(under subclass 127) Subject matter wherein the "combined control means" is in the circuit from the power supply or bias voltage source means to the anode or screen grid electrode of a vacuum tube amplifying device or in shunt therewith, in such manner, as to control the power supply or bias voltage applied to the anode or screen grid electrode.
(1) Note. Ordinary anode or screen grid resistors as such are not control means such as is classified in this subclass. However glow tubes, nonlinear resistors, diodes, vacuum tubes, etc.., in the anode or screen grid supply circuit for voltage regulation and related subject matter are classified herein. Such matter involving ordinary resistors or other nonlinear impedances in the power or bias supply circuits are classified in the appropriate coupling subclass, when the particular nonlinear element affects the signal coupling, and not the power supply. Subject matter wherein such impedance is isolated from the signal path or is involved only in the power supply circuit or forms the means for isolating the power supply circuit and is not involved in signal coupling as, for example, signal by-pass means for the power supply, classification is in the appropriate subclass indented under subclass 199 below.
(2) Note. Nonlinear impedances, vacuum tube impedances, thermal impedances, etc.., in amplifier circuits as indicated are classified in this class. See the search notes below.
SEE OR SEARCH THIS CLASS, SUBCLASS:
52, for pilot frequency control means which may utilize thermal or other nonlinear control means.
70+, for series energized vacuum tube amplifier devices having the anode energized through the discharge path of a
controlled vacuum tube. 86, for signal feedback amplifiers having a variable impedance in the feedback path.
95, and 110, for nonlinear impedance in the cathode impedance feedback path and for a nonlinear impedance element in the loop path of feedback amplifiers respectively.
96, for feedback amplifiers combined with control of bias voltage of the signal amplifier.
123, for control of anode or screen grid voltage in push-pull amplifiers.
131, for amplifiers having a bias control voltage applied to an electrode separate and distinct from the signal input electrode.
143, for a thermally responsive impedance in the amplifier circuit (when not specifically involved in power or bias supply circuit as in subclass 128).
144+, for variable impedance for the signal channel, controlled by a separate control path, particularly subclass 145 where the variable impedance is an electron tube or a diode.
164, for amplifier interstage coupling including an electronic tube or diode.
174, for amplifiers having an electromechanical transducer (e.g., piezoelectric crystal) in an interstage coupling circuit.
183, for amplifiers having a nonlinear device in a D.C.. interstage coupling.
254, and 278+, for semiconductor amplifiers including nonlinear impedance elements used for signal volume level control.
256, 272 and 289, for semiconductor amplifiers including transistor temperature control. 290, for semiconductor amplifiers having bias control D.C.. feedback stabilization which may involve nonlinear impedance elements.
291, for semiconductor signal feedback amplifiers which may involve nonlinear impedance elements.
296, 297, for semiconductor cascaded amplifiers series energized for power involving bias or power supply circuitry.
299+, for semiconductor amplifiers combined with a
