- Edited
Check our oscilloscope thread, the methods developed there are working very well for lighting. Make sure to read all replies, as the info is scattered across the thread.
https://ledstrain.org/d/312-homemade-oscilloscope-to-detect-pwm-diy-guide
@everyone: you need to understand one thing, which is not obvious and may cause disbelief: even extremely small fluctuations can cause symptoms. That is the most important thing I have discovered over time. By tiny I mean fluctuations that you cannot discover with the camera/smartphone methods. You need something more accurate. And frequencies > 20 kHz can still cause symptoms. I think both of those statements go against anything you'll currently read and hear anywhere else about lighting safety and medical knowledge, but if you already know you're sensitive to flicker it is super important that you get the right tools to check out if this level of sensitivity applies to you, too. Cameras are not the right tools. You will never capture fluctuations smaller than 1% with a camera. Not to mention the "pencil" method. Feel free to ask if you need more info.