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Is the LED not lit due to insufficient voltage?
Light-emitting diodes are also called LEDs. LEDs have been covered at all levels, from lighting design to indicating reminders, LEDs are involved. Will explain to everyone the phenomenon that the LED in the circuit is not bright, see if the reason why the LED is not bright is caused by insufficient voltage, or caused by the drive current is too small?
Case: The total voltage of the circuit is 3V and the resistance is 580 ohms. When a 3V LED is connected in series, the LED is lit. The voltage and resistance remain the same. What caused the LED to not light up?
It is known from the case that since the total voltage is 3v and the resistor is connected in series to cause voltage division, this causes the diode's resistance to be too small to reach its turn-on voltage (about 0.7v) and therefore cannot be turned on. Divide the resistor in parallel to the current on the diode. Do not let the current exceed the rated value. The wiring should be calculated in advance to determine whether it meets the standard. If it is not standard, you can replace it with another power supply.
There is also a convenient way to illuminate with a red LED, because the red LED voltage is relatively low and is easier to illuminate. But this method does not solve the problem fundamentally. Therefore, it is especially important to be fully familiar with the tube pressure of LEDs.
Tube pressure of various LEDs:
Red and yellow are generally 1.8 to 2.2;
Blue-green is generally 3.0 to 3.6;
Ordinary LEDs have a positive bias voltage drop of 1.6V, a yellow color of about 1.4V, and a blue-white color of at least 2.5V. The working current is about 5-10 mA.
Super bright LEDs are mainly available in three colors. However, the voltage drops of the three LEDs are different. The specific voltage drop reference values are as follows:
The red LED has a voltage drop of 2.0--2.2V;
The voltage drop of the yellow LED is 1.8-2.0V;
The green LED has a voltage drop of 3.0-3.2V.