11-11-2012, 07:02 PM
That is the arrangement for every switched-mode PSU that has a voltage selection switch. Instead of one smoothing capacitor, there are two. For 230Vin operation, they are in series, but when the 115V switch is operated, neutral is connected to the junction of the two capacitors. Of the diode bridge, two diodes become non-operational, and the other two form the voltage doubler in conjunction with the capacitors. Very neat. Additional capacitors aren't needed.
Of course, modern power supplies with active power factor correction use a boost converter ahead of the main smoothing capacitor, and this performs the function of automatic voltage selection while making the current draw look somewhat sinusoidal. Also very neat.
In short, power supply design is fascinating
Of course, modern power supplies with active power factor correction use a boost converter ahead of the main smoothing capacitor, and this performs the function of automatic voltage selection while making the current draw look somewhat sinusoidal. Also very neat.
In short, power supply design is fascinating
