CN111404124A - A protection circuit for reverse connection of polar electrolytic capacitors by using NOT gate or AND gate - Google Patents

Abstract

In the present invention, a non-gate is used to realize the protection circuit for reverse connection of electrolytic capacitors with polarities. The DC power supply circuit is composed; the protection circuit of the reverse connection of the polar electrolytic capacitor is realized by the AND gate of the present invention, and the polar electrolytic capacitor E1, the capacitor terminal JP2, the AND gate U2A, the AND gate U2B, the transistor Q2, the relay JDQ2, The light-emitting diode LED2 and the DC power supply circuit are formed. The protection circuit composed of the NOT gate or the AND gate device of the present invention can keep the positive terminal of the electrolytic capacitor always in the disconnected state when the electrolytic capacitor is wired incorrectly, and will not put it into the circuit, and light the light-emitting diode to provide the protection circuit. A prompt is issued to avoid capacitor damage, explosion and even life and property safety accidents caused by reverse connection of electrolytic capacitors.

Description

A protection circuit for reverse connection of polar electrolytic capacitors by using NOT gate or AND gate

technical field

The invention relates to a protection circuit for reverse connection of polar electrolytic capacitors, more particularly, to a protection circuit for reverse connection of polar electrolytic capacitors by using a NOT gate or an AND gate.

Background technique

There are positive pins and negative pins on the polar electrolytic capacitors. Do not connect them wrongly when using them, otherwise the polar electrolytic capacitors will be damaged. This is determined by the structure and composition of the electrolytic capacitors. The electrolytic capacitors contain Electrolyte materials that store charge, if the direction of the current applied to it is not correct, not only will it not be able to store the charge, but it will also cause damage.

In the process of electronic experiment teaching, students who do electrical work will use electrolytic capacitors in the laboratory. For example, in the process of power filter experiment teaching, students need to connect electrolytic capacitors by themselves, so as to deepen students' understanding of the working principle and working characteristics of electrolytic capacitors. understanding and mastery. In the actual experiment process, there will always be some students who reversely connect the positive and negative electrodes of the electrolytic capacitor. After the reverse connection, the electrolytic capacitor will be damaged in light, and the electrolytic capacitor will explode in serious cases. Therefore, it is particularly important to develop a circuit with reverse connection protection of electrolytic capacitors. Alarm signal to remind wiring errors to avoid electrolytic capacitor damage, explosion and accidents caused by personal safety and property damage. The AND gate and the NOT gate are commonly used devices in digital logic operations, which can be used to detect and alarm the reverse connection of polar electrolytic capacitors.

SUMMARY OF THE INVENTION

In order to overcome the shortcomings of the above-mentioned technical problems, the present invention provides a protection circuit for realizing reverse connection of a polar electrolytic capacitor by using a NOT gate or an AND gate.

The protection circuit for reverse connection of polarized electrolytic capacitors is realized by using a NOT gate of the present invention, including the capacitor terminal JP1, the polarized electrolytic capacitor E1 and the protection circuit for reversed connection of capacitors, E1 is protected and used to connect to other circuits There are polar electrolytic capacitors, the capacitor terminal JP1 is composed of two terminals, and the positive and negative electrodes of E1 are connected with the capacitor connection terminal JP1; it is characterized in that: the capacitor reverse connection protection circuit is composed of NOT gate U1A, NOT gate U1B , NOT gate U1C, transistor Q1, relay JDQ1, light-emitting diode LED1, DC power supply circuit and diodes D1, D2, D3 and D4. The positive pole of the polar electrolytic capacitor E1 is connected to the normally open point of the relay JDQ1 and the capacitor terminal JP1. One terminal is connected, the negative terminal of E1 is connected to the other terminal of JP1, the positive terminal of E1 is connected to the input terminal of the NAND gate U1A through the normally open point of JDQ1 and the resistor R1, and the negative terminal of E1 is connected to the NAND gate of the resistor R2. The input terminals of U1C are connected to each other; the DC power supply circuit is used to provide DC voltage Vcc; the input terminals of the U1A and U1C are connected to the power supply ground through the resistor R3 and the resistor R4 respectively, and the anode of the diode D1 is connected to the input terminal and the cathode of the U1C. It is connected to the positive pole of the power supply Vcc, the positive pole of D2 is connected to the input terminal of U1A, the negative pole is connected to the positive pole Vcc of the power supply; the positive pole of D3 is connected to the power supply ground, the negative pole is connected to the input terminal of U1A, the positive pole of D4 is connected to the power supply ground and the negative pole Connected to the input of U1C;

The output terminal of U1A is connected with the input terminal of U1B, the output terminal of U1B is connected to the base of the transistor Q1 through the resistor R6, Q1 is an NPN type transistor, the emitter of the transistor Q1 is connected to the power ground, and the collector of Q1 It is connected in series with the relay JDQ1 and then connected to the positive side of the power supply; the output end of the NOT gate U1C is connected to the positive side of the power supply through the resistor R5 and the light-emitting diode LED1 in sequence.

