A safety device for an elevator which has a converter for converting a 3-phase A.C. power source into a D.C. power source, a control circuit for the elevator employing as a power source the D.C. power source outputted from the converter, a level converter for converting the voltage of the D.C. power...http://www.google.es/patents/US4944369?utm_source=gb-gplus-sharePatente US4944369 - Safety device for elevator
