For the bridge rectifier shown the desired output voltage is

For the bridge rectifier shown, the desired output voltage is 5V (DC). The input AC voltage (Vi,nc) is 120V(rms). Assume the diode voltage drop is 0.7V. Calculate the required transformer winding ratio.

Solution

Out put voltage of bridge rectifier = 2Vm/ = 5

Vm= 5x / 2

= 7.85v

R.m.s voltage. = V r.m.s =Vm/1.414

= 5.55 V

Secondary voltage of transformer = 5.55+(2x0.7)

= 6.95 V

Transformer winding ratio = a = V1/V2

= 120 / 6.95

= 17.3

Turns ratio. = n1/n2. = 17.3. : 1