Abstract: A bipolar regulated power supply employing an autotransformer to couple the output to the load is provided with a direct current feedback connected directly across the load. In this way losses in the transformer and leads connecting to the load are compensated for and direct current is eliminated from the output transformer when the input is ac coupled.

Abstract: A transistor amplifier circuitry for low level signal which employs, as the amplifying element of at least its input state circuit, a transistor having a low input resistance. Thus, this transistor amplifier circuitry has a true (not apparent) input resistance sufficiently lower than the impedance of a signal source which may be connected to the transistor amplifier circuitry. Therefore, this transistor amplifier circuitry for low level signal is capable of amplifying, with a high S/N ratio, the signal from the signal source of a low impedance.

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: 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 complementary push-pull amplifier comprising a pair of complementary transistors each of which is connected to a voltage source through a relatively large resistance and having the base biased with a voltage formed from the emitter-collector voltage of the transistor. Means for equalizing the amplitudes of second order distortion caused by the respective transistors is provided in a portion of the circuit other than the emitter circuit. The collector current is stabilized by the relatively large resistance connected to the collector and the asymmetry of the pair of transistors can be corrected by the amplitude equalizing means for cancellation of the second order distortion.

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.