Diode mode multimeter (manual and instructions for use)
Tools and Tips

Diode mode multimeter (manual and instructions for use)

19.02.2023 /

A diode is an electronic device that allows current to flow through it in only one direction, not the opposite. Semiconductor diodes usually have a general design principle, which is a P-type semiconductor block connected to an N-type semiconductor block and connected to two terminals, namely an anode and a cathode.

A rectifier circuit is an electronic circuit containing electronic components that convert alternating current to direct current. Rectifier circuits are used in DC power supplies or RF signal detectors in radio equipment. The rectifier circuit usually contains semiconductor diodes to control the current and mercury rectifier lamps or other components.

In general, the best way to test a diode is to use the "Diode Test" mode on your multimeter, because this mode is directly related to the characteristics of the diode. In this method, the diode is forward biased. A normally operating diode will carry current when forward biased and should have a voltage drop. If the displayed voltage value is between 0.6 and 0.7 (for a silicon diode), then the diode is good and healthy.

Diode measurement steps in the "Test Diode" mode

  • Determine the positive and negative poles of the diodes.
  • Keep your digital multimeter (DMM) in diode test mode. In this mode, the multimeter is capable of delivering approximately 2 mA between the test leads.(2)
  • Connect the black test lead to the negative terminal and the red test lead to the positive terminal.
  • Observe the readings on the multimeter display. If the displayed voltage value is between 0.6 and 0.7 (for a silicon diode), then the diode is good and healthy. For germanium diodes, this value ranges from 0.25 to 0.3.
  • Now swap the meter terminals and connect the black probe to the positive terminal and the red probe to the negative terminal. This is the reverse bias state of a diode when no current flows through it. Therefore, the meter should read OL or 1 (equivalent to open circuit) if the diode is good.

If the meter shows values ​​that are not related to the above two conditions, then the diode (1) is faulty. Diode defects can be open or short.

Conclusion

In this article, we have detailed instructions on the "Diode Test" mode for measuring diodes. We hope that the knowledge we provide will help you learn more about power tools.

Recommendations

(1) Diode information - https://learn.sparkfun.com/tutorials/diodes/all

(2) Multimeter information - https://www.electrical4u.com/voltage-or-electric-potential-difference/

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