low power transformer for high current output

[electrophile]

Hi, i'm designing a dual output power supply with each capable of 2A. For such a scenario the input needed is 24V and with dual 2A output my transformer will need to be in the 125VA to 150VA range which are really expensive. Is there a way i can use a low current transformer add a bridge rectifier and multiply the current this bridge outputs?

 

[schmitt trigger]

(Volts *Amps)/ Efficiency * 2 = Total watts
Assuming an efficiency between 0.8 and 0.9, you require between 107 and 120 watts. This is assuming a relatively simple switchmode regulator, if you use a linear regulator the efficiency could drop below 0.5

Since a rectified sinewave lowers the power factor, a bare minimum 150VA transformer is required.