Microphone circuit control mechanism for breathing apparatus

Abstract

A microphone circuit control mechanism which is utilized to control the output of a microphone (20) disposed in a breathing mask (12) the microphone circuit extending to a communications device (22) and wherein the microphone circuit control mechanism includes a switch (86) in the microphone circuit, which switch can be toggled between "on" and "off" states in response to a drop in pressure within a pressure sensing chamber (44). The switch (86) is a single-pole double-throw magnetic reed switch which is disposed within the pressure sensing cavity (44), which cavity is in a demand regulator (14). The regulator includes a valve (27) capable of admitting air under pressure into the pressure sensing chamber when required. The magnetic reed switch (86) is toggled in response to movement of a magnet (112) carried by a portion (64) of a valve operating means (30) which portion moves in response to a drop in pressure in the sensing chamber (44). The reed switch (86) includes a pigtail (100 ) which has been configured and positioned in such a manner relative to the permanent magnet as to provide an adjusting structure for adjusting the toggle position.