Abstract: A low voltage two wire dimming circuit comprises a voltage compensating circuit for regulating the RMS value of an AC voltage applied to a load and a correcting circuit for eliminating damaging DC current that may flow through the load. The voltage compensating circuit adjusts the firing angle of an electronic switch disposed in the dimming circuit to compensate for fluctuations in the AC supply voltage. The correcting circuit advances or retards the firing angle during selected half cycles to correct for asymmetries in the AC load voltage waveform caused by excessive DC current. According to the invention, there is also provided a two wire low voltage dimming circuit without voltage compensation but having improved dimming ability at low load currents and improved resistance to the flow of damaging DC currents.

Abstract: A low voltage two wire dimming circuit comprises voltage compensating means for regulating the RMS value of an AC voltage applied to a load and correcting means for eliminating damaging DC current that may flow through the load. The voltage compensating means adjusts the firing angle of electronic switch means disposed in the dimming circuit to compensate for fluctuations in the AC supply voltage. The correcting means advances or retards the firing angle during selected half cycles to correct for asymmetries in the AC load voltage waveform caused by excessive DC current. According to the invention, there is also provided a two wire low voltage dimming circuit without voltage compensating means but having improved dimming ability at low load currents and improved resistance to the flow of damaging DC currents.