I saw how this application (Cardiograph) uses a bright flashlight, and then it switches to a dim one. The phone itself (Samsung Galaxy A10s) does not have a built-in flash brightness control, and there is no root either. So, how can you adjust the power of a flashlight, what applications are there for this (maybe even somehow through Termux)? Samsung Galaxy A10s phone, Android 11, all updates installed.


  • 1
    I assume the app is simulating dimming by letting the LED flicker in a high frequency.
    – Robert
    Commented Sep 30, 2022 at 15:52
  • @Robert No, the LED does not blink in any way, it is a static light.
    – Pushistik
    Commented Sep 30, 2022 at 21:02
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    You will see blinking only if the frequency is low. If it is higher than 100 Hz humans will not recognize it as blinking. But I am not sure if you can switch the led so many times a second.
    – Robert
    Commented Sep 30, 2022 at 22:04
  • 1
    Adjusting flashlight brightness is a new feature in Android 13. On Android 12 and older there is no universally working solution. Some app developers tried to "misuse" flash modes and preview mode, while others tried to write directly to /sys/class/leds/. None is guaranteed to work on all devices. Except that the OEM or custom ROM developer has already added the option in Settings. Commented Oct 2, 2022 at 20:13
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    And I just checked. The app you've mentioned uses the both APIs: flash mode and preview mode. The latter seems to do the trick on Samsung devices. Commented Oct 2, 2022 at 20:23

1 Answer 1


From googling, I found How to adjust the flashlight brightness on your Samsung Galaxy phone;

  1. Tap the word “Flashlight“ below the icon to open the brightness slider.
  2. Alternatively, you can long-press the Flashlight icon itself to access it.
  3. Adjust the slider from Level 1 to Level 5 as you desire.
  4. After choosing a brightness level, tap Done to leave the setting.
  • Samsung Galaxy A10s doesn't have this option.
    – Pushistik
    Commented Oct 3, 2022 at 16:23
  • I found that too, but I wonder if instead or torch he means flash for taking pictures
    – Archerbob
    Commented Oct 3, 2022 at 17:16

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