reverse 1999 circuit puzzle

The following are a few types of circuits to prevent reverse power supply: 1. ** Diode-proof reverse connection circuit **: A single circuit is connected in series to the power supply input end. By using the one-way conductivity of the circuit, it can conduct in the forward direction and cut off in the reverse direction. When the power supply was reversed, the LED would not conduct, thus avoiding reverse power supply. However, during normal operation, a voltage drop of 0.7V will occur on the LED, which is not suitable for circuits with strict requirements on the supply voltage. 2. ** Fuse + Parallel Diode **: The principle is also based on the one-way conductivity of the Diode. When the power supply is connected normally, the LED does not work, and the current flows into the circuit through the fuse. After the power supply is connected in reverse, the LED is instantly turned on, causing the positive and negative poles of the power supply to be short-circuited. The short-circuit current generated by the short-circuit fuses the fuse, achieving the effect of reverse connection protection. However, the fuse selection must be compatible with the circuit characteristics. 3. ** Full-bridge Rectifiers Anti-reverse Connection Circuit **: No matter what the input power is, the output is always fixed, so it can work regardless of the positive and negative connection circuit. However, when it works, the full-bridge rectify will produce a voltage drop of about 1.5V. 4. ** Low internal resistance of the anti-reverse connection circuit of the upheaval protector **: When the power supply is normally connected, the upheaval protector is turned on. After the power supply is reversed, the upheaval protector is turned off to achieve reverse connection protection. Due to factors such as the improvement of the process technology, the internal resistance of the semiconductor was extremely small, and the impact on the voltage drop and power consumption of the circuit was minimal. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>

The inverse proportional operation circuit was actually a deep voltage parallel negative feedback circuit. In an ideal situation, the potential at the inverted input is zero (that is, the "virtual ground"), and the common-mode voltage added to the input of the integrated operational amplifier is very small. The output voltage is proportional to the input voltage, but the phase is opposite, thus achieving an inverse proportional operation. The scaling factor depended on the ratio of the resistance, and had nothing to do with the internal parameters of the integrated operational amplifier. As long as the resistance values of the resistance were accurate and stable, an accurate scaling relationship could be obtained. The scaling factor could be greater than, equal to, or less than 1. Due to the deep voltage parallel negative feedback, the input resistance of the circuit was not high, and the output resistance was very low. In terms of Multisim simulation, you can double-click the icon of the scope to adjust the X-axis scan to 500 fs/Di or 1ms/DIV, the A channel amplitude to 10 millivolts/Div, and the B channel amplitude to 100 millivolts/Div. Turn on the power switch, and you can observe the inverse relationship between the output and input signals. At the same time, you can see the multiple relationship from the amplitude of the wave and the channel gain. The amplification can also be measured with an AC voltage meter, and the relationship between R3 and the ratio is R3=R1//R, A = R1/R2. The inverse proportional amplifier can realize the inverse amplification of the input signal. It has a wide application prospect in signal processing, filter and other applications. This function can be easily realized with the LM324. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>

In the circuit diagram for measuring the reverse characteristics of the circuit, the circuit was connected in the reverse direction, that is, the positive pole of the power supply was connected to N, and the negative pole was connected to P. In this connection method, the direction of the external electric field was the same as the direction of the internal electric field of the junction, which would strengthen the internal electric field, making the thickness of the depletion layer wider and the space charge larger. This made it more difficult for the holes in the P region and the free electrons in the N region to pass through the junction, and the current was greatly reduced. At this time, the current through the junction was mainly drift current. Since the concentration of minority carriers does not change when the temperature is constant, the reverse current does not change with the applied voltage within a certain range. This current is called the reverse saturation current. In the measuring circuit, by changing the size of the variable resistance, the reverse current flowing through the LED under different values of terminal voltage could be measured, thereby depicting the reverse characteristic curve of the LED. From the perspective of the V-A characteristic curve of the LED, the bottom left part is the reverse characteristic part, which can be used to analyze the relevant data and phenomena in the reverse characteristic measurement circuit of the LED, such as the reverse breakdown voltage and other parameters. When the reverse voltage exceeds a certain value, the reverse current will suddenly increase, and this voltage value is the reverse breakdown voltage. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>

