r/electronics • u/poincare101 • Mar 24 '12
Quick USB Hack
Hi!
I got 50 LEDs off eBay last night and felt like I had to hack something together.
And, here came the LED light! Check it out:
http://imgur.com/jStlq,uExPh#0 http://imgur.com/jStlq,uExPh#1
Also: https://gumroad.com/links/HuNtu
I use it to fish about behind my desktop, because I can't see much without it. And, the flexible wire is really cool for moving it around in the darkness.
Tell me what you think!
UPDATE: http://imgur.com/9T7Dw (electrical tape added).
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u/Enlightenment777 Mar 24 '12
Hey everyone...I hooked up LEDs to power sources back in the mid 1970s ... oh my .... amazing ... wow !!!
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u/poincare101 Mar 25 '12
I never said it was anything amazing; I just thought it was cool how it ran off USB and on a flexible wire.
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u/Enlightenment777 Mar 25 '12
I agree it is cool and most people forget that USB is a cheap 5V-ish DC power source. You can also do the same thing with PS/2 mice/keyboard cables, because PS/2 has a power pin. You can also do it with RS232 cables, but it takes more components. Prior to those things, the easiest source of power was cutting off the ends of wall-warts.
I was stacking sarcastic crap on you and the up-voters because of the obviousness of it, so don't let that set you back from experimenting and having fun.
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u/TheMagnificentChrome Mar 25 '12
I know this technically qualifies as electronics but fuck me man, this shit is toddler level electronics.
Also "hack", people keep using that word...
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u/oskay Evil Mad Scientist Laboratories Mar 24 '12
I've done this with a 1 W LED. Makes a pretty good little reading lamp.
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u/CaptKrag Mar 24 '12
Did you add a series resistor to limit current or is that unnecessary for some reason? Not too familiar with usb power
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u/N4N4KI Mar 24 '12
the images here http://imgur.com/jStlq,uExPh#0 http://imgur.com/jStlq,uExPh#1 looks like he has a resistor
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Mar 24 '12
[deleted]
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u/poincare101 Mar 24 '12
I used an old iPod cable. Huh, I wonder where the downvote came from.
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Mar 24 '12
[deleted]
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u/poincare101 Mar 24 '12
I did, with some electrical tape. I'l upload new images.
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u/digitalundernet Mar 24 '12
Get LOTS of shrink tube. Its cheap and lasts a lot longer than tape. Usually when I get out the electrical tape its fine for a few months then turns into a sticky mess.
EDIT: I just saw you ordered some. Ignore this.
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u/singlehopper Mar 24 '12
Any USB 2.0 compliant hub has short circuit protection.
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Mar 24 '12
[deleted]
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u/singlehopper Mar 24 '12 edited Mar 25 '12
To quote the USB 2.0 spec:
A USB transceiver is required to withstand a continuous short circuit of D+ and/or D- to VBUS, GND, other data line, or the cable shield at the connector, for a minimum of 24 hours without degradation. It is recommended that transceivers be designed so as to withstand such short circuits indefinitely.
A reverse plug in would result in whatever you plugged in seeing -5V. Usually that's a semiconductor killer. Low impedance path through a body diode or something. Should have resulted in the port just disabling power.
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Mar 25 '12
[deleted]
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u/singlehopper Mar 25 '12
Must not have properly implemented the USB spec, then. Shame on them for slapping a USB logo on it.
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u/SSChicken Mar 24 '12
Get some heat shrink tubing and cover everything up from the bare usb cable to the LED! It will look much nicer, and you won't have to worry about it snagging on things.