Abstract: A power converter has an output that is coupled in parallel with an energy reservoir circuit and a power supply node of an audio power amplifier. The converter can set an upper limit on its input supply current that is variable in accordance with a control input. A controller is to produce a signal, coupled to the control input of the power converter, that is responsive to a measure of input supply voltage of the power converter and either output voltage of the power converter or output power of the amplifier. Other embodiments are also described and claimed.

Abstract: A power converter has an output that is coupled in parallel with an energy reservoir circuit and a power supply node of an audio power amplifier. The converter can set an upper limit on its input supply current that is variable in accordance with a control input. A controller is to produce a signal, coupled to the control input of the power converter, that is responsive to a measure of input supply voltage of the power converter and either output voltage of the power converter or output power of the amplifier. Other embodiments are also described and claimed.

Abstract: An electronic circuit measures the torque of a motor used to drive rotatable brushes, which may be used to clean the surfaces of flat articles, such as printed circuit boards. The circuit measures the torque by determining the average power consumed by the motor. The measured torque provides the operator of the system with an indication as to whether the brushes are spaced for proper impingement upon the article being scrubbed. The invention also comprises a servomechanism which provides for automatic and continuous readjustment of the position of the brushes, relative to the flat articles, in accordance with changing motor load conditions. The invention may be used to regulate the torque of a motor which is used in many other applications.