Abstract: In an isolator circuit, a first differential pair circuit compares voltages of two input signals with each other, and, in accordance with the ratio of the voltages, currents flow through two resistors respectively connected to two output terminals of the first differential pair circuit. A current comparison circuit compares the currents respectively flowing through the two resistors, and outputs a voltage corresponding to a result of the comparison. A second differential pair circuit compares the voltage output from the current comparison circuit with a reference voltage, and a negative feedback is conducted so that the currents flowing through the two resistors are equal to each other. Unlike the conventional art, an isolator circuit can be configured without disposing buffer circuits.

Abstract: In an isolator circuit, a first differential pair circuit compares voltages of two input signals with each other, and, in accordance with the ratio of the voltages, currents flow through two resistors respectively connected to two output terminals of the first differential pair circuit. A current comparison circuit compares the currents respectively flowing through the two resistors, and outputs a voltage corresponding to a result of the comparison. A second differential pair circuit compares the voltage output from the current comparison circuit with a reference voltage, and a negative feedback is conducted so that the currents flowing through the two resistors are equal to each other. Unlike the conventional art, an isolator circuit can be configured without disposing buffer circuits.

Abstract: A sound field forming circuit includes a first switch portion which switchingly supplies one of an audio signals from a sound source and a second tone control circuit which variably adjusts a characteristic of a second predetermined frequency band, to a first tone control circuit which variably adjusts a characteristic of a first predetermined frequency band; a second switch portion which switchingly supplies one of the audio signals from the sound source and the first tone control circuit, to the second tone control circuit; a third switch portion which switchingly supplies one of the audio signals from the first tone control circuit and the second tone control circuit, to a front channel; and a fourth switch portion which switchingly supplies one of the audio signals from the first tone control circuit and the second tone control circuit, to a rear channel.

Abstract: A step-up power supply circuit is provided with a rectifying diode D1 to which a predetermined voltage Vcc is applied from a power supply 16, a capacitor CD1 connected in series with the rectifying diode D1, a rectifying diode D2 connected to a joint point between the rectifying diode D1 and the capacitor CD1,a capacitor CD2 connected in series with the rectifying diode D2. A trapezoidal wave signal SD produced by a triangular wave generating circuit 7, an amplifier 8, and a drive unit 9 is applied to the capacitor CD1 so as to turn ON/OFF the rectifying diodes D1 and D2. As a result, a voltage substantially equal to a voltage Vcc is produced across the capacitor CD1,and a step-up voltage HVcc approximately two times higher than the voltage Vcc is produced across the capacitor CD2. Since the rectifying diodes D1 and D2 are turned ON/OFF in response to the trapezoidal signal SD having the small RF component, the occurrence of the switching noise from the rectifying diodes D1 and D2 can be suppressed.

Abstract: A step-up power supply circuit is provided with a diode D1 to which a predetermined voltage Vcc is applied from a power supply 16, a capacitor CD1 connected to the diode D1, a diode D2 connected to a joint point between the diode D1 and the capacitor CD1,and also a capacitor CD2 connected to the diode D2. A trapezoidal wave signal SD produced by a triangular wave generating circuit 7, an amplifier 8, and a drive unit 9 is applied to the capacitor CD1 so as to turn ON/OFF the diodes D1 and D2. As a result, a step-up voltage HVcc approximately two times higher than the voltage Vcc is produced across the capacitor CD2. Amplifiers AM0 to AMn are operated under the step-up voltage HVcc produced from the step-up power supply circuit with employment of this arrangement, and the step-up voltage HVcc is judged by a judging circuit 17. As a result of this judgement, amplification factors of amplifiers AM0 to AMn are automatically and variably adjusted.

Abstract: A power supply circuit for an audio power amplifier or an amplifier of similar operation such as a motor driving amplifier.

Abstract: The present invention provides a BTL amplifier device with low power consumption and high efficiency which comprises two units of amplifier, a transistor, and a load resistor, and is driven as claimed in output from an operational amplifier as well as from an inverting amplifier. Signals at both edges of the load resistor are supplied to a differential NFB circuit and a fed-back output is inputted to one of the operational amplifiers, while an output signal from the operational amplifier is converted by an absolute value circuit, and then a DC voltage is superimposed on the absolute value signal in a voltage shifting circuit.

