Not sure it is a right place to ask this question but I'm pretty out of options. I'm building DIY home-studio LED lights out of multiple 12V LED bulbs. I'm using a dedicated power supply connected to the mains (2 wires + ground, Central-Europe style).

When I turn the lights on the camera Mobius Action Cam starts freezing randomly but frequently (few times in 20 seconds). How is that possible? What I can do to fix the problem?

The power supply is HV-12020A and seems to be pretty well made but I have no way of looking inside - it's sealed.

  • \$\begingroup\$ Does it get worse if you bring the camera closer to the LED wiring. Ditto the LED controller. Ditto any AC wiring that might feed the controller? Are the LEDs dimmable? Does that make a difference? Is the controller a PWM dimmer type? \$\endgroup\$
    – Andy aka
    Apr 3, 2014 at 21:25
  • \$\begingroup\$ The power supply is no dimmable: HV-12020A. It might be worse when closer to it but it's hard to tell. \$\endgroup\$
    – atok
    Apr 3, 2014 at 21:36
  • \$\begingroup\$ Have you tried measuring power supply noise with an oscilloscope? \$\endgroup\$ Apr 3, 2014 at 21:46
  • \$\begingroup\$ I don't have access to an oscilloscope :( \$\endgroup\$
    – atok
    Apr 3, 2014 at 21:58
  • \$\begingroup\$ Are you using the camera on batteries or a mains adapter? \$\endgroup\$ Apr 3, 2014 at 22:10

1 Answer 1


If you make the lights shine into a box, so the actual light doesn't make it into the room, does the camera still freeze? There might be an interaction/strobing between the LED light and the sensor of the camera, which might cause, or seem like, stuttering.

If the problem still happens when the LED bulbs shine into nothing, then it's a combination of the power supply and the PSU filtering in your computer. That seems unlikely to me, but I imagine anything could happen. Try another power supply for your computer in that case. Or try running the lights off a 12V car battery...

OR it could be EMI between the lighting wiring and the USB cable. USB is a high-speed protocol, and cheap USB wiring is not always up to filtering out external EMI. USB signal degradation can also cause frame drop-outs on webcams. Try a better cable (ideally with ferrite chokes on the ends) or if the cable is not removable, reposition the cable, or try another webcam.

Finally, the data sheet I found for that power supply by Googling said "life: 3-5 years," which doesn't fill me with confidence. I like equipment to last a lot longer than that...

  • \$\begingroup\$ Thank you! I will testing for those things. One extra question: this camera has external heat sink ( two meta parts on top: dashboardcamerareviews.com/wp-content/uploads/… ) attached directly to the sensor. Is it possible that this is making the camera more vulnerable to EMI ? \$\endgroup\$
    – atok
    Apr 4, 2014 at 8:49
  • \$\begingroup\$ I would think that's unlikely, but I'm not particularly knowledgable in CMOS sensors :-) \$\endgroup\$
    – Jon Watte
    Apr 4, 2014 at 17:48
  • \$\begingroup\$ "There might be an interaction/strobing between the LED light and the sensor of the camera" -- I think that is the case. It's hard to be 100% sure but there is no problem when the room is sunlit. \$\endgroup\$
    – atok
    Apr 6, 2014 at 13:00
  • \$\begingroup\$ Also note that most webcams reduce their frame rate when the light is low. The frame rate with LED-lights-only will be lower than the frame rate with sunlight. Low frame rate is different from freezing, though :-) \$\endgroup\$
    – Jon Watte
    Apr 7, 2014 at 16:56
  • \$\begingroup\$ The issue was definitely related to the framerate/shutter speed in low light. I replaced the camera with Logitech C930. \$\endgroup\$
    – atok
    Apr 9, 2014 at 12:57

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