Ngowe-1895, i-Overtone yaseJamani yavelisa eyeyokuqala ehlabathiniI-DC drill yombane.Iqokobhe lenziwe ngentsimbi etyhidiweyo kwaye liyakwazi ukugrumba imingxuma eyi-4mm kwipleyiti yentsimbi.Emva koko, i-drill yombane yamanqanaba amathathu (50Hz) yavela, kodwa isantya semoto asiphumelelanga ukudlula i-3000r / min.Ngomnyaka we-1914, izixhobo zombane eziqhutywe yi-motor-single-phase series motors zavela, kwaye isantya semoto safikelela ngaphezu kwe-10000r / min.Ngomnyaka we-1927, isixhobo sombane esiphakathi kunye ne-frequency supply frequency ye-150 ukuya kwi-200 Hz yavela.Ayinayo nje inzuzo yesantya esiphezulu senqanaba elinye lemoto, kodwa ikwanezinto eziluncedo ezilula nezithembekileyo zenqanaba lesithathu lemoto frequency.Nangona kunjalo, kufuneka ibonelelwe nge-intermediate frequency current., Ukusetyenziswa kuthintelwe.