Two-Rail O and S Scale DC and DCC Voltage

[Randall_Roberts]

I know AC systems use 18VAC.  What voltage level do two-rail O and S scale trains use?  And what is the +/- pulse amplitude for DCC in these two-rail sytems?

Thanks,

[IRONROOSTER]

For my S scale I use an MRC 9500 and a Tech II 2500.  I think they top out at 12v DC. I have an American Models GG1 and Showcase SW1 and SW9. 

Enjoy

Paul