LED VAC powered Lamp

[Zambini]

I want to learn how to make some sort of LED lamp. I will probably need (aka: I do need) an AC=>DC converter. But I want to learn what I need to make something. Much like the Koncept LEDs. They are way cool and I want to make one instead of pay $10,000,000 for one (any lamp over 50 bucks is way expensive for me).

Soooo...... I tried googling for like 5 seconds,

Without getting into a detailed circuit design, there are a couple things to think about when using an AC source. Diodes will conduct only when forward biased, so with AC driving them, they’ll be dark half the time. That isn’t generally a desirable situation, so most people prefer to rectify the AC. A full-wave bridge rectifier is an inexpensive way to effectively double the brightness. Make sure your rectifier’s peak inverse voltage is larger than the supply peak voltage. The rectifier will cause about a Volt and a half reduction in your supply, so consider that.

and this
Convince yourself to just use a 12V-to-AC-line inverter for LED light strings instead of rewiring them for 12V. - Instructables

which is very close to what I need....i think.

I am really hoping to take a class in college that pertains to this knowledge, but I would like some learnin's on it as early as possible.



So basically what I need to know/learn is this:
-How to build a lamp (lightweight)
I haven't done much building in my life. Unfortunately, I did not take that welding class my friend took @ the local CC, nor did I take woodshop. I'm sure google can help me with this part.

-How to get the 120vAC into something that LEDs can use
I think fry's carries some sort of AC=>DC converter. But what am I looking for?

-How to ensure the LEDs don't explode (or die, or that I don't die)
So I would need a heavy duty (1W or more) resistor, and then use that formula (good ol' Ohm's Law)

-Anything I missed

-Things to know before I even attempt this

[gvblake22]

You can get AC to 12V DC converters off of lots of things. Usually they come as wall chargers for different electronic devices like an mp3 player or CD players or USB hubs or external drive enclosures, etc. Don't have time to hunt one down on the internet, but I may actually have one myself I might consider just sending to you if you want (I gotta think about it though).

Twizted is the one you're gonna want to talk to about making an LED lamp, he made one himself and is a wiz at wiring LEDs...

[Zambini]

But 12V would only get me 4 LEDs.
I'm gonna need 20 or 30 of em. (either from dragonmodz or some less-awesome dealer. Hopefully from Dmodz, the ~3.3v 18k MCD ones)
(correct me if I'm wrong in my airport fueled calculations)
Which means I'm gonna need 37 of em (37 x 3.3v =122v) and a high wattage resistor.

But if you have one of those I'd gladly pay you for one, as long as it isn't way expensive.

[gvblake22]

OH, well I don't have any giant AC to DC converters like I think you are talking about. I'm not the most electrically savvy person, but can't you wire the LED's in parallel and not loose voltage along the string of LED's?

[Zambini]

K, well as usual, his holyness of LED twizted is helping me :)

I dont think I linked him to this post.... lol.

But he linked me to his doing of this also:
Desklamp Mod


So I think I have to wait till I get back home and maybe go to Fry's or look through my garage and see what I've got. (lamp wise)

The only hard part, from what I've gathered, is getting the rectifier.

I have no idea what I'm looking for there.
But..... maybe this is what I need?

FRYS.com*|*I.C'S/ Passives/ Discretes
RECTIFIER
I.C'S/ Passives/ Discretes:
FRYS.com #: 1980785
RECTIFIER. 600V, 40A. NTE-5994.

Ok, maybe not a
2.4 kiloWatt rectifier....lol

But... Radio Shack has a bajillion and I have no idea what to look for.
RadioShack.com Search for "rectifier"

Am I just looking for one that operates in the voltage range I need?


6A, 200V Full-Wave Bridge Rectifiers
Since I'm going to be working with less than that, that should do, right?
and then put a fat heat sink on it.

[Twizted]

Or you could just make your own using cheap general purpus diodes such as 1N4004. Basically all those large package deals your lookin at (much larger than you need or want in your lamp) are just 4 diodes linked together and illustrated on WiKiPedia

Diode bridge - Wikipedia, the free encyclopedia

When the input connected at the left corner of the diamond is positive with respect to the one connected at the right hand corner, current flows to the right along the upper colored path to the output, and returns to the input supply via the lower one.



When the right hand corner is positive relative to the left hand corner, current flows along the upper colored path and returns to the supply via the lower colored path.



This combined with a few other components, namely some large Capacitors, I nicked mine from a old UPS :)

Here is a circuit designs to get you started...

WHITE LED NIGHT LIGHT - Circuits designed by David A. Johnson, P.E.

Of course this design above could use far more LED's as its only using approx 80mA of the available 1000mA (1A).

Speaking of more LED's.... you would not need 122v to power 37.... I would only do 36 so you dont have an lone LED's using large resistors. You would simple make several series clusters in parallel... such as this (diagram created using LED series parallel array wizard)



Its really not that hard and can actually be setup on Project board such as we sell on DragonModz

I used project board for my Lamp mod instead of making a circuit board to speed the process up but you can make your own board if you like.... :)

Hope this has been helpful...
.
.

[Zambini]

Originally Posted by Twizted

Speaking of more LED's.... you would not need 122v to power 37.... I would only do 36 so you dont have an lone LED's using large resistors. You would simple make several series clusters in parallel... such as this (diagram created using LED series parallel array wizard)

<big image that doesn't need to be shown 2 times :P>

Its really not that hard and can actually be setup on Project board such as we sell on DragonModz

I used project board for my Lamp mod instead of making a circuit board to speed the process up but you can make your own board if you like.... :)

Hope this has been helpful...
.
.

I think for me, it'd be easier and safer to just buy one. They are mega cheap, and garanteed to work.

BUT that series idea = genious. and that diagram = makes it easy.
I just need to find a lamp and then input my own stuff into that equation.

And I've already got one of them project boards =) its sitting in my envelope, which is acting container for all my stuff from you guys.


One Question: How should I mount it? just hot glue + mass amounts of electrical tapes?


PS: is there a way I can order the LEDs and have it garanteed to be there on the 17th (Monday). I've got a very small window of heavy packing and shopping to get this thing done, meaning, 11:30 PM -> 3:00 AM every day between the 17th and 20th of sept.

[Twizted]

to have it there right on the 17th or before? I can try to mail it on a day that, providing nothing happens in route, it would arrive on the 17th exactly.. but if you ordered say, today... It would be there by Saturday (Sept 1st) or the following monday (Sept 3rd)...

[Zambini]

Originally Posted by Twizted

to have it there right on the 17th or before? I can try to mail it on a day that, providing nothing happens in route, it would arrive on the 17th exactly.. but if you ordered say, today... It would be there by Saturday (Sept 1st) or the following monday (Sept 3rd)...

Well I'm not gonna be home till Sept 17th.
And I forgot what we were doing with our mail.

[edit] Just asked my dad and he said we put a stop on it (P.O. holds it till we come get it) so yea, I'll order it whenever and then it'll be nice n safe at the post office till then :P


Maybe I can get Radioshack to ship a rectifier to me also.
This one?
Or This one?
I don't really know.

[Zambini]

Ok, well I'm gonna order 36 of [5mm-Wht-18K], the $ is cleared Sept 5th, hopefully I can order it before I go on my Iberian trip. where I wont have internets till Sept 14th.

So..... stockpile them for me :P