I like both ideas very much but, what does the backside of the door handle look like?
How long before you knock one of the LEDs loose from opening the door all of the time?

 

Well, it depends on which windscreen you're talking about. Several people made simple versions in the past that glowed red, or white, or some simple combination. I'm the one who made the user-selectable color version, so you can have pretty much any color of the rainbow and change it on a whim, turns red with the brake, etc. In fact, I posted last night in one of the threads about lighting windscreens...the pics in the first post weren't mine, but the rest are.

I've spent so much time working on my projects I don't even have a proper website to point people to, just my personal homepage. My latest has been the footwell lights.

I haven't describe the footwells anywhere on here, so this thread is as good a place as any. No more need for glass tubes, high-voltage transformers, single colors, etc...just go with my new LED footwell lights. Color is easily adjustable with a 5-way hat switch (up, down, left, right, and press), and several options are selectable. For example, you could have the footwells turn on/off instantly with the door, OR you could have them come on instantly with a door opening and slowly fade out after several seconds of the door being closed. The S has maplights (I'm assuming the Z does, too), so you can hook them up to the maplights...with the right option selected, only the specific footwell will come on with the respective maplight (i.e., turn the passenger-side maplight on, the passenger-side footwell comes on, too).

I'm having a blast coming up with this stuff, but I get some of my slickest ideas from comments made by you guys, the users. If people are interested in this stuff, I'll try to keep you posted. The fotwell lights should go into production in 2-3 weeks (need to get the code up and running now that the hardware is finished).

/\/\ac

 

yes, series is when the negative of one LED is on the positive of the next. current is introduced into the series only once.

 

yep that's the windscreen i'm talking about. i spent alot of time over at s2ki before deciding on a 350 so i remember following those threads hard. =) awesome stuff.

 

thanks ares... thats what i thought. what's the deal with mcd and viewing angle? i'd imagine the higher the mcd number the brighter the led's are?

how does viewing angle affect things though. for instance, why would i choose a viewing angle of 15 over 30, and vice versa?

 

well basicly an LED with 5000MCD at 30degrees is the same output as a 10,000MCD at 15degrees. its a measure of light output at a certain distance, not that the second one is more light overall, its just the same light in half of the viewing area(more concetrated)

of course Im sure this is more of a theoretical than absolute, but general idea is there.

 

gotcha... thanks. gonna look into this strut bar thing =)

 

i was just doing some calculations and ares i wonder how you said you can typically wire 7 led's in series. using some info off superbright led's... let's say the led has the following values:

forward voltage = 3.4
working mA = 20
now let's say our supply voltage is 14.4

using the above calculations (and checking them with a calculator i found online) i can only figure out how to wire 4 of these led's together. 4 led's wired in series with the above numbers would require a resistor value of 40 ohms and power dissipation of 0.016 watts. accoring to calculations... adding 5 led's will make these numbers negative thus meaning too many led's.

what am i missing here?

 

Based upon the current definition defined in 1979, the official definition for Candela is:

"The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540 teraHertz and that has a radiant intensity in that direction of 1/683 watt per steradian."

Confusing as all get out, no? Let me try and break it down for you. 540 teraHertz corresponds to a wavelength of 556 nanometers, or right around the green area (while I haven't found any information to back this up, my educated guess is this frequency was chosen because the human eye is most sensitive to green light). So, when you see a measure of X mcd (milliCandelas) on an LED spec sheet, what they are trying to say is "We measure a certain brightness of green light when we look at a specific portion of the LED." This is why you can't necessarily say a red LED rated at 10,000 mcd is brighter than a green LED rated at 5,000 mcd.

But there's a downside that should start to rear its ugly head in your mind...if they're measuring the brightness of green light, how do they get a figure for red LEDs, blue LEDs, etc.? Well, LEDs aren't perfect...they tend to shine light over a wide range of frequencies. A red LED may shine at 100% in red, but also give you 5% of a green glow, as well. So, if a red LED is rated for 1 cd (which we now know is measured for green light output), you can bet what shines out as red is going to be really bright.

Viewing angle comes next. the measurement is over steredians, which basically means measuring the light output over some distance AND area. For a viewing angle of 30 degrees, they're saying "If we look straight down at the LED and measure all light that comes out of it from +/- 15 degrees, we measure X Candelas." As that angle increases, you'll see a higher Candela value, but it will be diminishing returns (i.e., you might see 10% more light if you increase the angle 5 degrees, but only 12% if you increase it 10 degrees, 12.4% for 15 degrees, etc.)