In the present invention, a non-gate is used to realize the protection circuit for reverse connection of polar electrolytic capacitors. The full-bridge rectifier circuit formed by D9 consists of the primary side of the transformer TB1 is connected to the AC mains, the secondary side is connected to the input end of the full-bridge rectifier circuit, and the positive pole of the output end of the full-bridge rectifier circuit is connected to the three-terminal voltage regulator tube PV1. At the input end, the output end of the three-terminal voltage regulator tube PV1 forms the positive electrode Vcc of the power supply; the electrolytic capacitor E3 is arranged at the output end of the full-bridge rectifier circuit, and the electrolytic capacitor E2 is arranged at the output end of the three-terminal voltage regulator tube PV1.

In the present invention, a non-gate is used to realize the protection circuit for reverse connection of polar electrolytic capacitors. Both ends of the coil of the relay JDQ1 are connected in parallel with a freewheeling diode D5 to prevent the self-inductance voltage generated by it from being too high. The anode of the diode D5 is connected to On the collector of the transistor Q1 and on the positive pole of the negative power supply.

The protection circuit for reverse connection of polar electrolytic capacitors is realized by using a NOT gate of the present invention. The resistance values of the resistor R1 and the resistor R2 are both 20kΩ, the resistance values of the resistor R3 and the resistor R4 are both 100kΩ, and the resistance values of the resistor R5 and the resistor R6 are both 100kΩ. The resistance value is 4.7kΩ.

The protection circuit for reverse connection of polar electrolytic capacitors is realized by the AND gate of the present invention, including the capacitor terminal JP2, the polar electrolytic capacitor E4 and the protection circuit for reverse connection of capacitors. E4 is a protected circuit for connecting to other circuits. There are polar electrolytic capacitors, there are two terminals on the capacitor terminal JP2, and the positive and negative electrodes of the polar electrolytic capacitors are respectively connected with the two terminals on JP2; it is characterized in that: the capacitor reverse connection protection circuit is composed of AND gate U2A, AND gate U2B, transistor Q2, light-emitting diode LED2, relay JDQ2, DC power supply circuit and diodes D10, D11, D12 and D13, the positive pole of polar electrolytic capacitor E4 is connected to the normally open point of relay JDQ2 and JP2. One terminal is connected, the negative terminal of E4 is connected to the other terminal of JP2, the positive terminal of E4 is connected to the two input terminals of the AND gate U2A through the normally open point of the relay JDQ2 and the resistor R7 in turn, and the negative terminal of E4 is connected to the two input terminals of the AND gate U2A through the resistor. R8 is connected to the two input terminals of the AND gate U2B; the two input terminals of U2A and the two input terminals of U2B are connected to the power ground through the resistor R9 and the resistor R10 respectively, and the anode of the diode D10 is connected to the two input terminals of U2B , the negative pole is connected to the positive side of the power supply, the positive pole and negative pole of D11 are respectively connected to the two input terminals of U2A and the positive pole of the power supply, the positive pole and negative pole of D12 are connected to the two input terminals of U2A, and the positive pole and negative pole of D13 are connected to the two input terminals of U2A respectively. On the power ground and the two input terminals of U2B;

The output terminal of the AND gate U2A is connected to the base of the transistor Q2 through the resistor R11, Q2 is an NPN type transistor, the emitter of the transistor Q2 is connected to the power ground, and the collector is connected to the power supply. The positive electrode is connected in series with the coil of the relay JDQ2 , and the output end of the AND gate U2B is connected to the power ground through the resistor R12 and the light-emitting diode LED2 in turn.

