Filtering device is intended in particular to the electrical installations for transmitting messages by the carrier frequency in the telephone networks

摘要

514,074. Distributing music etc; impedance networks. LORENZ AKT.-GES., C. Oct. 14, 1938, No. 29841. Convention date, Oct. 19, 1937. [Class 40 (iv)] [Also in Group XL] In a composite high and low pass filter particularly for use in systems for distributing radio-frequency programmes over the telephone network, the high pass filter comprises a transformer with one or more condensers in series with one or both windings. In the arrangement' shown in the Figure, a telephone line A, B is connected over a low pass filter 2 to a telephone subscriber's set 4 and over a high pass filter 1 to a radio frequency receiver 3. The high pass filter comprises a transformer 16 having split windings with interposed condensers 17, 18. In modifications, condensers may be connected at each end of both windings, at one end of each winding or at one end of the primary winding only, the capacity to ground of the condenser or condensers in the asymmetrical arrangements being compensated by the capacity to ground of the winding or windings of the transformer.