Circuit with V AC and V DC after rectification
I'm going to go out on a limb and take a guess that your other question about reading AC and DC relates to this question ..

If you're feeding regular AC through a full-wave rectifier (the four diodes you mention), the resulting waveform may well give you funny readings on ordinary DVMs. The waveform will resemble the absolute value of a sine wave, and still has enough AC character that a $50 DVM will likely show you a significant reading, albeit an incorrect one. 

Using a DVM to try to figure out a circuit like this gets you into the murky territory of the 'true RMS' problem. DVMs are all over the map with regard to how well they perform at giving correct RMS readings. And even if you have a meter that's dead on, this number may not tell you what you really want to know. In situations like this, an oscilloscope is the preferred instrument, and you can get PC/USB based ones for under $100 that will perform admirably at AC line frequencies.