The protection circuit for reverse connection of polar electrolytic capacitors is realized by the AND gate of the present invention. The full-bridge rectifier circuit formed by D18 is composed. The primary side of the transformer TB2 is connected to the AC mains, the secondary side is connected to the input end of the full-bridge rectifier circuit, and the positive pole of the output end of the full-bridge rectifier circuit is connected to the three-terminal voltage regulator tube PV2. The input end, the output end of the three-terminal voltage regulator tube PV2 forms the positive electrode Vcc of the power supply; the electrolytic capacitor E6 is set at the output end of the full-bridge rectifier circuit, and the electrolytic capacitor E5 is set at the output end of the three-terminal voltage regulator tube PV2.

In the present invention, an AND gate is used to realize the protection circuit for reverse connection of polarized electrolytic capacitors. The two ends of the relay JDQ2 coil are connected in parallel with a freewheeling diode D14 to prevent the self-inductance voltage generated by it from being too high. The positive electrode of the diode D14 is connected to On the collector of the transistor Q2 and on the positive pole of the negative power supply.

In the present invention, the protection circuit for reverse connection of polar electrolytic capacitors is realized by using an AND gate. The resistance value is 4.7kΩ.

The beneficial effects of the present invention are as follows: the protection circuit for the reverse connection of the polar electrolytic capacitor is realized by the NOT gate of the present invention. , transistor Q1, relay JDQ1, light-emitting diode LED1 and DC power supply circuit. When JP1 does not connect E1 to the experimental circuit or although it is connected to the experimental circuit but the experimental circuit is not powered on, the input terminals of U1A and U1C are respectively connected by resistance R3 and R4 are pulled to low level, U1C outputs high level so that LED1 is not lit, U1A outputs high level after U1B outputs low level, Q1 is turned off so that the electromagnetic coil of JDQ1 is not energized, E1 is not connected to the experimental circuit ; When JP1 is wrongly connected to the experimental circuit, the input terminal of U1A is low level, the input terminal of U1C is high level, and U1C outputs low level to light up LED1 to remind the experimenter that the wiring of E1 is wrong, U1B Output low level, Q1 is off, so that the electromagnetic coil of JDQ1 is not energized, E1 is not connected to the experimental circuit, and the protection of E1 is realized; when JP1 is wired correctly, the U1A input terminal is high level, and the U1C input terminal is low level. , U1C outputs a high level to make Q1 turn on, Q1 turns on to make the coil of JDQ1 energized, and then E1 is connected to the experimental circuit, U1C outputs a high level, and the light-emitting diode LED1 does not light up.

The protection circuit for reverse connection of polar electrolytic capacitors is realized by an AND gate of the present invention, which includes a polar electrolytic capacitor E1, a capacitor terminal JP2, an AND gate U2A, an AND gate U2B, a transistor Q2, a relay JDQ2, a light-emitting diode LED2 and a DC The power supply circuit is composed. When JP2 does not connect E4 to the experimental circuit or although it is connected to the experimental circuit but the experimental circuit is not powered, the input terminals of U2A and U2C are pulled to low potential by resistors R9 and R10 respectively, and U2B outputs low power. If it is flat, LED2 will not be lit, U2A will output low level, Q2 will be cut off so that the electromagnetic coil of JDQ2 will not be energized, and E4 will not be connected to the experimental circuit; when JP2 is incorrectly connected to the experimental circuit, the input of U2A will be low level. , the input of U2B is high level, U2B outputs high level to light LED2 to remind the experimenter that the wiring of E4 is wrong, U2B outputs low level, Q2 is cut off, so that the electromagnetic coil of JDQ2 is not energized, and E4 is not connected to the experiment The circuit realizes the protection of E4; when the JP2 wiring is correct, the U2A input terminal is high level, the U2B input terminal is low level, the U2A output high level makes Q2 conduct, and Q2 conducts to make the coil of JDQ2 energized, Then connect E4 to the experimental circuit, U2B outputs a low level, and the light-emitting diode LED1 does not light up.

It can be seen that whether it is a protection circuit with a polarity electrolytic capacitor reversely connected by a NOT gate device or an AND gate device, when the electrolytic capacitor to be protected is mistakenly connected to other experimental circuits, the positive end of the electrolytic capacitor can always be maintained. In the disconnected state, it will not be put into the circuit, and the light-emitting diode is lit to give a prompt, which avoids the capacitor damage, explosion and even life and property safety accidents caused by the reverse connection of the electrolytic capacitor.

