Northern Telecom Limited

Eric Foster

Beverley W Gumb

Alan C Busche

Laurence J Retallack

William D Greason

A modular jack for a telephone, particularly for use in a handset, has a minimal height or profile by using a circuit board, on which the jack is mounted, as one of the walls defining the aperture into which a modular plug is inserted. The overall height of the jack is reduced by the thickness of the circuit board. The jack and board assembly has the smallest height dimension possible.

Low profile circuit board mounted telephone jack

A telephone transmitter including an electret transducer is connected to an electrical circuit mounted in the transmitter housing. A resistor which can be of varying value is also connected to the circuit, the value of the resistor being adjusted to bring the operating characteristics within predetermined values. This is done by applying a sound signal of known frequency to the transducer and measuring the output characteristics of the transducer. This enables the suitable value of resistor to be connected into the circuit. By this means variations arising from varying atmospheric conditions at assembly, and other causes, can be allowed for. The metallized strip or film of the electret is preferably mounted with a very slight Vee shaped formation to avoid tight manufacturing tolerances which occur with a straight, or flat, strip.

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London, Canada

Eric Foster