I want to know about the PWM frequency to be applied to PWM driver in street light luminary. Is frequency near 400Hz to 1000Hz OK.

What is criteria for the PWM frequency for the street light application


  • \$\begingroup\$ 1k is better due to higher peripheral eye motion flicker. \$\endgroup\$ Aug 7 '18 at 6:17
  • \$\begingroup\$ OK But do we need to go compulsorily at higher side like 3K or 5K. or 1K is sufficient \$\endgroup\$
    – techsavvy2
    Aug 7 '18 at 6:31
  • \$\begingroup\$ Check led-professional.com/resources-1/articles/… \$\endgroup\$ Aug 7 '18 at 6:40
  • 1
    \$\begingroup\$ Make sure you look up the driver in the fixtures as it may have a maximum frequency. \$\endgroup\$
    – K H
    Aug 7 '18 at 7:20

The term you need to search on is Flicker Fusion Threshold Quoting from part of the wiki article, we have this:

In some cases, it is possible to see flicker at rates beyond 2 kHz in the case of high-speed eye movements (saccades) or object motion, via the "phantom array" effect.[20][21] Fast-moving flickering objects zooming across view (either by object motion, or by eye motion such as rolling eyes), can cause a dotted or multicolored blur instead of a continuous blur, as if they were multiple objects.

You need to think not only about what the eye can directly perceive, but possible stroboscopic effects

  • \$\begingroup\$ Cool. How fast would I need to pedal my bike with 36-spoke wheels to get the reverse wagon-wheel rotation effect with a 1 kHz strobe? On my 711 diameter wheels it's 62 mm between spokes. To move, say, 60 mm in 1 ms I'd need to be moving at 60 m/s = 216 km/h. It's not going to be an issue, apparently. \$\endgroup\$
    – Transistor
    Aug 7 '18 at 11:48
  • \$\begingroup\$ @Transistor It may be an issue depending on how fast your car is travelling past an array of regularly spaced objects like railings. And it depends on angular as well as linear speed. Right now, in an office with LED lighting, I can see multiple images of my fingers when I move them in front of my eyes. \$\endgroup\$ Aug 7 '18 at 12:50

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