Homemade LED breathing light

Breathing light is a kind of decorative LED circuit that has emerged with digital products. It can be seen on mobile phones, mice, computer cases, home lamps, etc. For example, the breathing light on a mobile phone will light up when it is in the state of text messages or charging, just like the rhythm of human breathing, which will serve as a reminder for everyone. It is beautiful and practical.

It is actually very simple to make such a breathing light. Its principle is a low-frequency self-excited oscillator. In the past, the first choice for making a self-excited oscillator was often completed by a 555 circuit, but in addition to the 555 circuit, there is also an op amp circuit that can complete this function.

Figure 1 is a breathing light circuit provided by a foreign circuit website. This circuit has only one LED light for indication, which is often not obvious in some occasions. Figure 2 is an improved circuit based on Figure 1, which can be increased to 4 LEDs.

According to the above breathing circuit, since it is self-excited oscillation, the flashing of its LED is determined by its oscillation frequency. Therefore, this type of breathing lamp can not only be used for decoration, but also as a family night light at night.

The circuit can be lit up after being connected to a 12V power supply, and the LED's blinking breathing frequency can be adjusted by adjusting the adjustable resistor.