The following is a basic method to draw a positive and negative ladder diagram and circuit diagram: ** 1. Confirm control requirements and I/O allocation ** 1. ** Clear control requirements ** - Usually, the forward and reverse control required the motor to rotate forward, reverse, and stop through buttons, and it had to be interlocked with forward and reverse (to prevent short circuits caused by forward and reverse rotation at the same time). It might also require thermal relay for overload protection and other functions. 2. **I/O allocation confirmed ** - ** Inputs **: For example, the start button for forward rotation, the start button for reverse rotation, the stop button, and the overload protection signal of the thermal relay are all used as input signals. These input signals should be distributed to the corresponding input terminal of the PC. For example, in the case of the Mitsui PC, it may be X000, X001, etc., and in the case of the siemen PC, it may be I0.0, I0.1, etc. - ** Outputs **: Forward Contactor Coils and Reverse Contactor Coils are used as the output devices. They should be connected to the corresponding output terminal of the PC, such as Y000 and Y001 of the Mitsubishi-based PC, Q0.0 and Q0.1 of the SIEMEN-based PC, etc. ** 2. Draw the circuit diagram (Take the three-phase induction motor as an example)** 1. ** Main circuit part ** - The three-phase power supply was connected to the fuse (for short-circuit protection) and then connected to the main contact of the contactors. For forward rotation, when the main contact of the forward rotation contactors (KM1) is closed, the three-phase power supply is connected to the motor according to the normal phase sequence, and the motor is rotated forward. For reversal, when the main contact of the reversal contactors (KM2) is closed, the phase sequence of two phases of the three-phase power supply is reversed and then connected to the motor, and the motor is reversed. At the same time, the thermal relay (FT) should be connected to the circuit to detect the current of the motor and automatically cut off the circuit when overloaded. 2. ** Control Circuit ** - ** Forward control circuit **: Lead out from one end of the power supply, first connect the stop button (normally closed), then connect the forward start button (normally open) and the auxiliary normally open contact (for self-locking) of the forward rotating contactors (KM1) in series, then connect the auxiliary normally closed contact (for interlocked) of the reversing contactors (KM2) in series, and finally connect to the coil of the forward rotating contactors (KM1). The other end of the coil returns to the other end of the power supply. - ** Reverse control circuit **: It is also led out from one end of the power supply. First, connect the stop button (normally closed), then connect the reverse start button (normally open) and the auxiliary normally open contact of the reversing contactors (KM2) in series (for self-locking), then connect the auxiliary normally closed contact of the forward rotating contactors (KM1) in series (for interlocked), and finally connect to the coil of the reversing contactors (KM2). The other end of the coil returns to the other end of the power supply. - ** Overload protection part **: The normally closed contact of the thermal relay (FT) is connected in series to the common part of the control circuit (i.e. behind the stop button). When the motor is overloaded, the thermal relay will act, and the normally closed contact will be disconnected, cutting off the entire control circuit. ** 3. Draw the ladder diagram (Take the SIEMens's PL as an example)** 1. ** Forward Rotation Control Logics ** - I0.0 is used as the input signal of the forward start button, I0.1 is used as the input signal of the stop button, I0.2 is used as the input signal of the reverse start button (all are normally open contact input), Q0.0 is used as the output signal of the forward contact coil, and Q0.1 is used as the output signal of the reverse contact coil. - When I0.0 is pressed (the normally open contact is closed) and I0.1 is not pressed (the normally closed contact is closed) and Q0.1 is not energized (the normally closed contact is closed), Q0.0 is energized and self-locked (the normally open contact of Q0.0 is closed to maintain its energized state). - In the ladder diagram, it is represented as: the normally closed contacts of I0.0 and I0.1, the normally closed contact of Q0.1 are connected in series to the coil of Q0.0, and the normally open contact of Q0.0 is connected in parallel with I0.0 to achieve self-locking. 2. ** Reverse control logic ** - When I0.2 is pressed (the normally open contact is closed) and I0.1 is not pressed (the normally closed contact is closed) and Q0.0 is not energized (the normally closed contact is closed), Q0.1 is energized and self-locking. - In the ladder diagram, it is represented as: the normally closed contacts of I0.2 and I0.1, the normally closed contact of Q0.0 are connected in series to the coil of Q0.1, and the normally open contact of Q0.1 is connected in parallel with I0.2 to achieve self-locking. The specific instructions, component representation, and programming rules of different brands of PDLCs (e.g., Samsung, SIEMENS, etc.) may differ, but the basic control logic and design ideas are similar. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>

