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“Despite the energy efficiency benefits, some LED lights are harmful when used as street lighting,” its website reads. It explains that while the lights appear white to the human eye, they are actually blue, which can make nighttime glares more harsh for eyes and can lead to discomfort.
What frequency can a human no longer detect blinking?
When a light is flickering at a frequency greater than 50 or so Hertz, most people can no longer distinguish between the individual flickers.
Why do my LED lights make a high pitched noise?
High-frequency noises can be generated by the switching power supply. Such power supplies work with a switching frequency in the kilohertz range, whereby the components can also be excited to vibrate. Sometimes the switching frequency still lies in the audible frequency spectrum.
Are LED lights bad for a person’s health?
Very bright LEDs may cause retinal damage if viewed directly. Night-time exposure to bright LEDs rich in blue light can also alter the body clock and lead to various health problems. LEDs can exhibit flicker, which can cause headaches, eyestrain or epileptic seizures in some people.
Why does light not change if led is pulse driven?
Thus far, “it has been believed that, due to the Talbot-Plateau effect, the brightness perceived by human eyes would not change even if an LED is pulse driven,” Jinno said.
Can a led be driven at a constant current?
LEDs can be driven at a constant current, or they can be driven with a pulsed current. With constant current you have to limit the current to a relatively low value – for instance many common small LEDs are limited to a constant current of say 20mA. That gives good brightness for indication purposes, but it’s not that great.
Can a PWM pulse be more than 1%?
However, there are restrictions on what the pulses can be – typically with limits on the frequency and duty cycle – maybe as little as 1% duty.
Why are PWM used to control LEDs even when they are only?
They are duplicated with incandescent bulbs because their intensity can only be controlled by controlling the resistance of the filaments. That’s why dual-filament bulbs are/were commonly used as combined tail/brake bulbs. However, with LEDs you can easily control intensity with a PWM circuit.