AC stabilizer for mains powered electrical equipment
M G Stanton · Journal of Physics E Scientific Instruments · 1972
This stabilizer was designed to meet the following requirements. Firstly, it is compact enough to be included within individual pieces of electronic equipment. Secondly, it is constructed with readily available electronic components and requires no special transformer. Thirdly, its output waveform is closer to sinusoidal than some types of constant voltage transformer. Worst case distortion figures measured were 2% of second harmonic and 7% of third harmonic. The device incorporates a negative feedback loop between a threshold detector and control system via an opto-electronic link. Control ratio is between 5 and 10 over the range 200-240 V input.