Bypass capacitor fault detection circuit and detection method
By using transistors with high amplification and low penetration current to form a composite circuit, combined with the pointer swing of the multimeter, the problem of being unable to quantitatively judge the degree of damage of the bypass capacitor in the prior art is solved, and more accurate capacitance detection is achieved.
Patent Information
- Application Number
- CN202411171297.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-26
- Publication Date
- 2025-02-07
AI Technical Summary
The prior art can only qualitatively check whether the bypass capacitor has leakage or short circuit through multimeter measurement, and it is impossible to quantitatively determine the degree of damage.
Two transistors with amplification ratio of β of AC current is 100 or more and a small penetration current are used to form a composite circuit. The amplification effect of the composite transistor and combined with the pointer swing of the multimeter, the degree of fault of the capacitor is accurately judged.
It can not only qualitatively check whether the capacitor has leakage or short circuit, but also quantitatively determine the degree of damage of the capacitor, improving the accuracy of detection.
Smart Images
Figure CN119395597A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of electronic component detection, and in particular relates to a bypass capacitor abnormality detection circuit and a detection method. Background Art
[0002] Capacitors are one of the most common electronic components and are also important components in electrical products. 10pF to 0.01uF capacitors are often used in power circuits to achieve bypass functions. Bypass capacitors are energy storage devices that provide energy to other devices in the circuit, which can make the output of the voltage regulator uniform and reduce load requirements. Bypass capacitors can be charged and can discharge to components.
[0003] At present, the test method for whether the bypass capacitor is abnormal is to use a multimeter to measure. When using a multimeter to measure, it can only qualitatively check whether the capacitor has leakage and whether the capacitor is short-circuited or broken down, but it cannot quantitatively determine the degree of damage to the bypass capacitor. Summary of the invention
[0004] The purpose of the present invention is to overcome the shortcomings of the prior art that only a multimeter can be used to measure whether a capacitor has leakage, but the degree of damage of the bypass capacitor cannot be quantitatively determined, and to provide a bypass capacitor abnormality detection circuit and detection method. The present invention uses two triodes with alternating current amplification factors β of more than 100 and small penetration current to form a composite circuit. By using the amplification effect of the composite triode, it can not only qualitatively check whether the capacitor has leakage, and whether there is a short circuit or breakdown inside, but also can further accurately determine the degree of capacitor failure according to the swing amplitude of the multimeter pointer.
[0005] To achieve the above purpose, the technical solution provided by the present invention is:
[0006] A bypass capacitor fault detection circuit is special in that it includes a transistor V1, a transistor V2, a multimeter and a capacitor to be tested;
[0007] One end of the capacitor under test is connected to the base of transistor V2;
[0008] The triode V1 and the triode V2 are connected in series to form a composite triode;
[0009] The other end of the capacitor under test is connected to the collector of the composite triode;
[0010] The multimeter is connected to the emitter and collector of the composite triode and is used to monitor the leakage resistance of the capacitor under test.
[0011] Furthermore, the alternating current amplification factors β of the transistor V1 and the transistor V2 are both greater than 100, and the penetration current is small.
[0012] Furthermore, the transistor V1 and the transistor V2 are NPN type high frequency low power silicon transistors.
[0013] Furthermore, the capacitance of the capacitor under test is 10pF to 0.01uF.
