Abstract: A hot air furnace which includes at least one heat exchange unit having at least one mounting flange section defining an opening therein and a plate member having an aperture therein corresponding to at least one of the openings in said heat exchange unit and in alignment therewith with sheet insulating material interposed between said plate member and heat exchange unit by virtue of the said flange being expanded into a plane parallel to that of said plate member to thereby secure the plate member and interposed insulating material in place on said heat exchange unit.

Abstract: A contact-free electrical pulse generator, that utilizes a Hall effect device and a permanent magnet to generate lines of flux and provides two stable output states when cooperating with a flux conducting cam having a stepped peripheral circumference mounted on a rotating shaft is disclosed. The flux conducting cam enhances the flux density imposed upon the Hall effect device when the high portion of the cam becomes proximate the Hall device. The concentrated flux lines flowing through the Hall device changes the state of the device in accordance with the preselected angular positions of the rotary shaft.