Electronic device for controlling the brightness of an electric gas-discharge lamp without an incandescent cathode

Abstract From the Canadian patent

For the purpose of controlling the electrical energy fed to an electrical gas discharge lamp without an, incandescent cathode, as a function of a d.c. control voltage there is provided a circuit arrangement by means of which the ignition timing or angle of a triac may be varied within each alternating-voltage half-wave. In order to prevent the lamp from unwanted extinction when adjusted to minimal brightness an additional circuit arrangement is provided ensuring a, given minimal intensity of the current flowing through the said lamp, regardless of the level of the said d.c. control voltage. The additional circuit arrangement comprises a current transformer and a rectifier arrangement for …