[0014] A bypass capacitor fault detection method comprises the following steps:
[0015] Step 1, releasing the residual charge in the bypass capacitor under test;
[0016] Step 2: construct a circuit according to the bypass capacitor fault detection circuit of claim 1;
[0017] Step 3. Connect the red and black test leads of the multimeter to the emitter and collector of transistor V2 respectively, and observe the swing of the multimeter pointer;
[0018] Then swap the test leads of the multimeter, connect the black test lead and the red test lead to the emitter and collector of transistor V2 respectively, and observe the swing of the multimeter pointer;
[0019] Step 4: Determine the abnormality of the fixed capacitor according to the swing of the multimeter pointer:
[0020] If the multimeter pointer returns to infinity after deflection in both tests and can no longer deflect, it indicates that the capacitor under test is normal;
[0021] If the multimeter pointer does not return to infinity after deflection at least once in the two tests, or deflects again after returning to infinity, it indicates that the capacitor under test is faulty:
[0022] (1) When the pointer first deflects clockwise to charge, and then slowly turns counterclockwise to return to the infinite position and does not return to the infinite position, the position indicated by the pointer after it stops is close to the infinite position, indicating that the capacitor has serious leakage and the leakage level is level one;
[0023] (2) When the pointer first deflects clockwise to charge, and then slowly turns counterclockwise to return to the infinite position but does not return to the infinite position, the position indicated by the pointer after it stops is far away from the infinite position, indicating that the capacitor leakage is more serious and the leakage level is level 2;
[0024] (3) If the multimeter pointer returns to the infinity position and then deflects clockwise again, it indicates that the capacitor leakage is very serious and the leakage level is level three.
[0025] Furthermore, the step 2 is specifically as follows:
[0026] Sub-step 2.1, connecting transistor V1 and transistor V2 in series to form a composite transistor;
[0027] Sub-step 2.2, connecting one end of the capacitor under test to the base of transistor V1;
[0028] Sub-step 2.3, connecting the other end of the capacitor under test to the collector of the composite triode.
[0029] The advantages of the present invention are:
[0030] The circuit of the present invention is simple in composition and is composed of two triodes with alternating current amplification factors β both being greater than 100 and with small penetration current and a multimeter. It is only necessary to connect the red test lead and the black test lead of the multimeter to the emitter and the collector of the composite tube respectively, and utilize the amplification effect of the composite triode to accurately judge the quality of the capacitor through the charging and discharging process of the capacitor.
[0031] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:
[0033] Figure 1 : Circuit connection diagram of the detection circuit of the present invention.
[0034] In the figure: Cx-fixed capacitor, RX1K-multimeter, V1-transistor, V2-transistor. DETAILED DESCRIPTION
[0035] Embodiments of the present invention are described in detail below. The embodiments are exemplary and intended to be used to explain the present invention, but should not be construed as limiting the present invention.
[0036] The present invention discloses a bypass capacitor abnormality detection circuit, comprising a transistor V1, a transistor V2 and a multimeter RX1K; one end of a fixed capacitor Cx is connected to the base of the transistor V1, the emitter of the transistor V1 is connected to the base of the transistor V2, the collector of the transistor V1 is connected to the collector of the transistor V2; the common end of the emitters of the transistors V1 and V2 is connected to the other end of the fixed capacitor Cx; the positive and negative electrodes of the multimeter are respectively connected to the emitter of the transistor V2 and the other end of the fixed capacitor Cx, and the multimeter is used to monitor the leakage resistance of the capacitor under test, and the monitoring range of the leakage resistance is 1-90 megohms.
[0037] The transistors V1 and V2 are transistors with AC current amplification factors β both greater than 100 and small penetration currents (between a few microamperes and a few milliamperes). In this embodiment, 3DG6 silicon transistors are used.
[0038] The method for using the detection circuit to perform fault detection on a bypass capacitor to be tested specifically comprises the following steps:
[0039] Step 1: Discharge the residual charge in the bypass capacitor to be tested;
[0040] Step 2: Build a circuit according to the bypass capacitor abnormality detection circuit above;
[0041] Step 3. Connect the red and black test leads of the multimeter to the emitter and collector of transistor V2 respectively, and observe the swing of the pointer on the multimeter; observe whether the multimeter needle can return to infinity after deflection;
[0042] Then swap the test leads of the multimeter, connect the black test lead and the red test lead to the emitter and collector of transistor V2 respectively, and observe whether the multimeter needle can return to infinity after deflection;
[0043] Step 4: Determine the abnormality of the fixed capacitor according to the swing of the multimeter pointer:
[0044] If the multimeter pointer returns to infinity after deflection in both tests and can no longer deflect, it indicates that the capacitor under test is normal;
[0045] If the multimeter pointer does not return to infinity after deflection at least once in the two tests, or deflects again after returning to infinity, it indicates that the capacitor under test is faulty:
[0046] (1) When the pointer first deflects clockwise to charge, and then slowly turns counterclockwise to return to the infinite position but does not return to the infinite position, the position indicated by the pointer after it stops is closer to the infinite position (with the middle position as a reference, the pointer is located on the side close to the infinite position), indicating that the capacitor has serious leakage and the leakage level is level one.
