Half wave rectification may be achieved with an alternating voltage connected in series with a diode - resistor combination. Full wave rectification may be achieved with a slightly more complicated circuit consisting of four diodes arranged in a bridge connection, shown below. The result is an output at twice the frequency of the supply voltage.
Note that the diodes are all away from the input and towards the output. Rduring one half of a cycle current flows from A to B and C and during the other half of the cycle current flows from D to B and C.
The output can be smoothed by placing a capacitor in the circuit as shown.
The resulting output is shown below.
