GB319715A - Improvements in or relating to sound reproducing systems and apparatus therefor - Google Patents

Abstract

319,715. Tomlins, F. C. June 27, 1928. Electric circuit arrangements.-In the reproduction of sounds from gramophone records or talking pictures, continuous reproduction from a number of record carriers is obtained without sudden change by automatically causing the volume of sound from the end portion of one record to decrease gradually whilst the volume of sound from the commencement of the next record is gradually increased. In the arrangement shown, the tracking arm 3 of an electrical pick-up 1 when nearing the end of one record closes a switch 9 to operate a relay 11 and energize a stepping- magnet 13 to rotate a wheel 15 connected to a fader-switch arm 18. This switch arm controls a network of resistances R connected at the end 22 to the pick-up 1 the output from which is to be diminished, and at the end 23 to the pick-up 2 the output from which is to be increased. The contact strips 28, 29 of the fader-switch are connected through transformer 30, valve-amplifier 31, and transformer 32 to a loud-speaker 34 and the movement of the switch arm over contacts x, y, causes a progressive increase in the resistance in the circuit of the pick-up 1 and a progressive decrease in the resistance in the circuit of the pick-up 2. When the movement of the switcharm in one direction is complete, an arm 21 on the wheel 15 opens a switch 19 to stop the stepping-magnet 13. The arm 4 of the pick-up 2 acts in a similar way to energize a stepping-magnet 14 to reverse the movement of the fader-switch when the pick-up 2 nears the end of its travel. A modification is described in which the faderswitch is operated by an arm which rotates in one direction only.