Been thinking about starting a tutorial on basic analog circuits and why not with rectifiers and regulators seeming thqt they are in the base of everything that can be called electronics. So you all know that the form of electricity that come from the outlets is AC (220V/60hz for europe). Besides the fact that you'll need to step it down to a lower voltage with the appropriate transformer you'll also need to rectify it so that it becomes DC. Next you'll need to filter it because the load will continuously power on/off. There are a few ways to do that. The most basic one is to use a half wave rectifier but it requires heavy filtering (LC or only C) and utilizes only half of the whole wave==>utterly inefficient. By using a full wave bridge rectifier you sorta rectify both waves to become a 120Hz DC. Now that will require less filtering and will provide the full wave for rectification==>increase of efficiency. Another think I would like to point out is that after the rectifier the voltage will drop around 1V (depending on the type of diodes you've used Si,Ge) but you'll regain that 1V when you put the capacitor. Then you'll have to multiply the -1V voltage by 1.41V (derivative from the peak voltage formula). The result will easily kneel under a load especially if you're transformer is weak. So everything is fine until...those damn voltage ripples introduce an audible hum in amplifiers or glitches in digital devices and many other unwanted phenomena into electrical devices.Then a regulator may come handy. There are a few ways to do it. Either use a linear aka parametric regulator which ive shown to smoothen the ripples or use a switching regulator. There are a lot of more things to say like efficiency,some explanation about transformers, regulators and types of regulators and many other stuff but I wont post it as a description but rather if you have any questions just post a comment and I and many other technicians in EC will be happy to reapond ;)