Abstract: A balun structure is provided. The balun structure includes a substrate, a first coil structure and a second coil structure having a spiral shape and on the substrate. The first coil structure includes a first single-layer coil surrounding by first laminated coils that are connected to the first single-layer coil. The second coil structure can include a second single-layer coil and second laminated coils that are connected to the second single-layer coil. A projection of the first single-layer coil and a projection of the second single-layer coil on a surface of the substrate overlap with each other. A number of the second laminated coils is larger than or equal to a number of the first laminated coils. The second laminated coils are arranged alternately with the first laminated coils or the first single-layer coil in a plane parallel to the surface of the substrate.

Abstract: A multi-power supply system and a control method thereof are disclosed. The multi-power supply system includes a first power-supply unit, a second power-supply unit, a switching unit, and a control unit. The power-supply unit comprises a reverse current prevention circuit, a converter circuit, and an input circuit. The switching unit is electrically coupled to the first power-supply unit and the second power-supply unit. When the first and second input circuits are in normal operation, the control unit controls the switching unit to be turned off to allow the first power-supply unit and the second power-supply unit to supply power to a load. When one of the first and second input circuits is in abnormal operation, the control unit controls the switching unit to be turned on. The switching unit cooperates with the first and second reverse current prevention circuits to achieve the switching of input.

Abstract: A resonant converter apparatus includes a first pre-regulator, a first resonant converter, a second pre-regulator, a second resonant converter and a controller. The first pre-regulator receives a first input voltage and generates a first output voltage. The first resonant converter receives the first output voltage and generates a supply voltage. The second pre-regulator receives a second input voltage and generates a second output voltage. The second resonant converter receives the second output voltage and generates the supply voltage, in which an output of the second resonant converter is electrically connected in parallel with an output of the first resonant converter. The controller controls the first pre-regulator and the second pre-regulator such that the first resonant converter and the second resonant converter generate identical output currents in accordance with controlled operations of the first pre-regulator and the second pre-regulator.

Abstract: A cooling device includes a cooler. The cooler includes a base, a plurality of cooling fins secured to the base, and a heat pipe inserting through the cooling fins. Each cooling fin includes a fin body and a pressed portion extending from the fin body. The fin body includes a hole area, which defines a receiving hole. A portion of the heat pipe extends through the receiving hole; the pressed portion includes at least one guiding portion, which is configured to guide air to flow towards the hole area from the fin body.

Abstract: One aspect of the present invention, a strip type off-circuit tap changer includes an insulating rod and a support, where an operation positioning device is arranged on the support, a rack mobile frame is disposed on the insulating rod, the rack of the rack mobile frame is engaged to a drive gear of the operation positioning device, columnar fixed contacts are longitudinally arranged at a spacing on the insulating rod, the rack mobile frame is connected to a moving contact frame, and a moving contact assembly is arranged on the moving contact frame and fits with the fixed contacts on the insulating rod, the moving contact assembly is formed by an annular moving contact and an elastic pin, and the annular moving contact spans between two adjacent columnar fixed contacts.

Abstract: In one aspect of the invention, an off-circuit tap changer includes a switch base and a rotation shaft penetrating the switch base. An upper end of the rotation shaft is connected to an operation positioning device, a lower end of the rotation shaft is disposed with moving contacts, and fixed contacts corresponding to the moving contacts are circumferentially disposed at a spacing on the switch base; the moving contacts are radial elastic rolling moving contacts, and the radial elastic rolling moving contacts span between two adjacent fixed contacts and closely contact the fixed contacts.

Abstract: A multi-power supply system and a control method thereof are disclosed. The multi-power supply system includes a first power-supply unit, a second power-supply unit, a switching unit, and a control unit. The power-supply unit comprises a reverse current prevention circuit, a converter circuit, and an input circuit. The switching unit is electrically coupled to the first power-supply unit and the second power-supply unit. When the first and second input circuits are in normal operation, the control unit controls the switching unit to be turned off to allow the first power-supply unit and the second power-supply unit to supply power to a load. When one of the first and second input circuits is in abnormal operation, the control unit controls the switching unit to be turned on. The switching unit cooperates with the first and second reverse current prevention circuits to achieve the switching of input.