The double-interlocked positive and negative rotation control circuit includes a double-interlocked contactors and buttons. The following are its main components and functions: 1. Air switch (QL): used to switch on and off the power supply. It has short-circuit, serious overload and undervoltage protection functions. 2. Fuse (FO): for short-circuit protection. 3. Contactor (KO): Able to frequently switch on and off large currents. Has arc extinguishing function and also has undervoltage protection function. 4. Thermo relay (FT): Overload protection. 5. Push button (SS): Control the start and stop of the circuit. The working principle was as follows: 1. Forward rotation control: press down the SSB2, the SSB2 normally closed contact will first break the KM2 interlocked (cut off the reverse rotation control circuit), the KM1 coil will be energized, the KM1 self-locking contact will close and self-lock, the KM1 main contact will close, the KM1 interlocked contact will break the KM2 interlocked (cut off the reverse rotation control circuit), and the motor will start to rotate continuously forward. 2. Reverse rotation control: press down on SSB3. SSB3 normally closed contacts will be cut off first. KM1 coil will lose power, KM2 coil will be energized, KM2 self-locking contacts will be closed and self-locking contacts will be closed. KM2 main contacts will be closed, and the KM2 interlocked contacts will be cut off and interlocked with KM1 (cutting off the forward rotation control circuit). The motor will start to rotate continuously. 3. Stop: No matter in the forward or reverse working state, as long as you press the button, the entire control circuit will lose power, the contactors will reset, and the motor will stop running. In terms of connection: 1. First, label the blueprint, and then connect the actual object according to the blueprint. In the case of unfamiliarity, it was best to connect the secondary line one circuit at a time. 2. The circuit could be checked by the buzzing bar of the Multimeter, which was also a resistance bar that could measure the resistance of the coil of the contact. It should be noted that in order to ensure safety and normal operation, the graphic symbols and text symbols of each component must be accurately understood during operation and connection, and their structure and functions must be mastered. At the same time, it was necessary to accurately grasp the concepts of electrical self-locking (relying on the normally open electric shock of the contactors to keep its coil energized), electrical interlocked (only one of the two contactors was allowed to be energized at the same time), and mechanical interlocked (only one of the two contactors was allowed to work through a pair of normally open and normally closed buttons). <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>

This isn't related to the novel, but I can briefly tell you the key points of the positive and negative circuit connection of the three-phase induction motor. Three-phase induction motor to achieve positive and negative transfer line, mainly by changing the phase sequence of the motor three-phase power supply to achieve. Generally, two contactors would be used. The three-phase power supply of one of the contactors would be connected in the normal order, such as A-B- C. The three-phase power supply of the other contactors would be changed to C-B- A. In terms of the control circuit, it should be interlocked to prevent the two contactors from short-circuiting at the same time. However, this was just a simple introduction. The actual connection must be strictly in accordance with the electrical safety regulations. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>

