Abstract: Current regulator circuits using electrical feedback to stabilize the bias currents of semiconductor laser diodes are disclosed. In these electrical feedback circuits laser diode current is sensed with negative-temperature-coefficient resistance to develop voltages which are compared to zero-temperature-coefficient voltages for generating error signals, and these error signals regulate the emission from the laser diode against changes with temperature.

Abstract: A panel assembly for the in-situ production of a standing seam roof has panels which, at one end, have a vertically standing hook formed atop a semi-trapezoidal fold, while at an opposite end, a vertically standing hook is formed atop and is part of a substantially trapezoidal fold. The first hook is designed to be simply and securely retained within the second hook through the use of a camming interlocking action and the free edge of the second end is upwardly bent so as to rest against the semi-trapezoidal fold of a like panel joined to said end to form a series of interconnected panels that are mounted to roof purlins by fasteners hidden by the standing seam. In a roof requiring plural parallel series of panels, upper and lower clamping bars are provided to form a tight, leak-proof lap joint between the adjacent panel series in a manner avoiding the need for the use of exposed fasteners which must extend through exposed roof portions.