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minimum LED flicker rate to prevent seizures

Discussion in 'General Electronics Chat' started by mik3ca, Nov 16, 2017.

  1. mik3ca

    mik3ca Member

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    I have a project in which the RGB LEDs are on the same circuit board as Phototransistors. The Phototransistors are able to detect light from the RGB LEDs while they are on, but I want the LEDs on as often as possible.

    One idea I thought of was to turn the LEDs off to create darkness while detecting the status from the phototransistor then after the detection, turn the LEDs back on. I want to make the LED off time as small as possible.

    I also want sensing of the phototransistor to be done at least 5x a second. and I want the phototransistor to be able to detect about 2 bytes of information.

    In order to prevent seizures, what frequencies should I watch out for? and is it better to make the LED flicker faster or flicker slower? and what kind of duty cycle is best for seizure prevention?
     
  2. alec_t

    alec_t Well-Known Member Most Helpful Member

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    As far as I recall (but you should verify this) the critical frequency is around 7Hz for epileptic seizures, but presumably varies among individuals.
     
  3. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    Last edited: Nov 17, 2017
  4. dave

    Dave New Member

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  5. alec_t

    alec_t Well-Known Member Most Helpful Member

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    I think I'd rely on the figures in that second link. So, 2Hz-60Hz covers it for the majority of susceptible people.
     
  6. Diver300

    Diver300 Well-Known Member

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    If you are expecting these lights to be visible, anything below 30 Hz will be annoying to nearly everyone. 100 Hz will be visible and annoying to some people, and you have to go beyond 1 kHz for the flicker not to be visible to more than a few people, and even for them it will only if they look for it.
     
  7. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    I believe flicker is more easy perceived with peripheral vision than when you look directly at it. Call it evolution, if you will.
     

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