Electronic Circuits and Projects Forum

unix60959 I think if you are posting vids they should be visually clear, that means no wobbles as the camera moves and then the vid should stand Technically, the notion that most LEDs are 0.7v is wrong.

You could add a "confirmation" (of the LED current), by measuring the voltage across the Resistor. I think that would satisfy the several issues pointed out by other posters. A DVM might not show on the screen, but a cheapie m/c multimeter has minimal burden for this measurement.

Keep on trucking.

well guys after those negative comments how we can calculate the resisor for the LED??in that case

R = (Vs - Vf) / Iled where Vs is the voltage of a well-regulated supply, Vf is the nominal forward voltage of the LED at the design current and Iled is the design current.

Originally Posted by ericgibbs

hi,
Try this calculator, if you have a problem let me know.
http://www.electro-tech-online.com/t...calculator.php

i saw it and i got one quesition please
what is the Maximum Permissable LED current Limit milli-amps??

i think that Maximum Permissable LED current Limit milli-amps is that maximum value of current that LED can work on it after it the LED is break down or operate at reverse mode??

if i9 wrong you tell me,vuz iam beginner

thx dude.

Originally Posted by Sceadwian

This is the current limit for the LED.. Pretty basic. The vast majority of common LEDs have current limiteds of 20ma, with some bright LEDs handling 30ma without much trouble, beyond that it's up to the datasheet for your specific LED.

It has nothing to do with reverse conduction of a diode this is not taken into consideration in a resistor calculator typically.

If you want to be safe, assume this current is 10ma and run your calculations from there, your LED's will last many times longer than one run at it's fully rated current and will consume less power but still provide an appreciable amount of light. Considering the main goal of many LED setups is to simply be able to be seen (often in the dark) not necessarily as primary illumination extracting every lumen of brightness out of the diode isn't as high a goal as you might think. Given running a diode at 10ma vs 20 consumes half the current, it generates 1/4 the heat and more than doubles the LED life yet will produce more than 50% of it's rated light output at full current, so it's always more efficient to under current an LED from it's maximum specs.

that was pretty but if the current value exceed Maximum Permissable LED current Limit milli-amps??
what is gonna happen ??