Low-level inversions over the tropical Pacific

1,113,397. Supply systems for gas discharge lamps. GENERAL ELECTRIC CO. 26 April, 1966 [24 May, 1965], No. 18136/66. Heading H2H. [Also in Division G3] A load 1, e.g. a gaseous discharge lamp, is supplied from an A.C. source 2 by way of backto-back thyristors 7, 8 which receive firing , pulses from a circuit 23 comprising an adjustable resistor 10 connected in series with a capacitor 11, a glow lamp 12 connected across the capacitor 11 and a pulse transformer 9, a current-dependent voltage derived from a reactor 6 in series with the load being applied to the circuit 23 by way of an integrating circuit 18, 19; when glow lamp 12 becomes conductive as a result of voltage build-up on capacitor 11, the capacitor partially discharges and a firing pulse, of a particular duration and at a particular time in the half-cycle, is applied to the thyristors 7, 8, the appropriate one of which fires to supply current to the load. Thus, the power supplied to the load is controlled in dependence upon current variations, by automatic regulation of the firing angle of thyristors 7 and 8. A further current-dependent feedback voltage derived from reactor 6 is applied to a lamp 30 associated with a photosensitive device 15 connected to the circuit 23, and this feedback also helps to stabilize the load current. The lamp associated with the device 15 may be itself responsive to a further photo-sensitive device responsive to variations in the light output of a discharge lamp constituting the load 1 so that the firing angle of the thyristors 7, 8 is controlled to keep the light output at a constant value (Fig. 3, not shown). And an embodiment featuring compensation for varying input voltage and a photo-electric circuit for automatically turning the lamp on and off at a desired ambient light level is described with reference to Fig. 4 (not shown).