Description of drawings

Fig. 1 is the circuit diagram that realizes the protection circuit with polarity electrolytic capacitor reverse connection with NOT gate of the present invention;

FIG. 2 is a circuit diagram of a protection circuit for reversely connecting a polarized electrolytic capacitor with an AND gate according to the present invention.

In Figure 1: 1 capacitor terminal JP1, 2 polar electrolytic capacitor E1, 3 NOT gate U1A, 4 NOT gate U1B, 5 NOT gate U1C, 6 transistor Q1, 7 relay JDQ1, 8 transformer TB1, 9 three-terminal regulator Tube PV1, 10 light-emitting diodes LED1.

In Figure 2: 11 capacitor terminal JP2, 12 polar electrolytic capacitor E4, 13 AND gate U2A, 14 AND gate U2B, 15 light-emitting diode LED2, 16 triode Q2, 17 relay JDQ2, 18 transformer TB2, 19 three-terminal voltage regulator Tube PV2.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and embodiments.

Embodiment 1, as shown in Figure 1, provides a circuit diagram of the invention of using a NOT gate to realize a protection circuit for reverse connection of a polar electrolytic capacitor, which consists of a capacitor terminal JP1 (1), a polar electrolytic capacitor E1 ( 2) It is composed of a capacitor reverse connection protection circuit. The capacitor terminal JP1 consists of two terminals (the labels are 1 and 2 respectively). The terminal of E1 is directly connected to the terminal marked 2 on JP1. E1 is a protected polar electrolytic capacitor used to connect to other experimental circuits, and JP1 is used to connect E1 to other circuits.

Capacitor reverse connection protection circuit consists of NOT gate U1A (3), NOT gate U1B (4), NOT gate U1C (5), transistor Q1 (6), relay JDQ1 (7), light-emitting diode LED1 (10), DC power supply circuit and Diodes D1, D2, D3 and D4 are composed of diodes D1, D2, D3 and D4. The input terminal of the NOT gate U1A is connected to the No. 1 terminal of JP1 through the resistor R1, and the input terminal of U1C is connected to the No. 2 terminal of JP2 through the resistor R2. The resistor R1 and the resistor The resistance value of R2 is relatively large (for example, 20kΩ is used), so as to play the role of current limiting isolation and ensure that E1 will not have a destructive effect on the reverse capacitor protection circuit after it is connected to the experimental circuit through JP1. The DC power circuit is used to provide stable DC power, and the positive pole of the DC power is Vcc.

The anode and cathode of diode D1 are connected to the input terminal of U1C and the anode of the power supply respectively, the anode and cathode of D2 are respectively connected to the anode of U1A and the anode of the power supply, and the anode and cathode of D3 are respectively connected to the power supply ground and the input terminal of U1A , the positive and negative poles of D4 are respectively connected to the power ground and the input terminal of U1C. D1 and D2 play the role of high-level clamps, and D3 and D4 play the role of low-level clamps. When E1 is reversely connected via JP1 and the voltage applied to the positive pole of D1 is greater than Vcc (at least 0.7V greater than Vcc), D1 is turned on so that the potential at the input of U1C is not higher than Vcc+0.7V, and D3 is turned on so that the voltage at the input of U1A will not be lower than -0.7V; when E1 is correctly connected, the voltage applied to the positive electrode of D2 is greater than Vcc (at least higher than When Vcc is greater than 0.7V), D2 is turned on so that the voltage at the input end of U1A will not exceed Vcc+0.7V, and D4 is turned on so that the voltage at the input end of U1C will not be lower than -0.7V, so as to ensure the normal operation of the NOT gates U1A and U1C.

The input terminals of the NOT gates U1A and U1C are connected to the power supply ground through the resistor R3 and the resistor R4 respectively. When JP1 is not connected to other experimental circuits or is connected to other experimental circuits but the experimental circuit is not powered, R3 and R4 respectively connect the NOT gates. The potentials at the U1A and U1C inputs are pulled low.

The output end of the NOT gate U1A is connected to the input end of the NOT gate U1B, the output end of U1B is connected to the base of the transistor Q1 through the resistor R6, Q1 is an NPN transistor, the emitter of the transistor Q1 is connected to the power ground, and the The collector is connected in series with the coil of the relay JDQ1 and then connected to the positive pole of the power supply to control the energization and de-energization of the coil of the relay JDQ1 by using the on and off of Q1. In order to avoid the self-induced high voltage generated by the relay JDQ1 at the moment of power failure, the diode D5 is connected in parallel with the two ends of the relay JDQ1 to play a freewheeling function. The output terminal of the shown NOT gate U1C is connected to the positive pole of the power supply through the resistor R5 and the light-emitting diode LED1 in turn. When the light-emitting diode LED1 lights up, it indicates that the wiring of E1 is wrong, and reminds the experimenter to change the connection mode of the positive and negative poles of E1.

