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Discussion Starter #1
1st - tried the STUPID replacement LED bulbs (1157 / 1156)
not even close to bright enough

2nd - tore apart a 2000-2005 Cadilac Deville tail light
bright enough (68 LED's equilivant to a 55watt bulb)
but the shape isn't very easy to mold into my housings

3rd - I order 1500 LED's and 12 LED circuit boards.
I'm going to build my own, and blind people behind me :D
I'll find out if buying the LED specific boards was worth the cost

Bulk LED's: http://ledshoppe.com/
72 LED circuit boards: https://dalewheat.com/order.php (called: BIGGER IR Spotlight, PCB)
 

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Keep us posted Fire, I too have been working some LED projects, but have yet to find something that is satisfactory. The only thing I can figure is 1W or 3W Lexun LEDs, which are $Pricey$!
 

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That's weird that you wrote that. I have been doing research today for a LED taillight project on my Cobra. What I can't figure out is how to dim thim for tail operation and then return them to full brightness for brake/turn. Have you figured something out?
 

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derrick36 said:
These are the one's I was thinking about.(scroll down the the light tower IIs)
http://autolumination.com/1156_1157.htm

They're spendy, but I thought with LEDs it was worth it.

You prolly just saved me $40+:thumbup
I got a LOT of LED replacment bulbs from eBay, autolumination, premiertek, and the parts store.
They all worked, but had less light than the normal bulbs.
badblack88 said:
That's weird that you wrote that. I have been doing research today for a LED taillight project on my Cobra. What I can't figure out is how to dim thim for tail operation and then return them to full brightness for brake/turn. Have you figured something out?
You need diodes and an extra resistor for a dim tail light.
 

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That makes sense, but some of the places that I looked suggested that leds don't dim like an incandescent. They said that to dim them you basically turn them on and off at a very rapid rate, something like 75Hz or so where the led is perceived to just be dimmer by our slower brain. I know that the oem lights on some cars do that. If you sweep your vision past them (hard to explain) you can see them blinking when they are in "tail" mode. Kinda like you can see the refresh rate of a monitor if it is in your peripheral vision. Savvy?
 

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Just rig it to where only half (like a checker pattern) light for "dim"
 

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If you wanted to take the time to wire it all in you could even do cool patterns like alternate lines. sides, blocks, or a kewl swirl.
 

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I already have lots of those "replacemnt" LED bulbs
All trash in my opinion

I'm building a complete panel to go inside the housing.
 

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Here is some info
Main page http://members.misty.com/don/ledx.html

basic info page http://members.misty.com/don/ledd.html



This document is in early stages of construction as of 7/16/99.

Back up to my LED main page.

Most LEDs have their characteristics specified at a current of 20 mA. If you want really good reliability and you are not certain you don't have worse-than-average heat conductivity in your mounting, heat buildup in wherever you mount them, voltage/current variations, etc. then design for 15 milliamps.

Now for how to make 15 milliamps flow through the LED:

First you need to know the LED voltage drop. It is safe enough to assume 1.7 volts for non-high-brightness red, 1.9 volts for high-brightness, high-efficiency and low-current red, and 2 volts for orange and yellow, and 2.1 volts for green. Assume 3.4 volts for bright white, bright non-yellowish green, and most blue types. Assume 4.6 volts for 430 nM bright blue types such as Everbright and Radio Shack. Design for 12 milliamps for the 3.4 volt types and 10 milliamps for the 430 nM blue.

Those 2.6 and 2.8 volt figures for many green, yellow, orange and some red LEDs are not typical voltage but some maximum during production sample testing, above which they are considered defective. Typical voltage is 2 volts for red and orange, 2.1 volts for yellow and 2.2 volts for green if you see a 2.6 or 2.8 volt figure.

You can design for higher current if you are adventurous or you know you will have a good lack of heat buildup. In such a case, design for 25 mA for the types with voltage near 2 volts, 18 mA for the 3.4 volt types, and 15 mA for the 430 nM blue.

Meet or exceed the maximum rated current of the LED only under favorable conditions of lack of heat buildup. Some LED current ratings assume some really favorable test conditions - such as being surrounded by air no warmer than 25 degrees Celsius and some decent thermal conduction from where the leads are mounted. Running the LED at specified laboratory conditions used for maximum current rating will make it lose half its light output after rated life expectancy (20,000 to 100,000 hours) - optimistically! You can use somewhat higher currents if you heat-sink the leads and/or can tolerate much shorter life expectancy.

Next, know your supply voltage. It should be well above the LED voltage for reliable, stable LED operation. Use at least 3 volts for the lower voltage types, 4.5 volts for the 3.4 volt types, and 6 volts for the 430 nM blue.

The voltage in most cars is 14 volts while the alternator is successfully charging the battery. A well-charged 12 volt lead-acid battery is 12.6 volts with a light load discharging it. Many "wall wart" DC power supplies provide much higher voltage than specified (often 10% above nominal or half a volt above nominal, whichever is higher, and maybe more) if the load is light, so you need to measure them with a light load that draws maybe 10-20 milliamps.

The next step is to divide the dropped voltage by the LED current to get the value of the dropping resistor. If you divide volts by amps, you get the resistor value in ohms. If you divide volts by milliamps, you get the resistor value in kilo-ohms or k.

Example: 6 volt supply, 3.4 volt LED, 12 milliamps. Subtract the 3.4 volt LED voltage from the 6 volt supply voltage to get a difference (which is across the "dropping resistor") of 2.6 volts. Divide 2.6 by .012. This gives 217 ohms. The nearest standard resistor value is 220 ohms.

If you want to operate the 3.4 volt LED from a 6 volt power supply at the LED's "typical" current of 20 mA, then 2.6 divided by .02 yields a resistor value of 130 ohms. The next higher popular standard value is 150 ohms.

If you want to run a typical 3.4 volt LED from a 6 volt supply at its maximum rated current of 30 mA, then divide 2.6 by .03. This indicates 87 ohms. The next higher popular standard resistor value is 100 ohms. Please beware that I consider the 30 mA rating for 3.4-3.5 volt LEDs to be optimistic.

One more thing to do is to check the resistor wattage. Multiply the dropped voltage by the LED current to get the wattage being dissipated in the resistor. Example: 2.6 volts times .03 amp (30 milliamps) is .078 watt. For good reliability, I recommend not exceeding 60 percent of the wattage rating of the resistor. A 1/4 watt resistor can easily handle .078 watt. In case you need a more powerful resistor, there are 1/2 watt resistors widely available in the popular values.

You can put LEDs in series with only one resistor for the whole series string. Add up the voltages of all the LEDs in the series string. This should not exceed 80 percent of the supply voltage if you want good stability and predictable current consumption. The dropped voltage will then be the supply voltage minus the total voltage of the LEDs in the series string.

Do not put LEDs in parallel with each other. Although this usually works, it is not reliable. LEDs become more conductive as they warm up, which may lead to unstable current distribution through paralleled LEDs. LEDs in parallel need their own individual dropping resistors. Series strings can be paralleled if each string has its own dropping resistor.
 

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I got the PC Boards, and they are nice.
If you have a few bucks, they are worth it.

3.75" X 2.00"
 

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Ryan,
Take a look at these guys too, I've had their flush mount lights in the back fender of my Harley for about 4 years. They make them in dual brightness, different sizes, amber & red. The flush mounts could easliy be worked into a stock lamp housing and save you the grief of wiring up a board of LED's.
http://www.hitechledproducts.com/index.php
 

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how are you guys liking the pop in 4" round led trailer style lights? anybody adapted those? seems simple, cheap and effective, thinking about a set for my trailer....
 
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