About: http://webisa.webdatacommons.org/408595063

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	Such frequencies are determined by the expression f,/(6n+1) where f is the frequency of the supply voltage and n is a positive integer.
http://www.w3.org/ns/prov#wasQuotedFrom	freepatentsonline.com