The DC power supply circuit consists of a full-bridge rectifier circuit formed by a transformer TB1 (8), a three-terminal voltage regulator tube PV1 (9), an electrolytic capacitor E2, an electrolytic capacitor E3 and diodes D6, D7, D8 and D9. The primary side of the transformer TB1 Connected to the AC mains, the secondary side is connected to the input end of the full-bridge rectifier circuit, the positive pole of the output end of the full-bridge rectifier circuit is connected to the input end of the three-terminal voltage regulator tube PV1, and the output end of the three-terminal voltage regulator tube PV1 forms the power supply The positive electrode is Vcc; the electrolytic capacitor E3 is set at the output end of the full-bridge rectifier circuit, and the electrolytic capacitor E2 is set at the output end of the three-terminal voltage regulator tube PV1, and E3 and E2 realize filtering and voltage regulation.

When the transformer TB is connected to the power supply, the capacitor reverse connection protection circuit of the present invention starts to work.

When JP1 is not connected to other experimental circuits or although it is connected to other experimental circuits but the experimental circuit is not energized: resistors R3 and R4 pull the input terminals of the NOT gates U1A and U1C to the ground potential respectively. Since the input terminal of U1A is low potential, Its output side is high potential, after U1B inversion, U1B outputs low potential, transistor Q1 is turned off, the electromagnetic coil of relay JDQ1 is not energized, the normally open contact of JD1 does not act, and the protected capacitor E1 is not connected to the experimental circuit; , Since the U1C input terminal is low potential, its output terminal side is high potential, the two ends of the indicator light are equipotential, so the light-emitting diode LED1 will not emit light. Therefore, at this time, the polar electrolytic capacitor E1 will not be put into the external circuit, and the error indicator will not light up:

When JP1 is connected to the experimental circuit in a wrong way and the experimental circuit is powered on: the current formed by the external experimental circuit forms a loop through R2, R4, D3, and R1, and a positive and negative voltage is formed at both ends of R4. If the voltage is higher than Vcc If there are many, it will be clamped to the voltage of Vcc+0.7V by D1, so that the potential of the U1C output terminal = 0, and the indicator LED1, which marks the wrong wiring of E1, will light up. At this time, the input terminal of U1A is subjected to a voltage of -0.7V, and the output terminal of U1A is high level. After U1B inverts the phase, U1B outputs a low level, which makes Q1 cut off, and the relay JDQ does not operate, so the capacitor E1 cannot be put into use, so it protects the E1.

When JP1 is connected to the experimental circuit in the correct way and the experimental circuit is energized: the current formed by the external experimental circuit forms a loop through R1, R3, D4, and R2, and a positive and negative voltage is formed at both ends of R3. If the voltage is higher than Vcc For many, it will be clamped to the voltage of Vcc+0.7V by D2, so that the potential of the U1A output terminal = 0, after U1B inversion, the Q1 is turned on, the relay JDQ is activated, so the capacitor E1 is put into the circuit. At this time, the input terminal of U1B is subjected to a voltage of -0.7V, so that the output terminal of U1B is at a high potential, and the two ends of the error indicator LED are equipotential, so it will not emit light.

Embodiment 2, as shown in FIG. 2, provides a circuit diagram of the present invention using an AND gate to realize a protection circuit for reverse connection of a polar electrolytic capacitor, which consists of a capacitor terminal JP2 (11), a polar electrolytic capacitor E4. (12) It is composed of a capacitor reverse connection protection circuit. E1 is a protected polar electrolytic capacitor used to connect to other experimental circuits. The capacitor terminal JP2 is used to connect E1 to other circuits. JP2 has the label of For the two terminals of 1 and 2, the positive pole of E4 is connected to the No. 1 terminal of JP2 through the normally open point of the relay JDQ2, and the negative pole of E4 is directly connected to the No. 2 terminal of JP2. Capacitor reverse polarity protection circuit consists of AND gate U2A (13), AND gate U2B (14), light-emitting diode LED2 (15), transistor Q2 (16), relay JDQ2 (17), DC power supply circuit and diodes D10, D11, D12 and It consists of D13, and the two input terminals of the AND gate U2A are shorted together, and the two input terminals of U2B are also shorted together.

