| 摘要 |
PURPOSE:To control a device to be controlled accurately by constituting the smoothing circuit of a demodulating section of a variable resistance and a capacitor and setting the value of resistance according to control signal frequency and thereby obtaining fixed demodulated output. CONSTITUTION:A control signal from a power line L is applied to a filter section 2 through a coupler 1, and amplitude modulated waves modulated by frequency lower than frequency characteristic of the filter 2 are passed. Output of the filter 2 is applied to a demodulating section 4 through an amplifier 3 to demodulate the amplitude modulated waves. Amplitude modulated waves from the input transformer T of the demodulating section 4 are rectified by diodes D1, D2 and inputted to a smoothing circuit that smoothness the demodulated signal. The smoothing circuit is made up of a variable resistance R and a capacitor C, and the value of the variable resistance R is set according to frequency of the control signal. Fixed demodulated output is applied to a judging section 5 for each control signal, and a device to be controlled is controlled accurately by a driving section 6. |
