Patent ID: 7408401

Claim:
A vacuum tube replacement device that is arranged for use in a vacuum tube socket that includes a plate terminal, a grid terminal, a cathode terminal, and two filament terminals, the vacuum tube replacement device comprising: a power supply means that is arranged to generate a local power supply from two filament terminals associated with the vacuum tube socket; and an amplifier means that is operated from the local power supply to generate a first signal at the plate terminal and a second signal at the cathode, wherein the first and second signals are responsive to an input signal received from the grid terminal, the amplifier means comprising: a variable control means that includes a first input that is coupled to the grid terminal, a second input that is arranged to receive a feedback signal, and an output terminal that is arranged to provide a control signal in response to the feedback signal and the input signal; a feedback network that is coupled between the plate terminal and the second input of the variable control means, wherein the feedback network is arranged to provide the feedback signal; and a high voltage buffer that is coupled to the plate terminal and responsive to the control signal, wherein the high voltage buffer is automatically biased, wherein the variable control means is configured such that an idle current associated with the high voltage buffer is dynamically adjusted according to a self-biasing scheme.