The two input terminals of the AND gate U2A are connected to the No. 1 terminal of JP2 through the resistor R7, and the two input terminals of U2B are connected to the No. 2 terminal of JP2 through the resistor R8. R7 and R8 use larger resistance values (such as All use 20kΩ) resistors to play the role of current limiting isolation to ensure that E2 will not have a destructive effect on the reverse capacitor protection circuit after it is connected to the experimental circuit through JP2. The DC power circuit is used to provide stable DC power, and the positive pole of the DC power is Vcc. The input terminal of AND gate U2A and the input terminal of AND gate U2B are respectively connected to the power supply ground through resistor R9 and resistor R10. When JP2 is not connected to other experimental circuits or is connected to other experimental circuits but the experimental circuit is not powered, R9 and R10 pulls the potentials at the input terminals of the AND gate U2A and the AND gate U2B to a low level, respectively.

Similarly, the anode and cathode of diode D10 are connected to the input terminal of U2B and the anode of the power supply respectively, the anode and cathode of D11 are respectively connected to the anode of U2A and the anode of the power supply, the anode and cathode of D12 are respectively connected to the power supply ground and the input of U2A The positive and negative terminals of D13 are connected to the power ground and the input terminal of U2B respectively. D10, D11 play a high-level clamp, D12, D13 play a low-level clamp, when E2 is reversely connected via JP2 and the voltage applied to the positive pole of D10 is greater than Vcc (at least 0.7V greater than Vcc), D10 is turned on so that the potential of the U2B input terminal is not higher than Vcc+0.7V, and D12 is turned on so that the voltage of the U2A input terminal will not be lower than -0.7V; when E1 is correctly connected, the voltage applied to the positive electrode of D11 is greater than Vcc (at least higher than Vcc). When Vcc is greater than 0.7V), D11 is turned on so that the voltage at the input end of U2A will not exceed Vcc+0.7V, and D13 is turned on so that the voltage at the input end of U2B will not be lower than -0.7V to ensure the normal operation of the AND gates U2A and U2B.

The output terminal of the AND gate U2A is connected to the base of the transistor Q2 through the resistor R11. Q2 is an NPN type transistor. The emitter of the transistor Q2 is connected to the power supply ground, and the collector is connected in series with the coil of the relay JDQ2 and then connected to the positive pole of the power supply. The on and off of the coil of the relay JDQ2 is controlled by the on and off of the transistor Q2. In order to avoid the self-inductive high voltage of the coil of the relay JDQ2 at the moment of power failure, a freewheeling diode D14 is connected in parallel at both ends. The anode of the diode D14 is connected to the collector of Q2, and the cathode is connected to the power supply. The output end of the AND gate U2B is connected to the power ground through the resistor R12 and the light-emitting diode LED2 in turn. The light-emitting diode LED2 lights up to indicate that there is a wiring error of the polar electrolytic capacitor E4 to remind the experimenter to correct it.

In this embodiment, the DC power supply is composed of a transformer TB2 (18), a three-terminal voltage regulator PV2 (19), an electrolytic capacitor E5, an electrolytic capacitor E6 and a full-bridge rectifier circuit formed by diodes D15, D16, D17 and D18. The DC power supply circuit is the same as that in Embodiment 1, but the labels of the components are different.

When the transformer TB2 is connected to the power supply, the capacitor protection circuit in this embodiment starts to work.

When JP2 is not connected to other experimental circuits or although it is connected to other experimental circuits but the experimental circuit is not powered on: resistors R9 and R10 respectively pull the input terminals of AND gate U2A and AND gate U2B to ground potential (low level), U2A outputs low potential, Q2 is off, the electromagnetic coil of JDQ2 is not energized, the normally open contact of JDQ2 does not operate, and the protected capacitor E4 is not connected to the experimental circuit; at the same time, since the input terminal of U1B is low potential, its output terminal is also low Potential, the two ends of the indicator LED2 are equipotential, so they will not emit light. Therefore, the capacitor E4 will not be put into the external circuit at this time, and the error indicator LED2 will not light up:

When JP2 is connected to the experimental circuit in a wrong way and the experimental circuit is energized: the current formed by the external experimental circuit forms a loop through R8, R10, D12, and R7, and both R10 form a positive and negative voltage. If the voltage is higher than Vcc For many, the U2B output terminal will be clamped to the voltage of Vcc+0.7V by D10, so that the U2B output terminal presents a high potential, and the indicator LED2, which indicates the wiring error of E4, will light up. At this time, the input terminal of U2A is subjected to a voltage of -0.7V, and the output terminal of U2A is low level, which makes Q2 cut off, and the relay JDQ2 does not operate, so the capacitor E4 cannot be put in, so E4 is protected.