Abstract: A supporting apparatus, configured to support a heat dissipating device, includes a bracket, two adjusting structures, and two mounting portions. Each of the two mounting portions defines a mounting hole. Each of the two adjusting structures is engaged in each of the mounting holes and includes an adjusting member and an installation member engaged with the adjusting member. Each of the adjusting members defines a through hole. The two adjusting members are rotatable relative to the two mounting portions from a first position to a second position. When the adjusting members are in the first position, a first line is running through the two through holes. When the adjusting members are in the second position, a second line is running through the two through holes, and a length of the first line is less than a length of the second line.

Abstract: A resonant converter apparatus includes a first pre-regulator, a first resonant converter, a second pre-regulator, a second resonant converter and a controller. The first pre-regulator receives a first input voltage and generates a first output voltage. The first resonant converter receives the first output voltage and generates a supply voltage. The second pre-regulator receives a second input voltage and generates a second output voltage. The second resonant converter receives the second output voltage and generates the supply voltage, in which an output of the second resonant converter is electrically connected in parallel with an output of the first resonant converter. The controller controls the first pre-regulator and the second pre-regulator such that the first resonant converter and the second resonant converter generate identical output currents in accordance with controlled operations of the first pre-regulator and the second pre-regulator.

Abstract: A heat dissipation system includes an enclosure, a first heat sink, a second heat sink, and a fan. The enclosure includes a bottom plate, a first side plate, and a second side plate. A first air vent area is located on the first side plate. A second air vent area is located on the second side plate. A first heat generation apparatus and a second heat generation apparatus is mounted on the bottom plate and located between the first air vent area and the second air vent area. A first heat sink is mounted on the bottom plate and contacts the first heat generation apparatus. A second heat sink is mounted on the bottom plate and contacts the second heat generation apparatus. A plurality of second fins is located on the second heat sink. Each second fin is wavy. A fan is located between the first air vent area and the second air vent area. The fan is adapted to drive air to flow through the first air vent area, the first heat sink, the plurality of second fins, and the second air vent area.

Abstract: A fan control system for a fan on a motherboard includes an I/O controller installed on the motherboard and a control circuit electrically connected to the I/O controller. The fan includes a motor and a rotation speed detecting chip. The I/O controller outputs a rotation speed control signal and a pulse width modulation (PWM) signal. The rotation speed detecting chip detects a rotation speed of the fan, and outputs a rotation speed feedback signal according to the rotation speed of the fan. The I/O controller receives the rotation speed feedback signal, and adjusts a duty cycle of the PWM signal accordingly to change the rotation speed of the fan. The control circuit receives the rotation speed control signal, and outputs a fan driving signal accordingly. The motor receives the fan driving signal, and drives the fan to rotate in a direction according to the fan driving signal.

Abstract: A MEMS microphone includes a cover, a housing engaging with the cover for forming a cavity, at least one transducer accommodated in the cavity, and a conductive case covering the cover and the sidewall of the housing. The housing includes a cover and a sidewall extending from the base. The conductive case defines a first part covering the cover, a second part extending from the first part for covering the sidewall and a third part perpendicularly extending from the second part for covering a periphery part of the base, the third part forming an opening.

Abstract: A heat dissipation system includes a computer case has a base plate and a back plate, a heat sink, a second heat source, and an air partition panel. The back plate defines a plurality of first air outlet holes aligned with the heat sink, and a plurality of second air outlet holes aligned with the second heat source. The heat sink is positioned on the base plate in contact with a first heat source. The second heat source is positioned on the base plate adjacent to the base plate. The air partition panel is positioned on the base plate between the motherboard and the second heat source. A first air path is defined between the air partition panel and the plurality of first air outlet holes. A second air path is defined between the air partition panel and the plurality of second air outlet holes.

