GB953429A - Control means for flashing electric lamp systems - Google Patents

Abstract

953,429. Semi-conductor pulse-generating Circuits. ROTAX Ltd. March 10, 1961 [April 29, 1960], No. 15075/60. Heading H3T. A semi-conductor pulse-generating circuit for causing two lamps 5, 5a to flash alternately with a delay between the switching off of one lamp and the illumination of the other comprises transistors 7, 7a which are rendered alternately conductive by means of a multivibrator circuit comprising transistors 21, 21a, conduction of one transistor, e.g. transistor 7, resulting in a rising voltage being produced across capacitor 10, the rising voltage, after a delay, causing the breakdown of double-base diode 11 and the production across resistor 12 of a voltage which triggers silicon control rectifier 6 and so permits current to flow through lamp 5. Lamp 5a is similarly switched on after a delay with the switching on of transistor 7a, this latter switching coinciding in time with the switching off of transistor 7 and lamp 5. In a modified circuit in which the transistors are of NPN type and the polarity of the supply is reversed, Fig. 2 (not shown), the rectifiers 6, 6a and double-base diodes 11, 11a are also reversed in polarity, the latter being connected between the collectors of transistors 7, 7a and supply terminal 1, and the order in which the resistors 9, 9a and capacitors 10, 10a are connected between these points being reversed.