When JP1 is connected to the experimental circuit in the correct way and the experimental circuit is powered on: the current formed by the external experimental circuit forms a loop through R1, R9, D13, and R8, forming a positive and negative voltage at both ends of R9. If the voltage is higher than Vcc Many, the U1A input terminal will be clamped to the voltage of Vcc+0.7V by D11, so that the U2A output terminal presents a high potential, so that Q2 is turned on, and the relay JDQ2 operates, so the capacitor E4 is put into the circuit. At this time, the input terminal of U2B bears a voltage of -0.7V, so that the output terminal of U2B is low potential, and the two ends of the error indicator LED2 are equipotential, so it will not emit light.

Claims (8)

1. A protection circuit for reverse connection of polar electrolytic capacitors with a NOT gate, including capacitor terminal JP1 (1), polar electrolytic capacitor E1 (2) and a reverse capacitor protection circuit, E1 is protected It is used to connect the polar electrolytic capacitors in other circuits. The capacitor terminal JP1 consists of two terminals, and the positive and negative electrodes of E1 are connected to the capacitor connection terminal JP1; it is characterized in that: the capacitor reverse connection protection circuit is composed of NOT gate U1A (3), NOT gate U1B (4), NOT gate U1C (5), transistor Q1 (6), relay JDQ1 (7), light-emitting diode LED1 (10), DC power supply circuit and diodes D1, D2, D3 and D4, the positive pole of the polar electrolytic capacitor E1 is connected to one terminal of the capacitor terminal JP1 through the normally open point of the relay JDQ1, the negative pole of E1 is connected to the other terminal of JP1, and the positive pole of E1 is connected to the other terminal of JDQ1. The normally open point and resistor R1 are connected to the input end of the NOT gate U1A, and the negative electrode of E1 is connected to the input end of the NOT gate U1C through the resistor R2; the DC power supply circuit is used to provide the DC voltage Vcc; the input ends of the U1A and U1C The diode D1 is connected to the power supply ground through the resistor R3 and the resistor R4 respectively, the positive pole of the diode D1 is connected to the input terminal of U1C, the negative pole is connected to the positive pole Vcc of the power supply, the positive pole of D2 is connected to the input terminal of U1A, and the negative pole is connected to the positive pole Vcc of the power supply; The positive pole of D3 is connected to the power ground, the negative pole is connected to the input terminal of U1A, the positive pole of D4 is connected to the power supply ground, and the negative pole is connected to the input terminal of U1C; The output terminal of U1A is connected with the input terminal of U1B, the output terminal of U1B is connected to the base of the transistor Q1 through the resistor R6, Q1 is an NPN type transistor, the emitter of the transistor Q1 is connected to the power ground, and the collector of Q1 It is connected in series with the relay JDQ1 and then connected to the positive side of the power supply; the output end of the NOT gate U1C is connected to the positive side of the power supply through the resistor R5 and the light-emitting diode LED1 in sequence. 2. The protection circuit for realizing reverse connection of polar electrolytic capacitors with a NOT gate according to claim 1, wherein the DC power supply circuit consists of a transformer TB1 (8), a three-terminal voltage regulator PV1 (9) , electrolytic capacitor E2, electrolytic capacitor E3 and a full-bridge rectifier circuit formed by diodes D6, D7, D8 and D9. The primary side of the transformer TB1 is connected to the AC mains, and the secondary side is connected to the input of the full-bridge rectifier circuit. The positive pole of the output terminal of the full-bridge rectifier circuit is connected to the input terminal of the three-terminal regulator tube PV1, and the output terminal of the three-terminal regulator tube PV1 forms the positive pole Vcc of the power supply; the electrolytic capacitor E3 is set at the output terminal of the full-bridge rectifier circuit, and the electrolytic capacitor E2 is set At the output of the three-terminal voltage regulator PV1. 3. The protection circuit for realizing reverse connection of polar electrolytic capacitors with a NOT gate according to claim 1 or 2, characterized in that: the two ends of the coil of the relay JDQ1 (7) are connected in parallel with a self-inductance to prevent it from being generated. The freewheeling diode D5 with too high voltage, the anode of the diode D5 is connected to the collector of the transistor Q1 (6) and the anode of the cathode power supply. 