Abstract: The present invention provides embodiments of a musical instrument preamplifier. It is especially suited to acoustic and electric guitars and basses. All components, including the power source, are contained within or on the body of the instrument. The preamplifier dubbed BPTD (for Battery Powered Tube Driver) contains a vacuum tube input stage and may utilize a second stage consisting of either a vacuum tube or semiconductor device, such as a JFET. Circuitry is included to bias the cathode heater and the preamplifier circuit with no dangerous high voltages present. The tube may be mounted on the instrument body to provide for a pleasing display.

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: There is provided a tube amplifier comprising a first vacuum tube K3 having a plate applied with a positive voltage and a cathode applied with a negative voltage by a first resistor, a second vacuum tube K4 having a grid connected to the cathode of the first vacuum tube and a cathode or a heater applied with a voltage close to a potential of zero in relation to a plate voltage, and an output transformer TF1 having a first coil and a second coil which is connected to a loud-speaker, said first coil having a terminal connected to the plate of the second vacuum tube and another terminal applied with a positive voltage. Also, time means is used to optimally maintain the grid voltage of the second vacuum tube when the power source is turned on, and the plate voltage of another vacuum tube K1 provided in a preceding stage of the first vacuum tube is controlled to maintain the negative voltage applied to the grid of the second vacuum tube at a desired value.

Abstract: There is provided a tube amplifier comprising a first vacuum tube K3 having a plate applied with a positive voltage and a cathode applied with a negative voltage by a first resistor, a second vacuum tube K4 having a grid connected to the cathode of the first vacuum tube and a cathode or a heater applied with a voltage close to a potential of zero in relation to a plate voltage, and an output transformer TF1 having a first coil and a second coil which is connected to a loud-speaker, said first coil having a terminal connected to the plate of the second vacuum tube and another terminal applied with a positive voltage. Also, timer means is used to optimally maintain the grid voltage of the second vacuum tube when the power source is turned on, and the plate voltage of another vacuum tube K1 provided in a preceding stage of the first vacuum tube is controlled to maintain the negative voltage applied to the grid of the second vacuum tube at a desired value.

Abstract: Field emission devices are cascaded in multiple stages, such that certain structures function as electrodes for field emission devices of differing stages.

Abstract: An audio amplifier including a non-inverting amplifier stage that provides linear amplification without loop feedback for low distortion audio systems. The amplifier stage includes a triode vacuum tube or a triode connected pentode vacuum tube and a P channel field effect transistor (FET). The vacuum tube and the FET are connected in a series combination in which the source of the FET is connected to the cathode of the tube through a suitable resistance. The drain of the FET is connected to a negative voltage and both the gate of the FET and the grid of the tube are at DC ground potential. The input signal to be amplified is fed into the gate of the FET and the output is taken from the plate of the tube which is supplied with a positive voltage through a suitable load. In most applications the grid of the tube is connected to ground, however in some applications the grid may serve as an extra inverting input.

Abstract: The IF amplifier combines the high frequency and low noise figure characteristics of a cascode stage with the large signal handling capability and accurate gain control of a direct emitter coupled amplifier controlled by a constant current source. The amplifier uses a technique of alternately stacked cascode stages which results in minimizing both the total current drain and the value of DC potential necessary to operate the amplifier. A current mirror, independent of power supply variation, is used to control the gain of the amplifier and is also used to provide temperature compensation for amplifier gain. Special bias techniques along with the current mirror minimize the variation of the amplifier gain with respect to DC power supply variations. Novel use of semiconductor devices minimizes the number of leadout connections on an I.C. chip needed for attaching large external bypass capacitors.