GB148586A - Improvements in or relating to signalling apparatus - Google Patents

Abstract

148,586. Oulianine, S. Jan. 29, 1919. Receiving and detecting audible signals; sound, controlling and actuating apparatus by.-A tone filter or selective device responding to predetermined frequency of vibration, applicable to signalling or other apparatus, in which it is desired to pick out some particular frequency from a number of other frequencies received, comprises a tunable resonator such as a reed or stretched string resiliently connected to a vibrating member which responds to various frequencies. As described, a stretched string E tuned to desired pitch by a peg F and movable bridge G passes through an elongated hole in a plate spring C carried by, and giving a resilient connexion with, a vibrating member B which is shown as a flexible member forming the armature of an electro-magnet A, the coils of which receive current from, for example, a wireless aerial. The bridge G allows adjustment so that the resilient connexion C is not situated at a node. The string gives an audible note when impulses of predetermined frequency are received. In a modification, a microphone actuated by the string or vibrating member serves to transmit the impulses to a telephone receiver. In a further modification, Fig. 5, the member C is elongated to engage with a wheel P so that receipt of predetermined vibration-frequency steps round the fly O of a circuit closing device or relay of the kind described in Specification 110,569, [Class 35, Electric switches &c.], to actuate any desired signalling or other apparatus. According to the Provisional Specification, the connexion between the resonator and vibrating member may be non- mechanical. For example, the " string " may be a wire carrying electric current, or supporting a piece of iron, and caused to vibrate by variations in the field of the magnet. Also, two bridges may be provided for adjustment purposes.