This is a simple project I created to test how transformers work in EasyEda. A transformer is a device composed of two inductances called primary and secondary and it is used to transforms AC Voltage in another. When a wire is crossed by a current it generates a magnetic field that becomes larger if the wire wound around an iron core. The two spiral wires are called primary and secondary. The former is connected directly to the AC Power (In Italy 230V) the latter to the circuit. If the primary has N ring we will have 230/N Volt per ring. For example, suppose the primary has 1000 rings we will have 230/1000=0,23 V per ring. The question now is: how many rings we need on the secondary to have a 12 V? The answer is 12/12.3=53 rings. The primary/secondary Ratio is 52/1000=0.053 and this is the exact value I put in the Transformer field to convert 230V AC in 12V AC.