In the real world, though, viewing angle is not a hard concept to see (no pun intended). When you see the blue LEDs alarm manufacturers love to use nowadays, do you ever notice how it gets REALLY bright once you start to look almost directly at it? You can get within inches of it, but be to the side of the LED, and have no problem...but angle your face to look straight on to the LED and you'll be seeing spots for a few seconds. THAT'S what viewing angle is all about...some light will be visible from the side, but most is concentrated into a small cone.

It depends on the type of project I'm working on, but a prime example is the footwell lights. I want the light to cover a large area, but still be directable. The LEDs I use have, for all intents and puposes, a 180 degree viewing angle. If you face one of these things foward and look at the floor, you'll see a fairly sharp line of light and darkness. since I tend to work with them in the darkness during testing, I have temporarily blinded myself on ocassion by accidentally looking into their path....NOT something I suggest

I know, it's a really technical discussion, but if you understand 1/10th of what I've said we're all a lot better off.

 

Your calculations are correct, based upon the info given, so don't think you're wrong.

There are a couple of possibilities here:
1) The forward voltage of the LEDs are not 3.4V. If they're red, green, yellow, etc., they're more than likely less than 2.0V each.
2) You can use 7 LEDs, but they won't all be in series. You could have 3 in series and 4 in series, each series string in parallel.

Now, this brings up a good point about series/parallel combinations. You shouldn't put string of LEDs in parallel unless their forward voltage drops are equal (even two LEDs from the same batch may differ by a few tenths of a volt, so be careful). As the number of LEDs in a series string increase, the law of averages tends to help you out (one LED is 0.1V lower than average, and another may be 0.1V higher, so they average out).

Several strings CAN be placed in parallel, even if they have a different forward voltage drop along each, as long as EACH string has a separate resistor, like this:

+---R---L---L---L---L---L---G
+---R---L---L---L---G

each resistor will have a different value (assuming both strings are to carry the same current).

 

yeah sorry, the 7 LEDs is only for 2volt LEDs(amber red type) but white and blue take the higher amount3-3.5 ussually, in which case as you said, only 4 in a series.

 

wow .. thanks a million for all of the info... makes things MUCH clearer now. Last thing i'm hoping you could help out with...

say i wanted to connect two series of led's to an existing wire in the vehicle (let's say the + wire to the tail lights). using your example above

+---R---L---L---L---L---L---G
+---R---L---L---L---L---G

Can both series of led's be connected to the same wire already in the vehicle?

 

I personally have had problems with the parralels of different number of LEDs, if you can get the exact resistor then your fine, but often youll get them at radioshack or something, which has only certain amounts. and then you end up with slightly more current to one series than the other, meaning different brightness's. its preferable if you can make the 2 series the same LEDs and the same resistor to keep them the same.

if you go to a electronic store and get exact resistors, its not a problem.

 

yes, as long as they each take their own course from positive to negative, doesnt matter if its the same positive.

 

thanks for all the help guys...

 

Since resistances add in series, you can always trim to a specific value by adding in a small value resistor to match up the brightness. For example, if you really need a 50 ohm, but they only have 39 and 56, buy the 39 ohm and add in a couple of 5 ohm resistors. Radio Shack pretty much sells 5% resistors exclusively, so even if you were to find a 50 ohm resistor, it may actually be 45-55 ohms...it's just not that critical.

Another method is to replace the "empty" LED hole in a string with a simple diode. If you absolutely need that 2.1V drop that a red LED would provide, but you're short 1 LED in the string, put in a few 0.7V diodes to make up the difference. no light, but you get the drop, and the resistor value can stay the same.

And there's no shame in putting in the extra LED itself, but hide it from view or wrap it in electrical tape. Not the most cost-effective solution, especially for $2-$3 white and blue LEDs, but it's certainly a workable one.

 

For those interested in the footwell lights, here's a pic of the controller board out of the box and the two LED strings...



I placed the penny there for size reference. the white strip between the 2 LEDs on each string is there for flexibility. You can point each LED in whatever direction you want...wrap it around a pole and aim them in opposite directions, twist them to light up the floor and sidewall, or aim them both in the same direction for an even brighter light.

I didn't take a pic of the other side with the hat switch since it's not installed on this prototype yet (I want to play with other portions of the code first).

Feel free to ask any questions...

 

The door handles that have LED's in them have been covered with a vinyl material so they will not affect the LED's in them as pictured here , as well here is some other areas they are in

 

Here is one that is inside the air vent

 

If you wire all the LED's in parallel, with a single in line resistor, brightness will be the same

+---L----R---G
|---L--|
|---L--|
|---L--|
|---L--|
|---L--|
|---L--|

More wires though...

Can someone post a link to a site that sells theses LEDs?