![voltage - Driving a high power (200mA) LED with a GPIO and NPN transistor - Electrical Engineering Stack Exchange voltage - Driving a high power (200mA) LED with a GPIO and NPN transistor - Electrical Engineering Stack Exchange](https://i.stack.imgur.com/hnyLl.png)
voltage - Driving a high power (200mA) LED with a GPIO and NPN transistor - Electrical Engineering Stack Exchange
![NPN LED Driver - Why an extra resistor to ground at the Base? | Electronics Forum (Circuits, Projects and Microcontrollers) NPN LED Driver - Why an extra resistor to ground at the Base? | Electronics Forum (Circuits, Projects and Microcontrollers)](https://i.imgur.com/uiVisGR.jpg)
NPN LED Driver - Why an extra resistor to ground at the Base? | Electronics Forum (Circuits, Projects and Microcontrollers)
I'm using an npn transistor to turn one led off while the other is activated by a button, but if a resistor is before the other led, a low current passes from
![NPN Transistor With Three LED's as a Switch | IamTechnical.com | Electronics basics, Transistors, Simple electronics NPN Transistor With Three LED's as a Switch | IamTechnical.com | Electronics basics, Transistors, Simple electronics](https://i.pinimg.com/originals/cf/44/d4/cf44d43dc1324d0097b5e9838c847944.gif)