According to the present invention, there are provided an input terminal, an output terminal, an a.c. generating circuit and a voltage-anomaly detecting circuit. Power supplied to the input terminal is outputted from the output terminal based on an output produced from the voltage-anomaly detecting circuit....http://www.google.se/patents/US5998886?utm_source=gb-gplus-sharePatent US5998886 - Power supply apparatus having a function of compensating for changes in voltage
