Abstract: An electric amplifier useful for instance in simulators for strong electric signals, comprising several partial amplifiers so connected and voltage fed that they will amplify an interval each of the input voltage. Every partial amplifier comprises at least one amplification component and two gates, of which gates one is blocking those potentials applied to the component that are less than a given first value but is open for potentials exceeding said value while the other gate is open for potentials less than a given second value greater than said first value but is blocking the component for potentials exceeding said second value.

Abstract: An emitter follower type power amplifier capable of changing over supply voltage and hence the load line, comprising: an amplifying transistor of saturating type; at least a first and a second supply voltage source; a switching transistor having, a collector connected to the first supply voltage source, and an emitter connected to the second supply voltage source via a diode and also to the collector of said power amplifying transistor; a load resistor connected between the emitter of the power amplifying transistor and the ground; and a biasing voltage source connected between the base of the switching transistor and the emitter of the power amplifying transistor. This power amplifier circuit arrangement allows switching-over between load lines for small signal region and large signal region thereby enabling large signal amplification and reducing the collector loss of the power amplifying transistor. This circuit arrangement is also used in a push-pull power amplifying circuit to obtain the same advantage.

Abstract: An amplifier circuit suitable for use as a video amplifier in a color television circuit for driving the variable impedance load provided by a color television picture tube, in which the load impedance of the amplifier element of the circuit is also made variable. This is achieved, in one embodiment by using as the output stage of the amplifier two transistors with a complementary symmetrical configuration so that one is always substantially cut-off while the other conducts. In another embodiment a transistor in common collector configuration acts as the amplifier element and its emitter from which the output of the amplifier is taken is connected by a diode to the collector of a transistor which feeds the base of the common collector transistor.

Abstract: An audio frequency power amplifier wherein an input signal is applied to respective input electrodes of a pair of transistors of the same conductivity type to produce an output signal at an output electrode of one of the pair of transistors. A common electrode of the one transistor is connected with an output electrode of the other transistor and a power from a first D.C. power supply is supplied to the junction thereof through a diode while a power is supplied to a common electrode of the other transistor from a second D.C. power supply having a higher voltage than that of the first D.C. power supply. The other transistor and the diode are alternately rendered conductive and non-conductive in response to the signal level of the input signal, a capacitor is connected to the input electrode of the other transistor, which capacitor is charged during the turn-off of the other transistor whereby the charge is supplied to the other transistor upon turning on of the other transistor to shorten the rise time.

Abstract: A power amplifier circuit comprising a voltage amplifier stage and a current amplifier stage, the mode of bias of which can be changed over between class A and class B (AB). The supply voltage for the current amplifier stage is changed over by a mode selection switch. The change in the supply voltage is detected to select the bias voltage for the current amplifier stage.The possibility of applying a class A bias to the current amplifier stage supplied with a class B line voltage is thus completely removed.

Abstract: A low distortion audio amplifier utilizes a pair of field effect transistors connected in a balanced source follower configuration. A tapped inductor connected between the sources of the field effect transistors provides inductive coupling between the sources and maintains the sources at the same direct current potential. This permits the voice coil of a loud speaker to be connected directly across the sources without causing excessive direct current to flow through the voice coil.

Abstract: The amplifier comprises at least two amplifier units or transistors T.sub.1 and T.sub.2 of complementary types. The base of the first transistor T.sub.1 is connected to a control current supply line. The emitter of the transistor T.sub.1 is connected on the one hand to one end of the load impedance and on the other hand to the base of the second transistor T.sub.2. The collector of the transistor T.sub.1 is connected to a voltage supply of suitable polarity. The emitter of the transistor T.sub.2 is connected to the current supply line and the collector of said transistor is connected to another end of the load impedance.

Abstract: An audio power amplifier can be operated in either class A, class B or class AB amplifier modes by selectively switching bias values set in a bias setting circuitry provided for a driver stage which drives the main power amplifier stage.

Abstract: A transistor amplifier circuit comprising a pair of complementary transistors having collectors connected to each other through a resistor and to an output terminal through respective capacitors, emitters connected to a positive and a negative supply voltage respectively and bases connected to the collectors thereof through respective resistors and to an input terminal through respective capacitors. In this amplifier circuit, the emitter circuits of the paired-transistors include no resistors and accordingly no by-pass capacitors, thus eliminating thermal noise sources and also voltage drop due to such resistors. Therefore, this amplifier circuit can be operated at a markedly reduced S/N ratio with a very low supply voltage, giving a high utility of voltage. Such amplifier circuit can have a very simplified structure.

Abstract: A power amplifier with an automatic bias control circuit is disclosed. The amplifier includes two complementary Darlington pairs operating in a push-pull mode providing output power. A bias control network including a switching transistor is coupled to the base circuits of the Darlington pairs for controlling the bias current delivered to the pairs. The transistor is switched on and off by a detecting circuit which senses the presence of input signals applied to the amplifier. The bias control network operates to minimize power consumption by the Darlington pairs when no input signal is present and to raise the bias level of the Darlington pairs without distortion in the output signal when an input is applied to the amplifier.

Abstract: A class-AB audio amplifier comprises, as a final stage, two complementary power transistors connected across a direct-current source in series with an output resistor whose junction with the first of these transistors is grounded through a capacitor. The bases of the power transistors are connected across a biasing resistance inserted between two complementary pilot transistors which are connected across the d-c source in series with a constant-current generator, one of these pilot transistors having its base connected to a signal input while the other forms part of a differential circuit also including a feedback transistor of the same conductivity type connected across the source in series with the constant-current generator.

Abstract: The maximum drive currents available to the output transistors of a Class B or AB push-pull amplifier are controlled as a function of their emitter-to-collector voltages, permitting the operation of the transistors over substantially their entire safe operating area ratings.

Abstract: An amplifier comprises a power amplifying circuit including FET's and operable when supplied with a first power source and a drive circuit operable when supplied with a second power source for driving the power amplifying circuit and including a bias circuit for providing bias voltages for the FET's. Upon turning on the power switch, the first power source builds up quickly while the second power source builds up with some time delay. Switch-over circuits connect the power lines of the drive circuit to the first power source initially and to the second power source after the build-up of the latter, thereby starting the supply of the bias voltages to the FET's at the build up of the first power source to prevent an excessively large current or rush current from flowing through the FET's, thus avoiding the breakage or characteristic deterioration of the FET's.