Abstract: A method and an apparatus for operating an electronic sensor and an electronic user input are provided. In one configuration, the apparatus includes a detection circuit configured to recognize a user input voltage generated by an electronic user input and a power supply configured to supply power to a detection circuit continuous without polling. In another configuration, the apparatus includes a port, a first power supply, a second power supply, and a control circuit configured to selectively couple the first power supply or the second power supply to the port based on a state of operation of an electronic sensor coupled to the port.

Abstract: A vacuum tube amplifier is formed of a vacuum tube having a cathode, a plate, a grid, and a heater to radiate electrons from the cathode. An input signal is supplied to the plate, an output signal is obtained at the grid, and a predetermined low voltage is supplied to the heater. The voltage supplied to the heater can be low, thereby significantly decreasing an overall consumption of electric power for the vacuum tube amplifier.

Abstract: A vacuum tube amplifier is formed of a vacuum tube having a cathode, a plate, a grid, and a heater to radiate electrons from the cathode. An input signal is supplied to the plate, an output signal is obtained at the grid, and a predetermined low voltage is supplied to the heater. The voltage supplied to the heater can be low, thereby significantly decreasing an overall consumption of electric power for the vacuum tube amplifier.

Abstract: An operational amplifier (33) is continuously switched back-and-forth between an auto-zero mode of operation and an accurate amplification mode of operation. During the auto-zero mode of operation, the junction between an offset voltage compensation (e.g., auto-zero) capacitor (35) and the noninverting input of the operational amplifier (33) is referenced to the input signal voltage via a bootstrap amplifier (31), rather than being tied to ground. Further, during the auto-zero mode of operation, the other end of the auto-zero capacitor (35) is referenced to the output of the operational amplifier (33), which is also connected to the inverting input of the operational amplifier. As a result, the auto-zero capacitor (35) is charged to a voltage level equal to the input offset voltage of the operational amplifier, but in polarity opposition thereto.