Abstract: An optical element providing greater conversion efficiency and comprising a pyramid having a square base and four triangular faces of equal size and shape meeting at the apex. The optical element can also comprise an octahedron or double pyramid of similar configuration.

Abstract: An anti-theft device for vehicles comprising a control circuit between the positive pole of the vehicle battery and the battery terminal of the solenoid of the starter. The control circuit comprises an SCR whose anode is connected to the positive pole and its cathode connected to the battery terminal of the solenoid. The control circuit is normally open and when closed by a detachable circuit key permits the battery positive pole to be now connected to the battery terminal.

Abstract: A transformerless battery charger having a circuit for connecting the battery to an A.C. power source to supply charging current to the battery including: an inductive impedance in series with the battery for limiting the charging current through the battery. An electronic switch in the form of a TRIAC or SCR is connected in series with the battery, and the electronic switch is normally non-conductive thereby keeping open the charging circuit for the battery. An electronic trigger for turning on said electronic switch is provided to close the charging circuit for the battery as a function of the difference between the instantaneous voltage from said A.C. power source and the battery voltage. The electronic switch and the electronic trigger jointly operating to provide a pulsed charging current to the battery during the A.C. power cycle which is long enough to produce a significant battery-charging effect but short enough to avoid harmful internal heating of the battery.