Appliances such as fluorescent lamps and low-voltage DC motors can be operated from household AC without a transformer by employing a current-limiting circuit which is compact, lightweight, reliable, draws less energy, and has fewer power consuming components than do prior devices for driving those applicances. The current-limiting circuit has 4 rectifiers in a bridge circuit and a current-limiting capacitor which should be selected to match the load, a larger capacitor being necessary to supply a larger current. When used to drive a discharge lamp, the current-limiting circuit should also contain an inductive coil in series with the current-limiting capacitor. Otherwise there may be undue flicker. The inductive coil and capacitor together improve the power factor and therefore reduce the current drawn from the line without reducing the lamp output.

The present application discloses a circuit for improving the efficiency of energy consumption, extending lamp life, and facilitating the starting and steady state flickerless operation of a discharge lamp normally utilizing a source of alternating current, such circuit including: (a) a full wave rectifier connected between both an input set of terminals and an output set of terminals, the input set comprising the AC line input leads and the output set comprising the positive and negative supply leads of the lamp; (b) a voltage-raising capacitance disposed between one terminal of the AC input and one or both terminals of the rectifier output; and (c) a filtering means connected between the positive and negative output of said full wave rectifier, wherein the output of the voltage-raising capacitance is applied across the filtering means, thereby providing a no-load voltage at the output leads which is approximately equal to (2.sqroot.2) .sup.E input (rms). Additionally, in order to prevent excessive charge buildup within the lamp; provide equal wear of each lamp electrode; and, to minimize migration of the phosphor coating of the lamp, a switching means is provided in order to approximately equalize the amount of time during which the lamp current flows in each direction through the lamp.

A fluorescent lamp ballasting means comprises a conventional voltage doubler, which voltage doubler is adapted to operate from a regular power line AC input voltage and to supply a unidirectional output current to the fluorescent lamp. After the lamp has been started, the resulting lamp current is determined in part by the size of the capacitors used in the voltage doubler and in part by the impedance of an impedance means connected in series between the lamp and the voltage doubler. By choosing the magnitude of the voltage doubler capacitors such as to constitute the major lamp-current-determining factor, a relatively good overall systems efficacy is obtained. Lamp starting is aided by capacitively coupling the input AC voltage to the lamp in a fashion additive to the DC voltage provided by the voltage doubler--this DC voltage being coupled to the lamp by way of a rectifying means. As a result, the peak lamp starting voltage is equal to four times the peak voltage of the input AC voltage. Yet, by accomplishing the coupling of the AC voltage to the DC voltage by way of one of the lamp's pairs of terminal pins, the coupling only occurs when the lamp is present in its sockets; which implies that the open circuit socket voltages are maintained at relatively low and safe levels. Additional lamp starting aid is provided by establishing an AC voltage field between the fluorescent lamp and a starting aid electrode placed in close proximity to the lamp.

Apparatus for cooling a metal extrusion, such as an aluminum extrusion, may include a carriage which houses the cooling liquid delivery system and is relatively movable with respect to the extrusion press in order to provide the desired amount of air cooling prior to quenching. The quenching apparatus may have a plurality of generally parallel cooling liquid delivery tubes, each having a plurality of nozzles which are preferably independently adjustable as to volume and spray pattern. The cooling liquid delivery tubes may be axially rotated and flow of the cooling liquid within each tube may be independently adjusted. The housing of the quenching unit may have an upper portion which is rotatable generally upwardly and is provided with a transparent window to facilitate viewing of the spraying action. A method of quenching an aluminum extrusion employing such apparatus is provided.

A low-pressure mercury vapor discharge lamp in which a rare gas and mercury are provided in an outer bulb, which in turn contains therein a plurality of bent inner tubes, each having an opening at an end and an electrode at the other end thereof. A starting probe is provided between the openings in the outer bulb. An operating circuit or starter is connected to the electrodes. Further, a starting probe circuit is connected to the starting probe to apply a high voltage to the starting probe at the time of ignition.