that is represented by a resistor 9 the capacitor 5 is charged by current i 3 which is provided from the switching mode power supply 7 rather than directly from the input current i 1 having a direction represented by arrow 13 hence the term bootstrapped is applied to this ac dc converter in fig4 to which reference should now be made i 3 is represented by curve 20 and i 1 is represented by curve 19 the input voltage v i is represented by curve 12 and the rectified voltage v 1 is represented by curve 15 during the first time period as indicated by the dimension lines 24 the capacitor 5 is charged to maintain the v 3 voltage level that is represented by curve 22 during the second time period 26 the capacitor 5 is discharged while maintaining a base threshold voltage v 3 that is above the zero voltage line as indicated at point 21 the charge is taken away at this time through the gating diode 23 and ensures that the input current i 1 as represented by curve 19 does not approach an inordinately high level the first time period is defined by equation 1 by the table of equations while the second time period is defined by equation 2 equation 3 relates i 3.