Flashlight flickers/strobe effect on low mode

fiyimu · January 13, 2019, 12:46pm

Hey,
I have two flashlights - cheap Utorch XPL V6 and Convoy S2+ (it’s cheap too actually). Utorch has flickering effect on low mode and S2+ doesn’t have it. I’ve made a video:

The flickering effect is very annoying (it’s not visible only in camera. In real life it’s visible as very fast strobe effect) and I’m using flashlights on low mode mostly. What can I do with this? Is is fake Cree in Utorch? I saw such flickering effect in other very cheap-no name flashlights too.

Lexel · January 13, 2019, 3:52pm

low frequency PWM used on UF driver

Convoy uses PWM of about 16kHz

replace with a Biscotti or Bistro driver

hank · January 13, 2019, 5:17pm

https://learn.sparkfun.com/tutorials/pulse-width-modulation/all

https://www.google.com/search?client=firefox-b-1-d&q="flicker+frequency"

People can see lights flashing on and off up to about 50 flashes per second (50 Hz) - they are most sensitive to time-varying illumination in the 10-25 Hz range. The actual critical flicker frequency increases as the light intensity increases up to a maximum value, after which it starts to decrease. When a light is flickering at a frequency greater than 50 or so Hertz, most people can no longer distinguish between the individual flickers. At this frequency - the critical flicker frequency or flicker fusion threshold - the flashes appear to fuse into a steady, continuous source of light. This happens because the response to the light stimulus lasts longer than the flash itself.

Most people cannot notice the flicker in fluorescent lights that have a flicker rate of 120 cycles per second (or 120 Hz). Flicker with LED lights may be more noticeable due to the fact that LED lights flicker between less than 10% and 100, where as fluorescent lights dim to about 35 and back to 100%).

The light flicker may be detected by its stroboscopic effect. When objects move or rotate rapidly, they may be lit at or about the same position during each cycle or rotation. This makes objects look as if they are moving more slowly than their actual speeds - they may even appear stationary if the object is moving at the same rate as the flicker frequency (or a multiple of it). This fact is the principle behind a strobe light but it is not the desired effect in general lighting. In fact, it could be a safety hazard if someone mistakenly thought that some equipment was stationary or was moving slowly.

fiyimu · January 14, 2019, 12:30pm

Oh man, it sucks. I will just sell that flashlight

MascaratumB · January 14, 2019, 5:43pm

If you are sensitive to that effect, there is few you can do unfortunately! The best thing is to get a flashlight that doesn’t produce that PWM effect or one that is not noticeable in you naked eye!

Probably a good option You will be able to find replacements for sure!!