4 ms·

I feel the same way. If I'm sitting still I find I don't care much... but if I'm working with my hands and moving around it drives me crazy and gives me headach

I feel the same way. If I'm sitting still I find I don't care much... but if I'm working with my hands and moving around it drives me crazy and gives me headaches, especially if I'm focusing on something spinning. Just for fun, I replaced the LED dimmer in my garage with a homemade board that has a frequency knob in addition to a duty cycle knob. I've found that the cutoff for bothering me is around 10KHz, which is far higher than I'd have ever expected.

amluto 3y ago
You should consider talking to the researchers who developed IEEE 1789. 120 Hz is problematic for many people, but 10kHz seems unusual unless you’re a camera.
- jcalvinowens 3y ago
  It's specifically fast spinning objects that get me: I was spending a lot of time staring at a 3400rpm grinder wheel with a fine repeating pattern on it. If I'm just sitting typing on my laptop, even the 120hz ones don't bother me.
namibj 3y ago
Could it be that you inadvertently smoothed the visual flicker on the electrical side? Consider fast brightness sensor with known (ideally approximately linear) sensitivity to the AC component of brightness, and check with an oscilloscope or so. A soundcard with 96 kHz sample rate should probably have a high-enough filter cutoff to be quite and easily useful there, though I'd see to check the frequency response with an edge generator to confirm that it has linear sensitivity from low-ish frequencies to the >=10 kHz ones of particular interest.
- jcalvinowens 3y ago
  That's a great point: above some frequency, the inductance of the system starts to average the voltage like the output of a switching power supply. I did think of that: I used a camera with a rolling shutter image sensor and manual exposure settings to prove to myself the LEDs were really still getting the full swing at higher frequencies. Also, to be clear, I'm talking about 12VDC COB LEDs with hard on/off PWM dimming, not A/C ripple. I don't know, but I'd expect the cutoff frequency to be a lot higher. The self inductance of 30ft of 16awg wire is about 20uH. I should test it...

amluto 3y ago

You should consider talking to the researchers who developed IEEE 1789. 120 Hz is problematic for many people, but 10kHz seems unusual unless you’re a camera.

jcalvinowens 3y ago
It's specifically fast spinning objects that get me: I was spending a lot of time staring at a 3400rpm grinder wheel with a fine repeating pattern on it. If I'm just sitting typing on my laptop, even the 120hz ones don't bother me.

namibj 3y ago

Could it be that you inadvertently smoothed the visual flicker on the electrical side? Consider fast brightness sensor with known (ideally approximately linear) sensitivity to the AC component of brightness, and check with an oscilloscope or so. A soundcard with 96 kHz sample rate should probably have a high-enough filter cutoff to be quite and easily useful there, though I'd see to check the frequency response with an edge generator to confirm that it has linear sensitivity from low-ish frequencies to the >=10 kHz ones of particular interest.

jcalvinowens 3y ago
That's a great point: above some frequency, the inductance of the system starts to average the voltage like the output of a switching power supply. I did think of that: I used a camera with a rolling shutter image sensor and manual exposure settings to prove to myself the LEDs were really still getting the full swing at higher frequencies. Also, to be clear, I'm talking about 12VDC COB LEDs with hard on/off PWM dimming, not A/C ripple. I don't know, but I'd expect the cutoff frequency to be a lot higher. The self inductance of 30ft of 16awg wire is about 20uH. I should test it...