LEDs

[jeep_bluetj]

A resistor devider used to drop 12v to 4.5v would be inefficient and offset any power savings the LED had. (i.e, all the current that goes through the resistor gets turned into heat). Better option is to recalc the current limiter resistor for the LED being used. (only one resistor)

I'd run bulbs in series, or get 12v LEDS (which often have multiple LEDs in series). A solid-state regulator to drop voltage would be too much $$$ to be worth it when you can buy 12v leds.


On the original thread, I don't like LED interior light. The color is wierd for me. But I'll never use anything but for the tail, running, etc lights.

[bobhenry]

I refuse to think this hard I grabbed 2 little kerosene mini lanterns $5.00 each modified the whick holder to hold a 1157 tail light socket $3.00 ea and purchased a set of 1157 base LED conversion tail lights $ 17.00 for the pair. wired a ground to the socket and hot to the taillight pig tail you have light. If you want to get fancy you could wire each pigtail for tail light (low) brakelight circuit ( high) or you could turn on both if you really want to put on your sunglasses.

[nikwax]

the only criticisms I've read of exterior LED lighting is that LED's can be very directional compared to incandescent. Hopefully improvements in reflectors and lenses will change this.

[toypusher]

the only criticisms I've read of exterior LED lighting is that LED's can be very directional compared to incandescent. Hopefully improvements in reflectors and lenses will change this.

You can get LED assemblies that have a certain number of diodes mounted at 90 deg to the rest.

[bobhenry]

Just decorate the inside of the tear with lots of mirrors.

Mirrors on the ceiling mirrors on the walls
Hum.... sounds like a song lyric don't it !

[Alphacarina]

A resistor devider used to drop 12v to 4.5v would be inefficient and offset any power savings the LED had. (i.e, all the current that goes through the resistor gets turned into heat). Better option is to recalc the current limiter resistor for the LED being used. (only one resistor)

Correctamundo! - The voltage divider resistors will use more juice than the LED lights . . . . maybe even more than a standard incandescent light unless you're really scientific in your selection of resistors

Most LED's run on 2 or 3 volts anyway and their current limiting resistor allows them to be run on most any DC voltage, so recalculating the limiting resistor makes lots more sense

The 'standard' resistors supplied with LED's are usually for 12 volt automotive applications and car voltage is frequently a little over 14 or so - I've never had any LED used on my cars or boats burn out in the several years I've been using them . . . . but them my voltages never go above about 14

Rather than rework everything for use with your antiquated 'converter' it would be better to either replace the converter with something which limits the output voltage, or make sure your converter is always hooked to a battery, which will do the same thing

Don

[Ken J]

Wondering - do LED's run cool - or do they get hot?

Ken J.

[jeep_bluetj]

Wondering - do LED's run cool - or do they get hot?

Ken J.

They run quite cool. When they get hot it's for a very very short period of time then they don't work anymore

[Alphacarina]

Compared to any incandescent light bulb, they don't get very warm

But you can put a running LED between your fingers and feel the heat - A larger, high powered LED may even be hot enough to be uncomfortable to hold between your fingers, but the ratio of light output to heat is much, much less than for any type of incandescent bulb

Still, I wouldn't say they run 'cool' or 'cold' - They still get warm . . . . just not nearly as hot as other bulbs

Don

[ARKPAT]

Risistors?
How about a Constaint Current Diode at the rated current level needed?
Or is cousin the the shorted gate - drain FET.

Within voltage and current ratings that is.






Pat

[brian_bp]

I wouldn't do a voltage divider, because as mentioned earlier it is inefficient, and because and the output voltage would depend on the resistance of the light. A simple single-chip voltage regulator will work to get the desired voltage, and only costs a couple of dollars.

There are no 12V LEDs, but there are arrays of LEDs connected in series and equipped with a resistor so the whole setup is suitable for use with a 12V supply. I would do that rather than adapt anything intended to run on three little batteries.

The next problem is that you really want to regulate the current, not the voltage. LED lamps routinely include that resistor is series to provide a crude form of control: if the LED allows more current than planned, the resistor drops more voltage, reducing the current through the LED. Small battery-powered lamps like the Dot-It don't need such a resistor, because the batteries themselves have high internal resistance... unlike the battery which powers the trailer lights. Again, the easy route is to use automotive lamps, such as those sold for trucks and trailers.

[bdosborn]

Here's an easy Variable Voltage Regulator:

http://ourworld.compuserve.com/homepage ... page12.htm

You can get everything you need to make it at Radio Shack. I plan to run all my LEDs off of this so they last longer. The higher voltage from my battery charger kills some LEDs pretty quickly.

Bruce

[eamarquardt]

I too want led lights and found the following site.

http://www.superbrightleds.com/other_bulbs.htm

I ordered one of their arrays and one of their landscape lights with a 45 degree beam. The lanscape light at $34 is cheaper than the yacht lights I've seen on the net and is really nicely made (machined al. and waterproof to boot). With the addition of a small base and a switch it will work very well as a reading light.

The array comes with a bulb base on it. I cut off the base and wired the array directly to 12 volts and got a one time bright flash. After closer investigation, they built a voltage regulator into the bulb base (oops and $22 down the tubes). It would be really easy to make a dome type fixture for the array.

The color of the light these leds produce is natural enough for me. Not the bluish light some produce. I plan on using the spots for reading lights and galley lights plus put a couple of them on camera tripods (picked up at garage sales (aka treasure hunts) and use them for general lighting outside. I'll use the arrays for general lighting in the cabin. I also may use a red array (maybe from an led tail light) as a dim light in the cabin to use at night so your night vision isn't destroyed and I start wandering about ouside in the middle of the night to use the head.

Hope this helps.

Cheers,

[eamarquardt]

There are several ways to get the correct voltage/current for LEDs.

Here are some sites that offer two possibilities. The first uses current limiting resistors and the second decsribles how you can configure an inexpensive three terminal voltage regulator to get whatever voltage you desire (within limits). the 78XX and LM317 regulators are good upto about an amp (from what I read). Radio shack sells the LM317 but I'm sure they can be had for less somewhere else.

http://www.theledlight.com/LED101.html

http://vancouver-webpages.com/peter/vreg.pdf

Hope this helps.

Cheers,

Gus

[love2camp]

I've tried the ones from Superbight.com and found them not to last very long. Guess they are cheap made, anyway I plan on trying some from http://www.12vLedLights.com they seem to be very reasonable priced and have a nice selection of reading lights.