Electroacoustical converter characteristics measurement - has especially shaped carbon microphone to give contact to pins mounted in test assembly

摘要

The unit is to measure the transfer characteristics of an electro-acoustical convertor in the form of a carbon microphone for a telephone. The test sample must be partially circular, interchangeable and give contact to the receiving unit (1, 3). This unit has at least three spring loaded pin shaped contact elements (5) mounted on a circle axially central to the sample which make contact with ball shaped protrusions which are on the sample. The unit includes a rotatable stand assembly (13) in line with the sample axis held with the fixing ring (12). The stand has a cylindrical outer surface (10) and the ring a mating inner surface (11) to give the bearing effect. Contact to the stand from the pins (5) is provided by the spring loaded pins (18, 19) together with the slip rings (16, 17).