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I have a reading lamp that I use at night that has a standard 15w bulb in it. I was wondering if I could use a group of around 20-30 ultra bright leds to make a 'lightbulb' that would work instead of the regular bulb.

The modification might not be very cost effective. I spent time on a project that used a low voltage transformer with good results. You do have a practical idea for those leds. I have also seen some interesting automotive interior lighting designs.

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>The modification might not be very cost effective. <hr></blockquote><p>
Yeah I would agree with that. But you could get the led's from here.

I just got done meeting with a rep today. Check out these super cool LED's. 1000 lumens!!! or thousands of lumens.
http://www.laminaceramics.com/products.html<p>Certainly overkill for a reading lamp, perhaps even for a car headlight, but most interesting.<p>Ron

ONE will do! I have a blue LED that blinds your eyes, to look into it. It hurts! <p> The white ones I bought recently, I believe are 10,000 mcl, even Brighter than the blue one. <p>With the blue one you can read a book at 10 feet away, in the absolute dark.

To begin...My interest here is using LED's to build 12V lamps for the house.<p>I am not an electronics expert and I wanted to know how I would design a 12V circuit that would use 3.6 - 4.0 VDC to build a lamp?<p>Cost effectiveness is not an issue when it comes to RE, Watts, Volts and AMPs savings are my reasons for wanting to pursue this.<p>Cheers

it would take lots of leds to make any feasable light brighter than a night light...even with the traffic light leds i work with here...they use about 400+ leds in a unit...its good source of light, but doesn't give much else...
so cost wise..you'd be better off with compaq flourescents...they do make 12 volt flourescent lights.... www.thinlight.com i think is one source
and also look at solar suppliers.. good luck

Reading lamps only need to shine a few feet, four to five will completely fill the need that the 15 watt bulb already does. <p>One will allow you to read in complete comfort.

My Streamlight Dual Task brand flashlight is abundant light for reading or looking for a needle in a haystack...one switch position give 3 pwripheral blue-white led's of no glare light for close work and turn it off and turn it on again and a central Xenon bulb is energized which is like a lightning bolt of briteness-I've shot a hundred feet of attic with it. $35.00 2 3-volt lithiums
last forever<p>Yodar

if they want to make it more cost-effective, the companies need to make 120VAC operated untrabright LEDs. then there is no transformer and rectifier and caps.

This is a 20 LED 120 volt bulb HERE

I have a large button, solar cell powered calculator that runs from the light given off by a 100W incandescent pantograph arm desk lamp. (very handy for doing the bills, useless if that area isn't very well lit) Would the 'quality' of the light from the $59.99, 110VAC LED 'takes 4 watts and lasts for ever bulb" power a solar cell calculator?

About three years ago I had a similar problem in that I wanted reading lights, but I wanted them to work from 12VDC. I had installed three large solar panels to charge my 12V 450AH batteries. The battery bank is used to run my amateur radio equipment. Early on I discovered that the batteries were charged, generally before noon, so I considered ways to increase the load on the batteries. One way was lighting at night.<p>I found some light fixtures that are used in RV's. They normally came with a #1156 12v bulb. I noticed that the bulb was not frosted so the lamp seemed to have a glare. I found that I could replace the #1156 with a #1141F, the F meaning frosted. With the plastic lens and the reflector of the fixture the light is great for reading. I went on step further. Realizing that the cold resistance of the bulb is lower than the hot resistance I new the life of the bulbs would be affected by initial surge current, so I built into each fixture a automatic surge circuit that limited the initial current to about what the normal lamp current is. The present bulbs were installed about 3 years ago, and they are still working. They are used every night I am home.
The wattage is about 18 watts (12.5V X 1.4A).
I am sure the same fixture would work on 12V AC for those that want to go that way.