LED's

[Jason B]

So I ordered all kinds of LED lights thinking I can just drop them in a form with some epoxy, solder them together and make some bitchin cool speaker, drink holders, and swim deck lights. I found out it ain't just that easy...I blew a whole bunch of them putting them straight to the 12v battery. They obviously work as witnessed by the use of a 9v battery.

My dilemma is this...what do I use to reduce the current to them from 12+volts to arounjd 9-10v so I don't fry them? I'm assuming a resistor of some sort? Does anyone have any knowledge in this area???? I'm gonna go to radio shack and see if I can get some things but those clowns don't ussually know if they're coming or going for the most part.

TIA!

[Jason B]

forgot to attach these pics

[chpthril]

No need to state the obvious here, but what the heck, you cant go straight to 12V but I don't know the easiest way to step down. I know you can get some with a simple controller.

I'd like to know also!

[buffman]

My understanding is run the connection to your existing courtesy light switch on the dash.
Which in turn already has the correct connection to the 12V batteries etc.
Make sence?

[chpthril]

I think the LED courtesy lights have the residence built into the housing and have 12v straight to them from the switch.

I will prove/disprove this later when I get a chance.

[Jason B]

I found out I bought 6v LEDs. I need to just buy 12v LED's or a 6 volt battery to power them. I may just buy the 6v battery and keep them totally seperate. The 6v LEDs are super bright and WAYYYY cheaper.

[Awake1]

Homemade LEDs

JasonB - If you really want to get technical supertex.com or Philips/Lumileds websites. They have oodles of circuit information.

Automotive headlights are using Drivers (semiconducors) like Supertex, ON semi etc provide. Some of the tail-light designs just use a simple resistor and capacitor networ to step down voltage. Doing this will make them last longer/avoid voltage spikes (your electrical system may get to 14V from the alternator).

LEDs must be wired one way - reverse them and they fry!

[buffman]

I found out I bought 6v LEDs. I need to just buy 12v LED's or a 6 volt battery to power them. I may just buy the 6v battery and keep them totally seperate. The 6v LEDs are super bright and WAYYYY cheaper.

I guess that would do it
Good luck cant wait to see pics of the finished product....

[spharis]

Here
http://led.linear1.org/led.wiz

BTW there is no 12V LED. It is a circuit with a resistor inline on it. LEDs are usually in the 3.2V range and about 20-30mA.

You can reverse an LED no problem. It will not fry, but it will not light up. It is a diode. Diodes are like little gates for electrons. In non polar wiring it simply prevents current from passing. Most AC-DC converters of old were diode packs.

If you really want to work out how to figure the proper resistor size, use ohm's law.

LEDs are super cheap. You should buy them from an electronics supplier and save a bundle. Places like superbrightleds.com have serious upcharge.

What you have in that picture are NOT 6v leds (again, no such invention other than resistor packed assemblies). They are about 3.3 volts. You have them on a 9volt battery. 9/3 = 3V so there is enough charge to light them up. You can do the 3 on a single 12V as well, but you need to add a resistor of about 120ohms to disipate the left over current as heat.

[G-MONEY]

V=IR

[Jason B]

There definitely is a difference of 12v and 6v and 3v LEDs--no doubt about it.

Here are the ones I bought:
http://cgi.ebay.com/50PCS-5mm-15000m...QQcmdZViewItem

Here are the ones I need:
http://cgi.ebay.com/20PCS-GREEN-12V-...ayphotohosting

There is no resistor on them...just longer wires. They can hook straight to the 12V battery--I have other ones I ordered before I absolutely confirmed this with--no doubts there.

You can hook them up and they work in reverse polarity--with some caveats. They worked individually on a 9v battery IF wired correctly. Hooked to a 12v battery they would not work at all. If hooked reversed to a 12v battery they smelled horrible after they fried!
Hooked to a 3v (or even 2 - 3volts totalling 6v)watch battery they worked in either polarity configuration. Go figure. Makes no sense to me.

I hooked up a chain of 3 lights, then 6, then 12 trying to drop the voltage but nothing worked with the 12v battery. Everything worked with the 3v, 6v and 9v with the goofy little quirks listed above. Scratched my head.



Spharis wrote : "You can do the 3 on a single 12V as well, but you need to add a resistor of about 120ohms to disipate the left over current as heat."

Would this add a lot of heat to the system or is it minimal. Also, would it kill the battery quicker than if I just used a 6v moto battery? Which way would be "ideal?"
I left the 3 light set up on a 9v battery over night; I want to see how long it lasts. 11 hours and still kicking strong for the 3 light set!!!

[Jason B]

When I get this figured out, and it warms up enough for epoxy to cure in my garage, I'm gonna make a flat, clear epoxy plate filled with a boatload (pardon the pun ) of LED lights to litter the water with green light. I'm also gonna put them in the back of the grill arms(for lack of a better word--arms?) of my WS 650's and under the cup holders in the boat and then around the WS sub enclosure I've yet to make. I'll post up pics as I go along but I doubt it will be any time real soon. It's about 30 degrees in my garage now, and I can't afford to turn the heater on for 12 hours with gas prices the way they are

[spharis]

There is a resistor in that long wire beneath the shrink. There are no 12 or 6 volt LEDs.
http://led.linear1.org/myth-of-the-5-volt-led/

You can make them work in reverse polarity by adding a few diodes in a cross to force the current to change if connected backward, or just to protect from reverse voltage. Voltage correction (rectification) is usually done on an A/C circuit.

There is not much heat at all. If you use the wiring wizard link I sent you, it will also recommend the proper rating of resistor (1/4W, 1/2W, etc) to prevent the resistor from smoking. You should ALWAYS use a resistor. Think of it as a conditioner.

The frist link you sent

Forward Voltage (V) : 3.2 ~ 3.8

This is why the three work on the 9volt battery.


I have wired and converted more LED applications than I care to talk about. The reverse voltage isn't something you should even consider using or figuring on. The way an LED works in a nutshell is that there are two plates that are coated in a current sensitive polarized goo. When current is applied the goo gets excited across the plate to the other and gives off light as a byproduct. It happens in reverse as well, but takes much more voltage and much more life of the LED.

Another important LED spec is maximum reverse voltage. A diode conducts current when a forward voltage is applied, but will not conduct if a reverse voltage is applied, up to a point. Reverse voltages in excess of the maximum can cause the diode to fail.

Read up on the link I sent you. There is a ton of LED info there.

[Jason B]

goin to radio shack now

[Jason B]

So I went to Radio Shack to get resistors per Spharis' advice (thanks )

and WOLLA!!! Worked like a champ.

1/2 watt resistor on the 1&2 light arrays and 1/4 watt resistors on the 3+light arrays.

I mounted them loosely into a speaker to plan my install and it looks SWEET, it's gonna be sick.
I'll post pics tomorrow--wife is hollerin to go watch a movie w/ her now