Dioditesti

Dioditesti (Finnish: "diode test") refers to a diagnostic procedure used to verify the electrical behavior of diodes and other semiconductor rectifiers. The term is commonly associated with the diode-testing function on digital multimeters, which applies a small test current to measure the forward voltage drop of a diode and indicate whether it conducts in the expected direction.

During a diode test the meter places a known small current through the component and displays the forward voltage (typically in volts) when the diode is forward-biased. A good silicon diode usually shows around 0.6–0.7 V, Schottky diodes lower values (roughly 0.15–0.45 V), and LEDs show higher, color-dependent forward voltages. When reverse-biased a healthy diode should show very high resistance or an overload indication; a reading of near zero in either direction suggests a short, while a consistently open reading suggests a break.

Limitations of dioditesti include inability to detect certain faults in-circuit, influence from parallel components, and insufficient test voltage to trigger zener breakdown. Proper testing typically requires the circuit power to be removed and the diode isolated if in-circuit readings are ambiguous. For more detailed characterization, curve tracers or dedicated semiconductor testers provide current-voltage curves and dynamic parameters. Safety precautions include disconnecting power and discharging capacitors before probing.