Abstract: On aspect of the present invention, a strip type off-circuit tap changer includes an insulating rod and a support, where an operation positioning device is arranged on the support, a rack mobile frame is disposed on the insulating rod, the rack of the rack mobile frame is engaged to a drive gear of the operation positioning device, columnar fixed contacts are longitudinally arranged at a spacing on the insulating rod, the rack mobile frame is connected to a moving contact frame, and a moving contact assembly is arranged on the moving contact frame and fits with the fixed contacts on the insulating rod, the moving contact assembly is formed by an annular moving contact and an elastic pin, and the annular moving contact spans between two adjacent columnar fixed contacts.

Abstract: An electronic device comprises a cooler comprises a plurality of first locking members, a backboard defining pluralities of first and second positioning holes, and a circuit board. The backboard is attached to the cooler through the first locking members engaged with the second positioning holes. A first mounting member and a second mounting member are adapted to receive the heat generating component. The first mounting member defines a plurality of locking holes. The first positioning holes are among the second positioning holes. The second mounting member receives the heat generating component, the circuit board is between the second mounting member and the backboard, the first mounting member is secured to the circuit board; when the first mounting member receives the heat generating component, the circuit board is between the first mounting member and the backboard, the first mounting member is secured to the backboard.

Abstract: In one aspect of the invention, an off-circuit tap changer includes a switch base and a rotation shaft penetrating the switch base. An upper end of the rotation shaft is connected to an operation positioning device, a lower end of the rotation shaft is disposed with moving contacts, and fixed contacts corresponding to the moving contacts are circumferentially disposed at a spacing on the switch base; the moving contacts are radial elastic rolling moving contacts, and the radial elastic rolling moving contacts span between two adjacent fixed contacts and closely contact the fixed contacts.

Abstract: A heat sink includes a contact portion, a first support rib, a second support rib, a third support rib and a fourth support rib radially extended from the contact portion, and a plurality of parallel fins radially extended from the first support rib, the second support rib, the third support rib and the fourth support rib between two adjacent support ribs. The contact portion contacts with a first heat source. A distance from the contact portion to an edge of the plurality of parallel fins between the first support rib and the second support rib is a first distance. A distance from the contact portion to an edge of the plurality of parallel fins between the third support rib and the fourth support rib is a second distance. The first distance is less than the second distance.

Abstract: An exemplary data storage device cage includes a main body and an electrical connector positioned on the main body. The main body includes a rectangular flat plate and two side plates respectively extending upward from opposite edges of the flat plate. The flat plate has at least a pair of tabs opposite to each other. The at least two tabs are respectively contiguous with but offset inward from the two side plates and positioned to cooperatively hold a data storage device therebetween. The electrical connector is positioned between the two side plates for electrically connecting the data storage device to an external device.

Abstract: A fan speed control circuit includes a first fan, a second fan, a first temperature sensor, a second temperature sensor, a PWM regulator, and a driving module. The first temperature sensor senses a temperature of the first component to generate a first temperature signal. The second temperature sensor senses a temperature of a second component to generate a second temperature signal. The PWM regulator is connected to the first temperature sensor and the second temperature sensor. The PWM regulator generates a first PWM signal according to the first temperature signal and generates a second PWM signal according to the second temperature signal. The driving module is connected to the PWM regulator. The driving module generates a first driving voltage provided to the first fan according to the first PWM signal. The driving module also generates a second driving voltage provided to the second fan according to the second PWM signal.

Abstract: A mounting assembly includes a circuit board, a securing member and a heat dissipating device. A retainer is located on the circuit board. The securing member includes a positioning portion and a claw connected to the positioning portion. The heat dissipating device includes a base attached to the circuit board and a number of fins perpendicularly located on the base. The number of fins defines a number of first air paths and a number of second air paths substantially perpendicular to the number of first air paths. The positioning portion is received in at least one of the number of first air paths and at least one of the number of second air paths, and the claw is engaged with the retainer.