GB362639A - Improvement in condenser telephone transmitter apparatus - Google Patents

Abstract

362,639. Sets. DEHN, F. B., 103, Kingsway, London.-(Jenkins & Adair, Inc. ; 3333, Belmont Avenue, Chicago, U.S.A.) Nov. 17, 1930, No. 34586. [Class 40 (iv).] Relates to telephone transmitter apparatus, more particularly for broadcasting and phonographic recording purposes, of the type in which a housing adapted to have a condenser type transmitter supported thereon is detachably associated with a supporting frame for an amplifier and consists in so arranging the parts that the amplifier can be disassembled without disturbing the position of the transmitter. In the construction shown, an amplifier unit 8 is mounted in a readily detachable manner on sponge rubber &c. pads 16 in a casing 2, the front of which is provided with arms 18 and screws 20 adapted to support resilient non-metallic members 22 which are connected to eye hooks 24 on the split clamping ring 26 which receives the condenser microphone 28. A non-metallic resilient member 30, Fig. 1, extending between adjacent hooks 24 holds the halves of the ring 26 together. The microphone is electrically connected to the amplifier by a plug 40 and conductor 38 whilst the plug 34 of a ground wire 36 engages a socket 32 in the lower portion of ring 26, the other end of wire 36 being connected to terminal 42 on the frame 8 which is earthed through a resilient contact finger 66 engaging the casing 2. The amplifier terminal supporting bar 12 is adapted to receive battery conductors 46, 48, 50 and output conductors 52, 54, the latter being shielded from the former by a metallic sheathing 56, Fig. 7, whilst another metallic sheathing 58 with an outer insulating fabric covering 60 surrounds the entire group of conductors. An extended portion of sheathing 56, Fig. 3, is connected to earth terminal 42 and the cable 44 passes through an insulating collar 62 having a sliding fit in a groove in the lower wall of casing 2 so as to be readily removable after the rear cover 4 of the casing has been removed. The front of the casing is provided with projections 76 adapted to be clamped in eye hooks 74 on a ring member 72 carried by the upright stem 70 of a microphone stand 68. Feet 80 are also provided on the casing to enable the device to be placed on a flat surface such as a desk or table.