The triode in the figure is an 8050 triode, which is a current control type. If the io port of the microcontroller has a 200K pull-up, is the base voltage high or low? Can the LED light up?
Connie Veröffentlicht am January 15, 2021
High level
Jaycee Veröffentlicht am January 15, 2021
There may be a problem with the actual circuit
Alonzo Veröffentlicht am January 15, 2021
1. It is best to connect a resistor in the base of the triode;
2. There is no need to use a pull-up, it is better to add a pull-down resistor between the NPN transistor and BE; in fact, the MCU generally has a weak pull-up;
3. If the LED voltage of the load is relatively low, such as about 2V;
It is possible to use 3.3V for the LED power supply, otherwise it is best to use 5V;
If it is a low-voltage LED, the LED can be directly connected to the IO of the microcontroller, and then a resistor is connected to the power supply;
One resistor + 1 LED is enough, which is simple and reliable;
