The transformer may function at {HEAD ~ any desired frequency}, from very low frequencies through {TAIL ~ power frequencies} and audio frequencies to very high frequencies 
The transformer may function at { HEAD ~ any desired frequency } , from very low frequencies through { TAIL ~ power frequencies } and audio frequencies to very high frequencies
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH