led persistence
led persistence
(OP)
if a 20ma rated led is pulsed at 20ma, how often (frequency) would it have to be pulsed to maintain the illusion that it is on continuously? or do i have to pulse it harder (>20ma) to give the illusion?
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RE: led persistence
Dan - Owner

http://www.Hi-TecDesigns.com
RE: led persistence
RE: led persistence
I would have expected an annoying flicker without vibration at that refresh speed
Dan - Owner

http://www.Hi-TecDesigns.com
RE: led persistence
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RE: led persistence
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
Chinese prisoner wins Nobel Peace Prize
RE: led persistence
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
Chinese prisoner wins Nobel Peace Prize
RE: led persistence
RE: led persistence
Keith Cress
kcress - http://www.flaminsystems.com
RE: led persistence
RE: led persistence
For an "ordinary" LED you may well find that you can't get the brightness at the duty cycle you require without exceeeding the maximum pulse current. Consider hyper-bright LEDs from manufacturers such as Avago - really bright on just a few milliamps. (Usual Disclaimer)
RE: led persistence
What is the final application? Certain types of LEDs can be pulsed at higher than rated currents for short time periods and give a perceived increase in brightness compared to their average DC power.
Dan - Owner

http://www.Hi-TecDesigns.com
RE: led persistence
RE: led persistence
However, LCD displays currently have about 8 ms of persistence, so LCD frame rates need to be much high to mitigate flicker. LEDs basically have no persistence, which can often be seen on LED brake lights or traffic lights. When they're turned off, it's immediate and abrupt.
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Chinese prisoner wins Nobel Peace Prize
RE: led persistence
RE: led persistence
Keith Cress
kcress - http://www.flaminsystems.com
RE: led persistence
RE: led persistence