PURPOSE: To energize a slide plate backward invariably and to eliminate the play between the slide plate and the slide lever of a variable resistor by equipping the slide lever with a spring for energizing the slide plate.

CONSTITUTION: When an electrical circuit part B is incorporated in a push- button type tuner A, the circuit part B is arranged in front of the push-button type tuner A so that the slide lever 43 of the variable resistor 41 slides, the slide plate 53 and slide lever 43 are coupled together by a pulley 44 and a wire 45 so that the slide lever 43 projects in the forward movement direction of the slide plate 35, and a spring 46 operating on the slide lever 43 is provided instead of a spring which energizes the slide plate 35. Then, the spring 46 tows the slide 434 as shown by an arrow and also energizes the slide plate 35 backward through the wire 45, and a channel selection dowel which moves forth together with a channel selection member collides with the slide plate 35 to make a channel selection.