Announcing: Simple design notes, LEDs

I have put together a web page with some notes covering some of the things that seem to come up here from time to time when beginners start using LEDs....

http://www.arunet.co.uk/tkboyd/ele1led.htm

It only covers basics, but does go as far as selecting the appropriate current limiting resistor.

I hope this announcement will help people in the future quickly find the answers to some of the common questions, without having to wait for answers to questions at the forum. And I hope it will incite some of the experienced designers at the forum today to have a look and let me know of any mistakes before some poor beginner is confused by them.

If you are writing to say "this/ that/ other" is wrong, could I invite you to do so by private message? I don't care if you announce my boo-boos in public, but it just seems unnecessary to have the post pop up to the top of the forum list again and again when I'm going to be revising the page in the light of suggestions anyway.

Suggestions for things which ought to have been mentioned on the page also welcome.

Thanks, Tom

You suspect that pulsing might make the LED appear brighter. However this is not true. I remember at least one investigation where they come to the conclusion that depending on the frequency pulsed lights will appear dimmer.

Also the efficiency of LEDs will decrease beyond some current levels. Again you will get less light per average current then by not pulsing.

Usuaally the reason for PWM is dimming. AFAIK there is no known means to make it appear brighter on a given average current with high frequent PWM.

Udo