There 12v step down transformer is used and opamps are use .. This can be found in LM324 IC . Found the data sheet and use it.
3 phase supply can b use to drive bldc circuits which are found in HDD..
Therr the valu of resustance ( shown 5.6k) is calculated according to this formula
R=(1.732*10^6)/(6.38*freq*Capacitance)
Freq- used as input
Capacitance used in circuit
( best 1kh to 400hz -> 100nf
400-50hz -> 1000nf )
