You have used a schematic symbol for the bridge rectifier that has no simulation model associated with it. Please see (3) in: https://easyeda.com/andyfierman/Welcome_to_EasyEDA-31e1288f882e49e582699b8eb7fe9b1f

thans Andy @andyfierman

@gdisimone hi andy i built the bridge with 4 diodes; I used a Vmax ac 56v (f=50hz), Rl=45k and the circuic working correctly, but when i put a C> 800microF,Vout is instable: why? if i increase the capacity Vout should be more stable. Thanks in advance, best regard

Your project is private so only you can see it so I am guessing what might be happening. I suspect you are running the simulation with unsuitable time values. If you are running the simulation with a mains frequency of `F` then set the Stop Time to about `10/F` or less if the smoothing cap has charged up sooner. Set your (Stop Time)/(Max Timestep) to 1000.

You also need more than 1V peak to peak from V1. The forward drop of a bridge rectifier with silicon diodes is between about 1V to 2V depending on the load current! https://easyeda.com/andyfierman/Bridge_rectifier-e5be2d957e1044e5bad584566223e2a1