (47) and the fourth resistor (48) and can receive a voltage signal at this position.

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