Signal transmission method and related device

The invention relates to a signal transmission method and a related device. An electrical power supply device (10) for an LED light source has a primary side (12) and a secondary side (14) is provided. An optical coupler (18) is arranged between the primary side (12) and the secondary side (14) and is suitable for transmitting a wide band control signal and a numerical information signal. The control signal and the information signal are transmitted on a rectangular wave signal modulated in combination with frequency modulation and pulse width modulation or PWM modulation (42), the control signal and the information signal are modulation signals for frequency modulation and pulse width modulation. A signal adjusting circuit (44) including a current mirror is coupled to an output of the optical coupler (18) so as to allow the rapid transmission of the modulated signals without the need for special high-speed assemblies.