Modest improvement to a harbor freight led flashlight by Tool Using Animal
I picked up a sweet little 9 led light from HF for $5 and it was kinda flaky, shake it and the light went out, so I'd thought I'd post my improvement.
 
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Step 1: What's the problem

The positive connection is a spring loaded pin pushing against a blob of solder. High resistance and just poor contact.
electfire says: May 10, 2012. 3:44 PM
I used the LED module in one of my projects. Unfortunately the one LED flashlight I had the LED side didn't unscrew... so I have to at it with pliers... which was surprisingly easy...I think these are made out of cheap (thin) aluminum.
chrisbaker says: Oct 20, 2010. 6:53 PM
In case anyone is wondering, these are made slightly different now: the bodies no longer unscrew at the light end (only the button end) and there is now a spring soldered directly to the contacts on the circuit board where the LED's are attached. The battery holder only has metal contact tabs at each end. There's also a spring attached to the button end (don't know if this is a change). You must have inspired them, Tool Using Animal!
moosetooth says: Sep 24, 2011. 5:30 PM
I have several of this type that quit working. The circuit board that the leds are on are pretty inaccessible so other than scratch the contact with a pen knife I can't do much with it. It's a shame cuz I really liked them when they worked.
tinkerinaround says: Nov 28, 2008. 1:04 AM
Advance Auto parts has these flashlights for $2 each. Test them all b4 buying, some have good(bright) LEDs, some don't. Try adding hot glue to the LED side of the board for shock protection. I've scavenged the push button switch from several of these.
thelightoflinux says: Sep 16, 2008. 10:47 AM
I just bought two of these at Big Lots. They came in a two pack for seven bucks. One of them is kinda crappy, but the other works pretty .I'm gonna try this on my bad one later.
grayelf says: Jan 23, 2008. 9:27 PM
Got a light like this for free...hardly worked at all. Battery insertion diagram on interior was actually wrong. Loose parts, but I never could figure out what was wrong. My circuit board was also different from the one pictured here. Actually burned a good sized blister into my finger from the current heating up the spring...got pissed and gave it to a friend. He got it working and thinks it is great.
Yerboogieman says: Dec 7, 2007. 11:19 PM
plus so durable and stuff but the guts dont look the same
Yerboogieman says: Dec 7, 2007. 11:18 PM
i liked mine so much and it lasted so long bought 9 of them
calculusrunner says: Jan 3, 2007. 8:18 PM
I have this same flashlight that I got from www.fifthunit.com a few weeks ago. They had a special for 2/$5 with free shipping. The site has some surprisingly high quality flashlights from China and such (you still get what you pay for, but its on the higher end of the cheapos). Mine had a spring at the top as well so I don't have this problem, but it looks like the solder might break loose so I'll have to keep this in mind.
unjust says: Nov 28, 2006. 3:54 PM
good hack. now lets see it with a few high output leds swapped in ;) (i'm actually workign on that, but having time issues atm)
GadgetmanKen says: Nov 27, 2006. 8:50 PM
Oh, and I originally wanted the ones like that in camo but they were sold out. Got a rain check, tho.
GadgetmanKen says: Nov 27, 2006. 8:46 PM
I have one of those too, with the same problem. I thought it was the contact spring at the bottom, because it was flimsy. But, I tried the nut thing with no results. After close examination, I noticed my circuit board was different than yous a little. The circuit board in mine just had an outer ring on the circuit board for I guess the ground and all the positive ends were wired to the center glob via the leads. And after closer examination I noticed that a couple of the ground side leads were a tad bit longer than the others. Maybe a couple cm. So I bent them over. Couldn't find my side cuts. DooH! Anyway when I screwed the hex grounding ring back in, I think I screwed it tighter than it was, but now does not flicker or shut off. Don't know if the longer leads were not making good contact or the hex ground ring. Nothing worse than a flashlight that won't stay on, or flicker. Its a great BRIGHT little flashlight. oh, and inexpensive too. I'm getting several more.
meddler says: Nov 24, 2006. 12:30 PM
Good idea, i bought a small light like this from an army surplus store and it doesen't work at all, maby this is the reason? Of corse it doesen't matter anymore since i threw it away....
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