Abstract: A power converter and control circuit are provided. The control circuit has a power controller for turning on the power switch to maintain a desired output voltage and mode selection switch provides a mode selection signal. Depending on the magnitude of an input voltage of the power converter, in which the mode selection circuit compares the input voltage of the power converter with a reference voltage, a modulation controller is configured to turn on a modulation switch to activate the capacitor according to the mode selection signal.

Abstract: A power converter includes a power switch controlling current flow in the power converter and a variable capacitance coupled in parallel to the power switch. The variable capacitance is configured to add a frequency jitter to the power converter.

Abstract: A power converter and control circuit are provided. The control circuit has a power controller for turning on the power switch to maintain a desired output voltage and mode selection switch provides a mode selection signal. Depending on the magnitude of an input voltage of the power converter, in which the mode selection circuit compares the input voltage of the power converter with a reference voltage, a modulation controller is configured to turn on a modulation switch to activate the capacitor according to the mode selection signal.

Abstract: A method for controlling a power converter includes turning on a power switch to maintain a desired output voltage, wherein the power switch is coupled to a primary winding to control a primary current flow and the output voltage is provided by a secondary winding. The method also includes adding a capacitance in parallel to the power switch at a time determined by a magnitude of an input voltage to the power converter. Here, the timing of adding the capacitance depends on the operation mode of the power controller. In a low input voltage mode, the capacitance is added in a demagnetization-time during which the secondary winding discharges. In a high input voltage mode, the capacitance is added in a discontinuous time.

Abstract: A power converter includes a power switch controlling current flow in the power converter and a variable capacitance coupled in parallel to the power switch. The variable capacitance is configured to add a frequency jitter to the power converter.

Abstract: A power converter includes a power switch controlling current flow in the power converter and a variable capacitance coupled in parallel to the power switch. The variable capacitance is configured to add a frequency jitter to the power converter.

Abstract: A method for controlling a power converter includes turning on a power switch to maintain a desired output voltage, wherein the power switch is coupled to a primary winding to control a primary current flow and the output voltage is provided by a secondary winding. The method also includes adding a capacitance in parallel to the power switch at a time determined by a magnitude of an input voltage to the power converter. Here, the timing of adding the capacitance depends on the operation mode of the power controller. In a low input voltage mode, the capacitance is added in a demagnetization-time during which the secondary winding discharges. In a high input voltage mode, the capacitance is added in a discontinuous time.

Abstract: A power converter includes a power switch controlling current flow in the power converter and a variable capacitance coupled in parallel to the power switch. The variable capacitance is configured to add a frequency jitter to the power converter.

Abstract: A leg exerciser includes a base positioned on the floor, two pedals pivotally connected to the base in a parallel manner, two spring plates supporting the pedals on the floor, each spring plate having a fixed end connected to one pedal, a free end movably supported on the floor and a smoothly arched suspension arm connected between the fixed end and the free end, and two sliding coupling devices coupled between the free ends of the spring plates and the base, each sliding coupling device including a track plate extended from the base along a predetermined path and a roller pivotally connected to the free end of one spring plate and rotatably supported on the track plate.

Abstract: A leg exerciser includes a base positioned on the floor, two pedals pivotally connected to the base in a parallel manner, two spring plates supporting the pedals on the floor, each spring plate having a fixed end connected to one pedal, a free end movably supported on the floor and a smoothly arched suspension arm connected between the fixed end and the free end, and two sliding coupling devices coupled between the free ends of the spring plates and the base, each sliding coupling device including a track plate extended from the base along a predetermined path and a roller pivotally connected to the free end of one spring plate and rotatably supported on the track plate.

Abstract: An LED lighting circuit capable of preventing thermal breakdown, including: an LED module, having a top end coupled to a line voltage; and a controller, coupled to the line voltage and a bottom end of the LED module, the controller including: an amplifier, having a positive input end coupled to an adjustable reference voltage; a transistor, having a gate terminal coupled to an output end of the amplifier, a first channel terminal coupled to the bottom end of the LED module, and a second channel terminal coupled to a negative input end of the amplifier; a current sensing resistor, coupled between the second channel terminal and a ground; and a reference voltage generator, used for generating the adjustable reference voltage according to the line voltage.

Abstract: An LED driver circuit, including: an LED load, having a top end, a middle end, and a bottom end, wherein the top end is coupled to a line voltage; and a variable load device, having a first input end, a second input end, and an output end, wherein the first input end is coupled to the middle end of the LED load for receiving a first current, the second input end is coupled to the bottom end of the LED load for receiving a second current, and the output end is for providing an output current, which equals the sum of the first current and the second current, and wherein the first current increases/decreases as the second current decreases/increases.

Abstract: A massaging shoulder exerciser includes a resilient hoop, a handle formed in a portion of the resilient hoop, and a pad formed in another portion of the resilient hoop opposed to the handle. Multiple massaging protrusions are formed on an inner surface of the pad. When in operation, the resilient hoop is disposed around a user's shoulder and the massaging protrusions are attached to an aching portion of the shoulder desired to be massaged. The user grasps the handle and further extends his upper limb to elongate the resilient hoop while overcoming resilience provided by the resilient hoop. After a suitable number of times repeating the operation, the shoulder and the upper limb are exercised and the aching portion is massaged.

Abstract: A fastening device applied to fasten a pair of handle supports on a skiing machine has an upper semi-circular clipping element which is complemented by a matching lower semi-circular clipping element to receive a bending terminal of handle support. A semi-circulr recess is provided at an external central region of the upper semi-circular clipping element, and a circular depression is provided at an external center region of the lower semi-circular clipping element. A cylindrical housing, mounted on a base of the skiing machine encases the upper and lower semi-circular clipping elements, and has two openings. A securing knob is applied to secure the upper semi-circular clipping element and the cylindrical housing together tightly, which is threaded through an opening on the cylindrical housing into the recess with a pad. A retarding bolt is disposed between the base, cylindrical housing and lower semi-circular clipping element. A spring element urges the retarding bolt to insert tightly therebetween.