Abstract: A device for regulating delivery of power from an AC voltage source to a load such as a lamp, a motor, a heating element or the like is described. Electronic circuitry responsive to the AC voltage generates a periodic signal whose magnitude indicates the instantaneous phase angle of the AC voltage relative to the most recent zero crossover of the AC voltage throughout the entirety of each half cycle of operation. A comparator generates a triggering signal when the phase angle signal corresponds to a threshold signal which may be manually set by adjustment of a voltage divider or which may be generated by a sensor in response to a predetermined condition, such as ambient light level or temperature, which is to be regulated by appropriate delivery of power to the load. The triggering signal is applied to a triac series connected with the load to initiate conduction of load current.

Abstract: An electric heater employs plate-shaped heating elements, each consisting of a core of semiconductor material whose opposing faces are coated with conductive material and having a multiplicity of apertures to permit passage of air. The heater includes a housing with a rear air inlet and a forward air outlet. A fan having a fan venturi causes air flows forwardly through the housing. A two-piece, ceramic holder maintains a number of the plate-shaped heating elements in generally coplanar, spaced-apart relationship, in front of a forward venturi opening. The holder has a large recess positioned over the forward venturi opening which receives substantially all air flow from the venturi, and a number of passages, one associated with each heating element, which direct air from the recess through the cores towards the forward air outlet.