What is the max dc voltagee to be obtained from a transformer with an 18 v rms secondary using a bridge rectifier ckt with a filter?

Answer 1

About 24 volts. Take 18 and divide by 0.707, then subtract about 1.4 to compensate for the two diodes that will always be in series with the load.

Of course, any load will cause ripple, so the 24 volts is with nearly no load.

Answer 2

Your question is a bit convoluted. Not sure where the transformer comes into the question. However, the maximum DC voltage you can obtain with a full-wave rectifier is the zero to peak voltage of the input sine wave. the size of the capacitor will determine how much AC ripple voltage is imposed on the DC voltage.

Answer 3

The peak voltage from this transformer will be 18V * 1.414 = 25.452V which with a perfect filter and no load current (thus zero ripple) would be the maximum DC voltage possible from a powersupply based on this transformer and a bridge rectifier. But this would not be useful voltage as placing any load on the supply will reduce the DC voltage and increase the ripple AC voltage. Also no filter capacitor is perfect as all electrolytic capacitors have a small leakage current which will always leave some ripple AC voltage thus reducing the output DC voltage below this ideal value.

Answer 4

I would not expect to obtain any DC voltage from a transformer seeing how it is an AC device.