Abstract: In an electronic musical instrument, an expression control circuit constituted by a first variable resistor is connected in the path of the tone signal. A second variable resistor is connected in series with or in parallel to the first. A third variable resistor is connected in shunt between the output side of the expression control circuit and the ground. The second and the third variable resistors can adjust the variation range of the tone signal at the output of the first variable resistance.

Abstract: A variable-resistance attenuator having first and second resistive layers deposited upon an insulating substrate. Input and output terminals are electrically connected at spaced intervals to one of the resistive layers and a common terminal is electrically connected to the remaining one of the resistive layers. A pair of contacts are adapted to make slidable electrical engagement, each with an associated one of the resistive layers. Conductive bridging means mechanically and electrically connect the sliding contacts. Mechanical means are provided for simultaneous movement of the sliding contacts to change the resistance in a smooth and continuous fashion.

Abstract: A trimming potentiometer in which three parallel resistance paths are located in a plane on an insulating plate. Wiper contacts are displaceable in the same direction on the resistance paths, and are attached to a common carrier which is longitudinally displaceable by a threaded spindle. Inductance loops are arranged between the resistance paths and the respective terminals for the paths, for the purpose of matching the trimming potentiometer to its inductance and capacitive input and output values.

Abstract: A broad band directional coupler including a conventional attenuator is disclosed. The coupler permits detection of signals propagating simultaneously in opposite directions on a single-signal path or transmission line. Detection may occur at one or a multiplicity of ports located at arbitrary positions along the line. In the specific embodiments disclosed, the attenuators employed are symmetrical, .pi., O, T, and H attenuator networks. The invention, however, is equally applicable to .pi., O, T or H attenuator networks which are not symmetrical. The specific embodiments shown employing active devices have wide frequency responses which are flat and flat to DC. Where operation down to DC is not required and where a broad band directional coupler comprised entirely of passive elements is desired, a version of the coupler circuit employing transformers is disclosed.