Infrared blaster
An infrared blaster (IR blaster) is a device that emulates an infrared remote control to autonomously control a device that is normally controlled only by keypresses on its remote control. The most common use of an IR blaster is to allow a recording device, such as a DVR or VCR, to change the channel on an external tuner, such as a cable box or satellite television receiver. This way, the receiving device can automatically select the correct channel to record before starting the recording process. Two other common uses are to extend infrared signals in order to place  remote-controlled products behind closed doors and to allow mobile devices to control infrared devices. In the mid-2010s, many smartphones included IR blasters; most but not all manufacturers stopped including this feature by 2018. Some smartphones released after 2018 include an IR blaster, for example Xiaomi MI 9. Description. In an IR blaster device, one digital signal modulates a light source to send commands to other devices. This signal of IR blaster is invisible to the human eye, because its wavelength is beyond the range of visible light. The signal does not affect the human body and has no side  effects for long exposure. The IR blaster can control TVs, air conditioners, DVD players, and many other devices, and can replace the functionality of remote controls. Applications. The main use of the IR blaster is to control other secondary devices through a primary device configured with the IR blaster. IR blaster can be used to control devices, such as television sets, DVD, VCD, air conditioner, and entertainment systems. IR blasters can sometimes be found integrated in some Android smartphones such as the Xiaomi Mi 9. Recently bluetooth devices have started replacing IR blasters. Dedicated IR blaster devices are also available  that connect with mobile phones via the 3.5 mm audio jack.