Understanding Semiconductors, Lecture 7

How to find out the anode & cathode using a multimeter?

Procedure for finding out anode and cathode –

  1. Take a multimeter and put it in ohmmeter range.
  2. RED probe is positive and BLACK probe is negative.
  3. Connect two probes to two terminals of diode, AT RANDOM.
  4. If the multimeter DOES NOT DEFLECT, reverse the probes connections.
  5. Now if the multimeter deflects, the terminal connected to RED probe is anode.
  6. And the terminal connected to BLACK probe is cathode.
  7. Refer the following diagram for connections.

Procedure for checking the diode for faulty or OK condition –

  1. Take a multimeter and put it in ohmmeter range.
  2. Condition 1: Connect RED probe to anode, BLACK probe to cathode.
  3. Note down the deflection of multimeter.
  4. Condition 2: Now reverse the connections.
  5. Note down the deflection of multimeter again.
  6. The result of testing is as follows –
  7. If multimeter deflects only in one condition, the diode is OK.
  8. If the multimeter deflects in both conditions the diode is FAULTY.
  9. If multimeter does not deflect in both conditions, the diode is FAULTY.
  10. Refer the following diagram for connections.