Abstract: A travelling toy vehicle is provided having an external body in the shape of a dump truck or other vehicle. An internal gear box, or frame, drives two wheels on an axle. The frame contains a vibrating mechanism and rocks left and right by the motion of a spur gear disposed between two cylindrical force receiving pieces attached to the external body of the travelling toy vehicle. A power transmission route change mechanism couples driver power from a motor to the vibrating mechanism for a predetermined period of time to simulate ideling of the vehicle. Thereafter, the drive power is coupled to the travelling mechanism to provide forward movement of the travelling toy vehicle. Electrical power to the motor is switched on and off by pressing down against the rear portion of the travelling toy vehicle. An operation restricting lever mounted at the rear of the vehicle prevents the switching on of electrical power when the toy is being stored and allows manual use of the toy without propulsion by the motor.

Abstract: A door pull comprises a pull member and a pair of fittings coupled with opposite ends of the pull member. The door pull is attached to a door by these fittings.

Abstract: A push-pull amplifer circuit using bipolar transistors in which non-linear distortion caused by the base-emitter voltages of the amplifying transistors of the circuit is eliminated without the use of negative AC feedback and in which variations in a DC output level at the output terminal of the amplifier are detected and fed back to the input side of the amplifier whereby the stability of the circuit at very low frequencies is remarkably improved. A first amplifier stage includes a first transistor having a base to which an input signal is applied and a second transistor the base of which is coupled to an output of the first transistor with the second transistor being of the opposite conductivity type of the first transistor. A current mirror circuit supplies currents to the first and second transistors with the currents thus supplied having a constant ratio. A second amplifying stage is provided having the same construction.

Abstract: A push-pull amplifier circuit using bipolar transistors in which non-linear distortion caused by the base-emitter voltages of the amplifying transistors of the circuit is eliminated without the use of negative AC feedback and in which variations in a DC output level at the output terminal of the amplifier are detected and fed back to the input side of the amplifier whereby the stability of the circuit at very low frequencies is remarkably improved. A first amplifier stage includes a first transistor having a base to which an input signal is applied and a second transistor the base of which is coupled to an output of the first transistor with the second transistor being of the opposite conductivity type to the first transistor. A current mirror circuit supplies currents to the first and second transistors with the currents thus supplied having a constant ratio. A second amplifying stage is provided having the same construction.

Abstract: An amplifier circuit in which the non-linear distortion of the amplifier transistors caused by non-linear base-emitter input and output characteristics is eliminated without the use of negative feedback. A first transistor and a second transistor of opposite conductivity type are coupled with the output of the first transistor connected to the base of the second transistor and with an input signal applied to the base of the first transistor. Currents are applied to the first and second transistors, such as with the current mirror circuit, in such a manner that the ratio of the currents is a predetermined constant value. Bias voltages are applied to the circuit such that the ratio of the collector-emitter voltage of the first transistor to the collector-emitter voltage of the second transistor is the reciprocal of the predetermined constant value.

Abstract: The response time of an ordinary or differential transistor switching circuit controlled by the charging of a capacitor C.sub.1 is shortened by rapidly charging the capacitor through a transistor Q.sub.6 connected in parallel with the charging resistor R.sub.1 of the capacitor. The transistor is rendered conductive before the differential switching region is reached in response to the capacitor charge reaching a predetermined level, whereby the charging curve thereafter follows a steep rise to sharply reduce the switching time.

Abstract: The response time of an ordinary or differential transistor switching circuit controlled by the charging of a capacitor C.sub.1 is shortened by charging the capacitor through a constant current source comprising a transistor Q.sub.6, a resistor R.sub.1 and diodes D.sub.1, D.sub.2, to thereby provide a sharp transfer characteristic. The charging time may be even further shortened by increasing the constant current supply at an intermediate threshold level using a further ordinary or differential transistor switching circuit, thereby providing a break in the response characteristic and increasing its slope after the threshold point.

Abstract: A muting circuit for loudspeakers is operable to disconnect a loudspeaker from an amplifier immediately upon a power supply being interrupted. The muting circuit includes an around-zero-volt detection circuit for detecting around the zero volt level of a commercial AC voltage. An RC time constant circuit is controlled by the output of the around-zero-volt detection circuit to either charge or discharge the capacitor in the RC time constant circuit only when the around zero volt level is detected. A threshold circuit is connected to the RC time constant circuit and operates a loudspeaker relay when the charge on the capacitor either exceeds or decreases below a predetermined level.

Abstract: A Schmitt trigger circuit including transistors Q12 and Q13 having a common emitter resistor R3 is thermally coupled to a power amplifier A in a monolithic IC chip, and the base of Q12 is biased at a cutoff potential under normal operating conditions. When the temperature rises to a first predetermined level V.sub.BE of Q12 drops below its biasing potential owing to the temperature characteristic of Q12, whereby Q12 conducts, which cuts off Q13 and, through transistor Q14, disables the amplifier. The common emitter feedback provides a thermal hysteresis characteristic, whereby Q12 is not cut off again until the temperature drops below a second predetermined level.