A transformer also known as eliminator is a device that converts or Steps down[also steps up] a high voltage (eg.230V,120v) AC to a safe voltage like 12V,6V,3V etc, through induction coils, but there are many kinds of transformers eg.step-up transformers,step-down transformers,audio transformers..) so here we will learn about step down transformers, every step-down(all basic transformers have though) transformer has two sides which are known as The primary side and The secondary side, the primary side is connected to high voltage 230vAC or 120vAC(Some countries use 120vAC Instead of 230vAc) eg.To a wall socket at our house, then we get the transformer’s rated output like 12vAC from the secondary side of the transformer, but you can’t use the AC output of the transformer to power anything that requires DC!. what is dc? the AC voltage is not stable as the movement of electric charge in AC periodically Is reverses direction! But in DC, The voltage is direct. To power a required device that needs DC you have to change the AC to DC! How to do that? Its Easy, you just take a diode and connects its Anode terminal to one of the transformer’s outputs, so you get +V DC output from the diode’s kathode terminal, but it is not pure DC! You need a bridge of diodes(full wave rectifier) in order(center tapped transformer needs only 2 diodes) to make it almost pure DC, moreover you need a filter capacitor across the outputs to filter supply even more and remove ripple, some photos are here to guide you!!
Dual Power Supply.