Diode is widely used as a rectifier of AC power into DC and many applications in electrical engineering and electronics. Diode has two legs, namely Anode and cathode. To find out how to work as a rectifier diode we see two series diode connected to Diode circuit shows positive DC voltage is connected Cathode footed, looked no current flows or Diode in a position to block the flow, This condition is called fallback position (reverse). Characteristics of a Diode illustrated by the horizontal axis to voltage (Volt). The vertical axis to show the current (mA until Amperes). Positive voltage (forward) calculated from zero to the right axis. Negative voltage (reverse) begins negative axis to the left. Current line forward (forward) axis starts from zero and above by units of Ampere. Current line backward (reverse) axis begins with zero down to the order of mA. Diode has a reverse voltage withstand limits on certain value. if Diode reverse voltage is exceeded it will be permanently damageda DC voltage source. Diode circuit with a source DC voltage showed a positive DC voltage Anode is connected to the leg, the This condition Diode DC current drain can be seen from the appointment ampermeter with the flow If, for voltage is called the forward voltage Uf (forward). Silicon diode will begin forward when it has reached a voltage cut-in of 0.7 volts, for Diode germanium cut-in voltage of 0.3 Volt.