GB792916A - Improvements in electrical equipment for producing flashing lights - Google Patents

Abstract

792,916. Supply systems for consuming devices. PARMEKO, Ltd. Feb. 8, 1956 [Feb. 24, 1955], No. 5564/55. Class 38 (4). A system for producing flashing lights comprises a saturable reactor having two iron cores 1 each wound with A.C. windings 2, which are in parallel opposition, and D.C. control windings 3 which are connected in series aiding relationship. The A.C. windings 2 are in series with a capacitor 8 and load 9 which may be represented by a number of lamps, or an apparatus from which the lamps are operated. A variable resistor 7 is adjusted so that the A.C. circuit becomes resonant, whereupon the current therein rises, thereby altering the impedance of the A.C. windings and so causing the circuit to fall out of resonance. As a result, the alternating-current now decreases until the circuit is resonant again, this cycle being regularly repeated to produce the emission of pulsating light. The variable inductance is also parallel resonated by means of a second capacitor 10 for increasing the range of the variation of alternating-current, so that the lamps may actually be extinguished at each fall in the current. The A.C. and D.C. supplies to the saturable reactor may be derived from separate secondary windings of a common transformer, the windings 3 being connected to a bridge rectifier. A second bridge rectifier may be used for converting the A.C. at the output side of the capacitor 8 into D.C., and a potentiometer may be provided for adjusting the rate of pulsation of the illumination afforded by the load 9, Fig. 2 (not shown). The lamps may then be supplied through a magnetic amplifier having, as its first stage, an auto-excited transductor with a potentiometer for further control of the degree of brilliancy. In its second stage, the amplifier incorporates a saturable reactor together with a switch which enables a static warning light to be given although the pulsating system may be out of operation.