9v LED Do-it-Yourself project

Images don't work :o(

> Resistors are used to reduce the vehicles 12 v down to whats required for the led's

They can be, yes, but, following a lightweight/efficiency ethos, you're better off using a switching regulator to drop the voltage to something much closer to the diode forward voltage, and using a much smaller resistor. This will give better efficiency (less power lost in the resistor), thus prolonging battery life.

The alternative is to use a current-controlled driver instead, and regulate the forward current.

There are dozens of suitable circuits from the likes of Maxim that will do just this. Google 'LED driver'.

It might be worth looking at white sidelights, since they're moving to LEDs these days, too. A potentially cheap source of high-power white LEDs.

The pictures work okay if you copy & paste the obvious URL from the fubar'ed links.

I've made quite a pile of little LED lights.

I live off grid and my home is wired for 12 VDC. At first we used 12vdc fixtures but when 5mm white LEDs became available I started making home-made fixtures.
I have one neighbor on this mountain and naturally he is also off grid. He has been making LED fixtures for his home for a long time. Back in the day before white LEDs he used several different colors mixed in the same unit to sorta-almost approximate white light, and he has made piles of small LED lights and solar power units to light parks department out houses and boat launches at various camp grounds ( anyone ever ben to hawk creek campground on lake Roosevelt? ).

Anyway, for small units I just use bright 5mm white LEDs. I've purchased them in bulk from here –

http://www.lck-led.com/index.php

And from radio shack for smaller projects. A very nice light for off grid cabin or car can be made by mounting six 5mm LEDs in a standard handy box cover. A toggle switch can be mounted on the side. Powered by 12vdc they make excellent reading lights by your bed or the like.

I once made a pile of such lights powered by two 9 volt batteries contained inside the handy box, and sold 'em at a gun show. They would burn a very long time indeed on those two batteries.

And of course, I've made a pocket flashlight by cutting the top off of an old 9 volt battery and mounting two 5 mm LEDs on it along with a small switch and two resistors, and potted the whole thing in epoxy. Snaps on top of a 9 volt battery, rather like the commercial "pack lights. Lots of fun!

Anyway, if anyone is interested in tinkering, this site will help you figure out your resistor circuits and is otherwise an excellent resource. –

http://led.linear1.org/led.wiz

Theses days my home is lit by white LED strip lights, with one remaining compact 12 vdc fluorescent fixture. I can light my entire cottage at about an amp and a half!

Edit – Yes, there are other ways to drive LEDs than resistor networks, but when you figure in the added cost, complexity and the tiny amount of electricity saved, I don't find it worth the bother.

Dan's project is an example of how to get the job done with little expense. Others have suggested methods to get it done with the greatest electrical efficiency and with much greater expense. Each backpacker just has to decide what priorities come first.

Part of the problem with a DIY LED housing is that you end up with lots of little sharp edges and soldered joints. You can pot the whole thing in epoxy, but then that weighs a little.

It is very difficult to beat the perfection of a Pak-Lite. It works with a single 9V battery, no wires, Hi-Lo settings, and two LEDs for the light emitters.

–B.G.–

6-8 months passed after I first showed how I made the little emergency LED in this photo and then the Pak-Lite came onto the market. Parallel ideas? I shoulda went commercial with it;-)

I first introduced the design on http://www.survival.com forums many years ago. The LED’s were first being seen available on ebay. Radio Shack had the wire harness for the batteries. The little black plastic battery cap is necessary for storing the battery safely. I used shrink tubing to cover the wiring. No resistor was used. I had Lithium batteries stored with the LED’s and after 5 years they were still holding a charge.

In the photo you can see a plastic baggie filled with magnesium fillings with 4 wires protruding. Those wires are connected to model rocket engine ignitors. Good for starting emergency fires in the most wet environments.

I also dabbbled in making a flashlight using Tritium tubes that had a light life expectancy of 15 years. I take the light out of it’s case once in while and the tubes are still producing light. The tubes were salvaged from emergency “exit” signs. What? it’s the “curiosity” in me LOL.

Tritium Flashlight at bplite.com

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