dummer

The DC voltage is roughly the square root of 2 times higher, minus the voltage drop across the rectifier diodes, when properly smoothed, and without a load. Could you show the math? Let's say the AC voltage came out of a transformer at 40VAC.

I need to build a power supply for a CNC machine. I've been told that the resultant DC voltage will be slightly higher than the non-rectified AC. Can someone tell me the precise factor used to compute the new voltage?