I'm looking for the simplest analog method to adjust an LED's brightness based on a voltage ranging from 0 to 3.3V. I want 0V to mean the LED is off and 3.3V to make it as bright as possible. However, since typical forward voltages are around 2V, I'm not sure how to connect it directly. Any tips or designs would be greatly appreciated!
2 Answers
To match the voltage to the LED's brightness, you'll want to control the current flowing through it. Simply adjusting the voltage isn’t safe since a small change in voltage can cause a huge spike in current and potentially burn the LED out. A good approach is to use an operational amplifier (op-amp) to help regulate the current. You might also consider using PWM (Pulse Width Modulation) to dim the LED, though that can be more complex without a microcontroller.
If you're just trying to adjust the brightness within the LED's operating range, consider using a current mirror. By varying the current in a ‘master’ circuit, you can have ‘slave’ circuits that follow that current, which keeps the brightness of your LEDs consistent since they rely on current.