Patent attributes
An emulation circuit is disclosed for connection to a low energy lamp energized by an AC supply and substituted for an incandescent lamp in a traffic signal installation. The circuit comprises means for sensing the magnitude of a supply voltage applied to energize the lamp connected to the terminals and means for sensing correct operation of the lamp. When the lamp is sensed to be operating correctly an auxiliary load intermittently to draw an additional current through the auxiliary load from the AC supply. The additional current is drawn only between preset phase angles of the cycles of the AC supply and the magnitude of the additional current drawn by the auxiliary load is varied in dependence upon the sensed magnitude of the supply voltage.
