Five to ten 10MM LED require what power supply?

I am planning on making a LED reading light for my nephew, but I'm not sure what kind of power supply would be needed, or how long it would last. I have bought plenty of 10mm LED's and I'm planning on using one or two per light points, with there being five light points in an 8x11 inch space. What kind of power supply would I need for these? I was thinking of going with AA batteries, since they're readily available, but I'm not sure if I'd need one or four (put into one of those cheap battery holders, I think they're setup in series.) Also, is there a way to do it without resisters, or would resisters be required, no matter what? Thanks for any assistance! The Atomic Soul

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AnthonyM2766 months ago

average LED milliamperes and voltage 5 and 10mm

5mm: V3.15 mA30

10mm: V3.3 mA30

110100101108 years ago
10mm leds are used with resistors just like any other leds. the resistors may be smaller try to find the datasheet of the leds. if you cant then your best guess is the minimal resistor with which the leds stay cool after long time being on i'd expect voltage to be same as in small leds of same color for stationary light its better to plug it in the wall than to run on batteries. you may use rechargeable batteries and charge them inside the lamp without taking out pwm (555 chip) can allow the use of smaller resistor and boost efficiency (more battery life)
TheAtomicSoul (author)  110100101108 years ago
Here's the spec sheet on the LED's I bought: http://www.abctronics.com/abcTronicsWeb_Home_E%20com%20Aviso%20de%20Fim%20de%20Ano_files/page0026.htm

I'm not sure where on there it tells that info though (I'm an electrical noob.)

If using a resistor do I still need to worry about burning through the LED by too strong a battery?

I considered using a cord but he's a very active kid, rarely sits still, and likes showing things off. :)
forward current (typical) 20 mA
forward voltage (typical) 3.15 V

the led can hold up to 30 mA current. it'll be brighter (not by 1.5 X. much less) but have shorter life

it seems that those leds are electrically same as standard small leds (not more powerful) just with big head

you need a resistor. it ensures the leds dont get too much current as long as the voltage of the battery is right (or lower). the voltage does not depend on quality of the battery

use this site to find the correct resistor for the led http://led.linear1.org/led.wiz

use rechargeable batteries and add charging diode and resistor (i'll show later how). this way the batteries are all the time in the lamp (no need to take out) and to charge you connect it to usb or wall transformer etc
TheAtomicSoul (author)  110100101108 years ago
So- wait, are you saying I was basically ripped off?!! O.o Now that you mentioned it, the rating for all their white LED's ARE the same. should I be demanding a partial refund for this? Where can I find the 10mm LED's I see people talking about in their instructables that's actually more powerful then the small ones (or these)? Thanks for the link, that'll be a big help!
you don't really need a 10mm LED Whats important is: MCD (light output, the higher the better) light angle (for most leds like 10mm and 5mm this is fairly small, which means that the beam of light will br pretty constricted) You can't really ask for a refund cause you bought what was advertised, wasn't his/her/their fault.
thats right

you said all their leds are with the same rating. this gives us a hope that the datasheet may be wrong - if they copy pasted the same datasheet for all the leds and changed only the dimensions (maybe they dont have the datasheet themselfes so they cheated)

power the led at 20 mA exactly (try to use a multimeter in series with the led to measure mA) and look at the light output and color. if it looks dim (as if the led is underpowered) then its likely that the led is more powerfull
guyfrom7up8 years ago
yep, 11010010110 has it pretty much covered