This circuit produces pulses of great intensity and short duration at a frequency of approximately 1 kHz. We can use this circuit as part of an infrared remote-control project that listens for pulsed signals. Any common infrared LED can be used and the resistor in series with the LED, which determines the emission power, can have values between 10 ohms and 56 ohms. It will be interesting to check the characteristics of the LED used to obtain the ideal value for this resistor.
