Abstract: Circuit arrangement using carrier frequency control voltage on low voltage power lines for radio interference suppression in brightness control devices using the phase gating principle, comprising a radio frequency interference filter including an interference suppression choke coil and wherein a semiconductor switch combined with the interference suppression choke coil is connected in series with the load circuit which includes at least one incandescent lamp and wherein a capacitor is shunted in parallel with the series-connection of the interference suppression choke and the semiconductor component, including a further choke in the load circuit which presents a high impedance to the carrier-frequency control voltage, thereby preventing the loading of the control voltage on the power lines caused by the low impedance of the capacitor at the carrier frequency when the semiconductor component is in the non-conducting state.