anyone ever mess with led's?

[Master ACiD]

ive never really been a electronics geek but i bought a 50 pack of white led's on ebay for a little over $10 shipped from hongkong. ive been having fun today making my own lights out of spare walwarts, etc.

these things are incerdible. i put 9 in my flashlight and its been on for over 12 hours now and hasnt dropped its brightness.

the thing right now i am working on is a a/c led light. i got a full wave bridge diode out of a junk television, used it with a 60uf 200v capacitor to boost the 120V mains to 170V, then add a very long string of led's in series to the output of the diode bridge.
ive got it mostly done but my fingers and neck are killing me, so i took a break and came online.

 

[Master ACiD]

you guys are going to laugh but heres the result of my work. its REALLY ghetto.

theres 170V unshielded.

maybe i should quit while im ahead (maybe im already behind?)

 

[moribundman]

Let us know when ET replies to your signals, Edison.

 

[Pablo]

I thought you guys had good weather down there?

 

[oilyriser]

http://en.wikipedia.org/wiki/Current_source

This will help prevent thermal runaway.

 

[Sparkman]

A non-impedance-limited bridge connected to mains can be deadly, but you probably already knew that.

The cap doesn't really increase the voltage, nor does the bridge. The AC waveform has the +- ~170V (~120 * 2^0.5) peaks in it already, the bridge makes them all the same direction, and the cap takes the droop out between peaks. The ripple current can create a fair amount of heat in the ESR of the cap. Many engineers will derate a caps voltage rating by 50%, and they make a VERY big bang.

Generally I wouldn't recommend what you are doing to people unless they have a high tolerance for excitement. Fairly dangerous and unforgiving. I wouldn't be playing with those voltages without some insulation on things, a relatively small fuse, and probably a GFCI.

 

[mechtech2]

Sparkman - How about wiring an LED in automotive [12V DC] circuits? Are resistors necessary? Is there a big current draw?
What is proper?

 

[moribundman]

Basic LED resistor rule:

R=(Actual Voltage - LED voltage required)/(current in milliamps)*1000

Let's take a typical white LED 5 mm LED (4V, 20 mA):

R=(12V-4V)/(20ma)*1000=400 Ohm

Maximum Voltage and consumption vary, depending on LED type. Today, you can buy LEDs that are made for 12 Volt sources -- they do not require an additional resistor.

I installed a number of accessories with switches with LEDs in them in my first car back in the fading days of mullet hair. Off the top of my head (no mullet!) I recall using 330 Ohm resistors for red LEDs and 220 Ohm for green LEDs. Back then blue LEDs were ultra-rare and white ones were not yet on the market. Now we got LEDs that consist of three LEDs and that can change color -- wheeeeee!

 

[ALS]

Here you go. There is an article in the latest issue of Rolling. Rolling is the Volvo Club of America's magazine for members. Here is a link to a story on building LED units for automotive use. LED uses in automobiles

 

[Master ACiD]

safety safety safety wel all love safety.
its a ghetto system for sure, but i left it on all last nite and it wasa still working this morning. i had to of done something right. my kill-o-watt metre register basically nothing.
anyways i know that its not the safest thing around, but this is just expierments. the final version will be enclosed with a little fuse and a heatsink on the rectifier and everyone will be safe again.

 

[Oldmoparguy1]

Would be interesting if you could measure the lumens.

 

[moribundman]

Simply buy a handheld lightmeter that can display lumen, candela, lux, etc.

 

[Master ACiD]

heres the final product. it uses 3 watts (tested with kill-a-watt metre) and if i trust the led manf to be honest about the light output of these led's then ive got the equivalent of a 35watt filement bulb.
the final construction consisted of nearly 40 led's glued to old cd's stacked together and glued to a broken filement bulb base. a full wave bridge rectifier is in the middle along with the capacitor.
i handmade that rectifier by the way. no $2.00 pre made radioshack units for me!

ive got this bulb installed in a stained glass ceiling light fixture.
this first pic is with the flash off and the contrast adjusted to hightlight the fixture.

next pic is of the actual finished bulb glowing.

this is a pic of the bottom of the finished bulb

and heres the top

yeah i know the pictures suck. whatever. my normal digicam is broke and im using a cheap polariod backup.

 

[farrarfan1]

I have a Federal lightbar and a rear window deck full of em on my 2007 CVPI. But I don't think that's what you meant...