Abstract: A hand held actuator comprises a truncated conical housing wherein the volume of air is pressurized by flexure of a diaphragm. A rib protruding from an outer peripheral margin of the diaphragm is received in a groove of a support plate unwanted flexure of the peripheral margin is obtained by supporting the edges of the diaphragm and the plate in spaced apart grooves formed in the interior wall of the housing. The volume of air pressurized by the operation of the diaphragm is communicated by a duct to a signal switch. In one embodiment the duct is connected in a fluid type manner to the interior of the housing by the tapered sleeve. In another embodiment, the duct is joined to a tube forming an extension in an opening in the support plate forming a diaphragm.