Can the diode setting of a multimeter light up a diode?
There is a diode gear on the multimeter that can be used to detect diodes and turn them on. But the lighting is not absolute, there are two main reasons: 1) the diode gear voltage of the multimeter is low; 2) The working voltage of light-emitting diodes is relatively high.
The voltage of the diode gear of a multimeter is generally around 3V, which can light up ordinary light-emitting diodes. When measuring the quality of a diode, the red probe can be connected to the positive terminal of the LED, and the black probe can be connected to the negative terminal of the LED. If the LED lights up, it can be judged that the LED is good. However, some meters cannot light up the LED or can only light up slightly when the output voltage is low. I have used a relatively cheap multimeter from Ulide before, but it couldn't light up the LED, and the diode gear was basically useless, which was very inconvenient.
LED is a special type of diode with forward conduction voltage drop, and this parameter varies greatly. The conduction voltage drop of different colored light-emitting diodes varies. Generally speaking, the conduction voltage drop of red light-emitting diodes is the smallest, with a range of approximately (1.5-2) V; Green is second, around (1.8-2.5) V; The blue voltage drop is the highest, around (2-3.5) V. So, when measuring LEDs of different colors on the same meter, their brightness varies. Generally, red is the brightest and blue is the darkest. Even some colors cannot be illuminated.
