I need to make an IR transmitter (codes for air conditioning) on an ESP8266. As usual, I decided to check for ready-made circuits. I found one on Ali:
This is both a receiver and a transmitter, and has pins for programming. What puzzled me were the components on the board - there is only one 1k resistor - presumably connected to the base of the transistor that controls the IR diode. However, there is no resistor to limit the current of the diode (there is nothing on the other side of the board). I wonder how this works? The diodes can handle about 200mA when pulsed, the control transistor is about 500mA and the stabiliser is capable of giving 1A. The ESP is usually powered from the mains - so you can't rely on the internal resistance of the cell.
This is both a receiver and a transmitter, and has pins for programming. What puzzled me were the components on the board - there is only one 1k resistor - presumably connected to the base of the transistor that controls the IR diode. However, there is no resistor to limit the current of the diode (there is nothing on the other side of the board). I wonder how this works? The diodes can handle about 200mA when pulsed, the control transistor is about 500mA and the stabiliser is capable of giving 1A. The ESP is usually powered from the mains - so you can't rely on the internal resistance of the cell.
