How to Identify Diodes

Updated February 21, 2017

Diodes are found in many electrical devices. They vary in size and are found in everything from amplifiers to computer circuitry. Because there are so many types of diodes and recognizing their individual uses and properties is important, diodes have a specific way of being identified. This identification method is the semiconductor identification system, and it allows for identification in several steps.

Identify the number of junctions of the unit. This will be the first number of the entire identification number series, and will be one less than the number of junctions. If you see two junctions on the unit, then the unit is a diode and receives the number "1."

Determine whether the diode is a semiconductor. Resistivity in semiconductors will lie between the resistivity levels of a conductor and insulator. If the diode is a semiconductor, then put a letter "N" after the number "1" in the identification series.

Identify any details about the semiconductor if applicable. Polarity is an example of a detail that could be labeled, as are modifications and matching devices for which the diode being identified could be substituted. Label the detail using another letter (suffix), such as "R" for reverse polarity, after the first two components of the identification sequence.


Be familiar with what the letters of the identification system stand for prior to trying to complete the identification process, since the letters have specific meanings and give the real detail about the diode. Additionally, look for whether the ends of the diode (anode and cathode) have been labeled by the manufacturer.

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