4. according to claim 1 and 2, realize the protection circuit that has polarity electrolytic capacitor reverse connection with non-gate, it is characterized in that: the resistance value of described resistance R1 and resistance R2 is 20kΩ, resistance R3 and resistance R4 The resistance values of the resistors are both 100kΩ, and the resistance values of the resistor R5 and the resistor R6 are both 4.7kΩ. 5. A protection circuit for reverse connection of polar electrolytic capacitors with an AND gate, including capacitor terminal JP2 (11), polar electrolytic capacitor E4 (12) and a protection circuit for reverse connection of capacitors, E4 is protected The polar electrolytic capacitor used to connect to other circuits has two terminals on the capacitor terminal JP2, and the positive pole and the negative pole of the polar electrolytic capacitor are respectively connected with the two terminals on JP2; it is characterized in that: The capacitor reverse connection protection circuit is composed of AND gate U2A (13), AND gate U2B (14), transistor Q2 (16), light-emitting diode LED2 (15), relay JDQ2 (17), DC power supply circuit and diodes D10, D11, D12 and D13, the positive pole of the polar electrolytic capacitor E4 is connected to one terminal of JP2 through the normally open point of the relay JDQ2, the negative pole of E4 is connected to the other terminal of JP2, and the positive pole of E4 is in turn connected to the normal terminal of the relay JDQ2. The open point and resistor R7 are connected to the two input terminals of the AND gate U2A, and the negative electrode of E4 is connected to the two input terminals of the AND gate U2B through the resistor R8; the two input terminals of U2A and the two input terminals of U2B are respectively connected by Resistor R9 and resistor R10 are connected to the power supply ground, the positive pole of diode D10 is connected to the two input terminals of U2B, the negative pole is connected to the positive pole of the power supply, the positive pole and negative pole of D11 are respectively connected to the two input terminals of U2A and the positive pole of the power supply, D12 The positive pole and negative pole of D13 are connected to the two input terminals of U2A, and the positive pole and negative pole of D13 are respectively connected to the power ground and the two input terminals of U2B; The output terminal of the AND gate U2A is connected to the base of the transistor Q2 through the resistor R11, Q2 is an NPN type transistor, the emitter of the transistor Q2 is connected to the power ground, and the collector is connected to the power supply. The positive electrode is connected in series with the coil of the relay JDQ2 , and the output end of the AND gate U2B is connected to the power ground through the resistor R12 and the light-emitting diode LED2 in turn. 6. The protection circuit for realizing reverse connection of polar electrolytic capacitors with an AND gate according to claim 5, wherein the DC power supply circuit is composed of a transformer TB2 (18), a three-terminal voltage regulator PV2 (19) , electrolytic capacitor E5, electrolytic capacitor E6 and a full-bridge rectifier circuit formed by diodes D15, D16, D17 and D18. The primary side of transformer TB2 is connected to the AC mains, and the secondary side is connected to the input of the full-bridge rectifier circuit. The positive pole of the output terminal of the full-bridge rectifier circuit is connected to the input terminal of the three-terminal regulator tube PV2, and the output terminal of the three-terminal regulator tube PV2 forms the positive pole Vcc of the power supply; the electrolytic capacitor E6 is set at the output terminal of the full-bridge rectifier circuit, and the electrolytic capacitor E5 is set at the output of the three-terminal voltage regulator PV2. 7. The protection circuit for realizing reverse connection of polar electrolytic capacitors with an AND gate according to claim 5 or 6, characterized in that: the two ends of the coil of the relay JDQ2 (17) are connected in parallel with a self-inductance to prevent it from being generated. The freewheeling diode D14 with too high voltage, the anode of the diode D14 is connected to the collector of the transistor Q2 (16) and the anode of the negative power supply. 8. according to claim 5 or 6, realize the protection circuit that has polarity electrolytic capacitor reverse connection with AND gate, it is characterized in that: the resistance value of described resistance R7 and resistance R8 are 20kΩ, resistance R9 and resistance R10 The resistance values of the resistors are both 100kΩ, and the resistance values of the resistor R11 and the resistor R12 are both 4.7kΩ.

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