Abstract: Recording machine such as electrostatic printer/plotter or facsimile plotter includes housing construction and associated operating components whereby overall external width reduction is accomplished without loss of function using liftable lid and method of cross-bracing. Machine serviceable through removable bottom closure panel supporting an electronic chassis. Operating stations, such as recording assembly including both electrostatic latent image recording station and a toner developing station, and web-cutting assembly each includes portions in both lid and base of housing to be yieldingly held together in cooperating relation by hinged latching panel in which the hinge pin supplies spring action to urge and retain the latching panel in its detented position.

Abstract: In a double beam spectrophotometer employing a rotating optical chopper to direct a beam of electromagnetic radiation alternately through sample and reference channels to a photomultiplier tube, a beam interrupter is used in combination with a photodiode and a photocell to generate a square wave signal having a predetermined temporal relation to the rotation of the optical chopper. The square wave signal is integrated to provide a triangular waveform, whose maxima and minima correspond, respectively, to the passage of the beam through one or the other of the sample and reference channels, and whose cross-over points with respect to a zero reference level correspond to dark intervals during which the beam is blocked from entering either channel.