[0047] (2) When the pointer first deflects clockwise to charge, and then slowly turns counterclockwise to return to the infinite position and does not return to the infinite position, the position indicated by the pointer after it stops is far away from the infinite position (with the middle position as a reference, the pointer is on the side away from the infinite position), indicating that the capacitor leakage is more serious and the leakage level is level 2;
[0048] (3) If the multimeter pointer returns to the infinity position and then deflects clockwise again, it indicates that the capacitor leakage is very serious and the leakage level is level three.
[0049] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should be included in the protection scope of the present invention.
Claims
1. A bypass capacitor fault detection circuit, characterized in that: It includes transistor V1, transistor V2, multimeter and capacitor to be tested; One end of the capacitor under test is connected to the base of transistor V2; The triode V1 and the triode V2 are connected in series to form a composite triode; The other end of the capacitor under test is connected to the collector of the composite triode; The multimeter is connected to the emitter and collector of the composite triode and is used to monitor the leakage resistance of the capacitor under test.
2. The bypass capacitor fault detection circuit according to claim 1, characterized in that: The alternating current amplification factors β of the transistor V1 and the transistor V2 are both greater than 100, and the penetration current is small.
3. The bypass capacitor abnormality detection circuit according to claim 2, characterized in that: The transistor V1 and the transistor V2 are NPN type high frequency low power silicon transistors.
4. The bypass capacitor abnormality detection circuit according to claim 1, characterized in that: The capacitance of the capacitor to be measured is 10pF to 0.01uF.
5. A bypass capacitor fault detection method, characterized in that: The following steps are involved: Step 1, releasing the residual charge in the bypass capacitor under test; Step 2: construct a circuit according to the bypass capacitor fault detection circuit of claim 1; Step 3. Connect the red and black test leads of the multimeter to the emitter and collector of transistor V2 respectively, and observe the swing of the multimeter pointer; Then swap the test leads of the multimeter, connect the black test lead and the red test lead to the emitter and collector of transistor V2 respectively, and observe the swing of the multimeter pointer; Step 4: Determine the abnormality of the fixed capacitor according to the swing of the multimeter pointer: If the multimeter pointer returns to infinity after deflection in both tests and can no longer deflect, it indicates that the capacitor under test is normal; If the multimeter pointer does not return to infinity after deflection at least once in the two tests, or deflects again after returning to infinity, it indicates that the capacitor under test is faulty: (1) The pointer first deflects clockwise to charge, then slowly turns counterclockwise to return to the infinite position but does not return to the infinite position. After the pointer stops, the position indicated by it is close to the infinite position, indicating that the capacitor has serious leakage and the leakage level is level one; (2) The pointer first deflects clockwise to charge, then slowly turns counterclockwise to return to the infinite position but does not return to the infinite position. After the pointer stops, the position indicated by it is far away from the infinite position, indicating that the capacitor leakage is more serious and the leakage level is level 2. (3) If the multimeter pointer returns to the infinity position and then deflects clockwise again, it indicates that the capacitor leakage is very serious and the leakage level is level three.
6. The bypass capacitor fault detection method according to claim 4, characterized in that: The step 2 is specifically as follows: Sub-step 2.1, connecting transistor V1 and transistor V2 in series to form a composite transistor; Sub-step 2.2, connecting one end of the capacitor under test to the base of transistor V1; Sub-step 2.3, connecting the other end of the capacitor under test to the collector of the composite triode.