The reverse rotation control circuit was a circuit used to control the forward and reverse rotation of the motor. The working principle was as follows: - ** Contactor Interlock Positive and Negative Rotation Control Circuit **: - ** Forward Rotation **: Press the Forward Rotation Start button (such as SSB2), and the coil of the Forward Rotation Contactor (such as Km1) will be energized. The Km1 auxiliary normally open contact is closed to achieve self-locking, ensuring that the circuit remains connected after the button is released; the Km1 auxiliary normally closed contact is disconnected and interlocked with the reversing contact (Km2) coil to prevent simultaneous power-on. At the same time, the main contact of Km1 was closed, and the motor was powered up and began to rotate forward. - ** Reverse **: Press the reverse start button (like SSB3), and the Km2 coil will be energized. The Km2 auxiliary normally open contact is closed and self-locked, and the Km2 auxiliary normally closed contact is disconnected, causing the Km1 coil to lose power (forming an interlocked). The Km1 main contact is reset, the Km2 main contact is closed, and the motor runs in reverse. - ** Double Interlock Positive and Negative Rotation Control Circuit of the Button-Contactor **: Add the Button-Contactor Interlock to the Contactor Interlock. The normally closed contact of the reverse start button is connected in series with the coil of the contactors that control the forward rotation, and the normally closed contact of the forward start button is connected in series with the coil of the contactors that control the reverse rotation. This was equivalent to double insurance, further ensuring that the positive and reverse contactors would not be energized at the same time, improving the safety and reliability of the circuit. The principle of the positive and negative rotation control in the ladder diagram was similar: - Two start-stop circuits were used to control the forward and reverse rotation of the motor. Pressing the forward start button (such as SSB2), the corresponding input point (such as X0) will turn ON, and its normally open contact will be connected, so that the coil of the output point (such as Y0) will be "energized" and self-protect, so that the coil of the forward rotating contactors (such as KM1) will be energized, and the motor will rotate forward. - Pressing the stop button (such as SSB1), the corresponding input point (such as X2) will turn ON, and its normally closed contact will be disconnected, causing the coil of the forward output point (such as Y0) to "lose power" and the motor will stop running. - In order to ensure that the forward and reverse rotation do not work at the same time, the normally closed contacts of the forward rotation output point (such as Y0) and the reverse rotation output point (such as Y1) are connected in series with each other's coil to achieve interlocked connection; and the button is interlocked, that is, the normally closed point of the reverse rotation start button is connected in series with the coil of the output point (such as Y0) that controls the forward rotation, and the normally closed contact of the forward rotation start button is connected in series with the coil of the output point (such as Y1) that controls the reverse rotation. In this way, when the motor was rotating forward, if it wanted to change to reverse operation, it could directly press the reverse start button without pressing the stop button, and through the switching of the contacts, it could realize forward transformation and reverse rotation. In addition, there are often overload protection components in the circuit, such as thermal relay (FT). When the induction motor is seriously overloaded for a long time, after a certain delay, the thermal relay will act, and its normally closed contact will be broken. When it is connected in series with the coil of the contactors, it can make the coil of the contactors cut off, and the motor will stop running, playing a protective role. Some thermal relay needed to be manually reset, and some had an automatic reset function. During the circuit connection and use, the connection position of the contacts needed to be reasonably arranged according to its characteristics to ensure safe operation. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>

The working principle of the three-phase induction motor reverse connection control circuit is as follows: 1. Reverse braking was completed with the help of the speed relay SD. There was a heavy object in the speed relay mechanically connected to the motor shaft. 2. After pressing the start button, the motor of the SSB1 rotated to a certain speed. Due to the inertia, the weight pressed the speed relay micro-switch to send a signal, and the SD contact was connected. 3. When the stop button SSB0 is pressed, the KM1 loses power, and the motor enters the free parking state instantly after being disconnected from the power supply; after the normally closed contact of the KM1 recovers, the KM2 is energized, and the motor enters the braking state after being connected with the reverse power supply; when the speed of the motor drops and is lower than the speed at which the speed relay contacts are pressed together, the speed relay micro switch is disconnected, and the motor enters the free parking state again until it completely stops. 4. For KM1 and KM2, AC contactors with mechanical interlocks shall be selected, and their normally closed contacts shall be set with electrical interlocks to ensure safety. 5. Circuit breakers QF1 and QF2 are used for short-circuit protection, and thermal relay KH is used for long-term overload protection of the motor. 6. The resistance R was used to adjust the brake strength. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>

In an amplifier circuit, a circuit with feedback was called a closed-loop circuit. The feedback amplifier circuit had a feedback path from the output to the input. This feedback circuit was in a closed-loop state, so the feedback amplifier circuit was a closed-loop circuit. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>