2. Search for the number of coils: The primary coil n1=220╳9.8=2156 ╳ coil n2=8╳9.8 1.05=82.32 ╳9.8╳1.05=82.32 The number of turns of the secondary coil is the number of turns for considering the pressure drop under load.
3, the input capacity of the transformer, the output of 8 volts of current setting method: here I assume 2 amps. Output capacity of the transformer =8╳2=16 volt ampere, input capacity of the transformer = output capacity of the transformer \/0.8=20 volt ampere, primary coil current I1=20\/220=0.09 ampere.