Abstract: The switching power supply has pulse width modulation controller 51 isolated by transformer 35, which is connected by line 33 to the output, VO, across lines 27 and 29. An alternating input is obtained from transistor 19 acting as a switch controlled by alternating signals on line 15 connected to node C. Diode 37 in series with resistor 39 provides damping. Response is very fast and effective, and the input elements, including controller 51, are fully isolated.

Abstract: A keyboard assembly (FIG. 1, 11) is constructed of first light transmission members (13) second light transmission members (15), a key actuation assembly (17) having a matrix of keybuttons (25), plural light source assembly (19) and plural sensor assembly (21). Each light source on assembly (19) is exclusively and sequentially energized causing its light to be transmitted through the first light transmission member (13) to be split up and deflected downwardly by the surfaces (43) and then rightwardly by the surfaces (45) to emanate through the surfaces (47) to enter the surfaces (49) of the second light transmission member. Actuation of a keybutton (25) causes its associated interrupter (29) to assume a light blocking position between the first light transmission member (13) and a second light transmission member (15). Light passing through the second light transmission member (15) to the sensor array indicates that none of the interrupters (29) have blocked the light path.