Led usb emergency bulb from dead bulb.

snakebite

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Mar 17, 2001
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dayton oh
Wordless
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workshop style.
 

Dave_H

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Nov 3, 2009
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Ottawa Ont. Canada
I've opened up a few dead LED ac bulbs plus several which were not dead to check what's inside. There may be tricks to breaking off a glass bulb cleanly, but better if the bulb is plastic; fine hacksaw works right at the bulb base.

Increasingly, dual/triple LEDs (maybe even quads) in series are being used, especially for stacking voltages up to 130v or so to work with linear controllers. At least one such bulb from Dollar Tree in Canada is like this. Those LEDs won't work directly with USB 5v. Of course you could replace LED(s) with one(s) known to be single die, and could rig more than one in parallel.

Dave
 

snakebite

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Mar 17, 2001
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dayton oh
Thats a nichia 219c thermal glued to the emitter mcpcb.
I ground down to the aluminum.
That is a "great value" walmart bulb.
I put on grippy gloves and pulled the dome off without damage.
Super long usb cable so i went with 2 ohm resistor.
You can use whatever hits your current/brightness target.
When reasembling lay a bead of thermal adhesive in the step of the heatsink.
Press in the mcpcb then pop on the dome.
At 5.1v it pulls 780ma.
Led is 280 lumens at 700ma.
So around 300lm - losses in the dome.
A few drops of ca at the wire entry will strain relieve it.
 

Poppy

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Dec 20, 2012
Messages
8,396
Location
Northern New Jersey
Thats a nichia 219c thermal glued to the emitter mcpcb.
I ground down to the aluminum.
That is a "great value" walmart bulb.
I put on grippy gloves and pulled the dome off without damage.
Super long usb cable so i went with 2 ohm resistor.
You can use whatever hits your current/brightness target.
When reasembling lay a bead of thermal adhesive in the step of the heatsink.
Press in the mcpcb then pop on the dome.
At 5.1v it pulls 780ma.
Led is 280 lumens at 700ma.
So around 300lm - losses in the dome.
A few drops of ca at the wire entry will strain relieve it.
Its FUN tinkering around like that.
:clap:👍
 

PhotonWrangler

Flashaholic
Joined
Oct 19, 2003
Messages
14,450
Location
In a handbasket
Thats a nichia 219c thermal glued to the emitter mcpcb.
I ground down to the aluminum.
That is a "great value" walmart bulb.
I put on grippy gloves and pulled the dome off without damage.
Super long usb cable so i went with 2 ohm resistor.
You can use whatever hits your current/brightness target.
When reasembling lay a bead of thermal adhesive in the step of the heatsink.
Press in the mcpcb then pop on the dome.
At 5.1v it pulls 780ma.
Led is 280 lumens at 700ma.
So around 300lm - losses in the dome.
A few drops of ca at the wire entry will strain relieve it.
That's a nice bit of MacGyvering there.
 

snakebite

Flashlight Enthusiast
Joined
Mar 17, 2001
Messages
2,725
Location
dayton oh
A neighbor and I made up 12 for emergency kits.
He found a bunch of NOS 20' usb printer cables.
I am sure thats out of usb spec but as usual adjust resistor value to hit current target.
And lots of the cheap led bulbs die as often as incans so getting the word out to save them gets you plenty.
They barely get warm reassembled to get the thermal path to the funnel.
Likely last forever.
Now who even remembers wordless workshop?
 
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