led lamp project

[MrAl]

Hi,

I agree that a 12v battery is better for this project because there is less power loss using white LEDs.
For 12v we can use three white LEDs in serie per string which leaves only 1.5v, while using a 6v battery we would have an overhead of 2.5v which is not only more but in relation to the 3.5v LED it's a lot more percentage loss.

A switching regulator could be used but it would probably be a waste of time if the voltages are matched as well as they are with a 12v battery. With a 6v battery if for some reason that was all that was available, a switching regulator would make more sense.

Ron:
Yes my post must have reached ET just seconds before yours (back a bit in this thread).

 

[gkn]

@reloadron::thanks sir..one more doubt!!by using this circuit all the led glows bright or not???

 

[Reloadron]

@reloadron::thanks sir..one more doubt!!by using this circuit all the led glows bright or not???

Yes, that circuit will allow for the specifications you provided of Ifwd 25 mA and Vfwd 3.5 volts. You likely will not find 60 Ohm resistors so anything close like a common 62 Ohm will be fine at 1/4 watt. Make sure you get all the LED polarities correct.

Ron

 

[gkn]

thanks sir....

 

[gkn]

validity of LED sir???and when will LED gets destroy???

 

[gkn]

i used 9V battery with 6 branches of 3 leds...totally 18 leds..drawback is led was not glowing brightly

 

[Reloadron]

i used 9V battery with 6 branches of 3 leds...totally 18 leds..drawback is led was not glowing brightly

That nice and what current was the battery rated to deliver? Were these the 3.5 volt LED you mentioned? Let's see 3.5 * 3 = what? Sure greater than 9 isn't it? Earlier I mentioned each string of 3 LEDs when powered by the correct voltage would draw 25 mA. If you have 6 strings that would be 150 mA by my math and you still do not have enough voltage. The problem here has become that you choose not to learn and would rather have someone else explain things over and over. Again 3.5 volts * 3 = 10.5 so why are you screwing around with a 9 volt battery? Additionally 9 volt battery says nothing at all, what is the battery model and how much current can it deliver. I gave you a circuit for 12 volts, I suggest you use it.

Ron

 

[gkn]

ok sir...will u please tell me when the led stop works

 

[tvtech]

ok sir...will u please tell me when the led stop works

Oh boy...all I can say is the old timers like Reloadron and others have the patience of Job (minimal) helping here
How do you guys put yourself through this all the time -- and still hang onto your sanity????

All I can say is WOW.

This thread has made me dizzy from the first post...

Very Kind regards guys,
Tv Tech.

 

[Reloadron]

In theory a LED should last forever. There is no how long. How long depends on a dozen variables including the quality of the LED. If for example you run a LED rated for Ifwd at 25 mA and you run it at 20 mA it will last longer. The entire environment figures in. Temperature, vibration and the variable list goes on. How long will it last? Till it dies. Simple huh?

Ron

Note to Self: Avoid posting to questions like this after a long difficult day at work.

 

[gkn]

pls reply me...am i irritating u by asking silly questions...

 

[Reloadron]

I have answered your questions. I also expect you to use things like Google as there is endless LED information on the Internet.

Ron

 

[gkn]

I have answered your questions. I also expect you to use things like Google as there is endless LED information on the Internet.

Ron

thank u very much sir.........

 

[audioguru]

Maybe his government blocks Google in his country.

 

[Reloadron]

Yeah, that's it!

 

[gkn]

@audioguru::y r u kidding...i confused by seeing lot of sites....