tail light components

Discussion in 'General Electronics Chat' started by caladina, May 10, 2009.

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  1. caladina

    Thread Starter New Member

    May 10, 2009
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    Hi, new here,
    couldn't see a intro page?
    anyway, i've been a panel beater and body fitter for over 20 years, the last 10 being in london black cabs so most of the new 'cool' auto stuff has passed me by in regaurds to the led tech stuff
    never done any eletronics construction before

    i'm after creating a set of led tail lights for my car (12v)
    (yeah another one)

    i'm looking to create a above average system, i have seen the 2006-8 vw passat which appears to have a red to amber colour change led system
    as of yet i havent got my hands on one of these units, there are some on the way via a breakers

    so a few q's,
    are red/amber bi colour led's available suitable for auto use?
    and are red/white bi colour available?

    the main light design will be round ring, simalar to the passat if that doesnt work out
    so a ring of 24 led's about 5 - 6 inches in diameter
    i would like to have the red side lights to turn yellow for direction and a second unit with the same 24 led's turn from red to clear for reverse light
    if the red to clear and red to amber are not available then i will probably have to use an of/on switch within the pcb to swap between colours of led's
    as i've never created or done any eletronics i need to work out what components to get
    i'm in London, UK so maplins comes to mind

    can i get what i need there or is the better stuff available else where

    so which type of led's, how many can be used in each array, what type of risistors will i need
    if there is a how to been done then obviously i apologise for reposting a samy Q, but i've not seen any red/amber leds come up in the search

    also how many ways are there to replicate the side and brake light brightnesses, risistors, buld type, different power delivery etc?

    Thanks for any help or directions

    oh ps, are there any members in the uk that can make the actual pcb for me once the bulb layout / pcb design has been done?
    of course i will pay for the work and materials, i'll be able to solder in all the componets
     
    Last edited: May 10, 2009
  2. Darren Holdstock

    Active Member

    Feb 10, 2009
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    How do.

    Your biggest problems would be meeting legal requirements for wavelength, optical power and viewing angle (tail-light LEDs are slightly special), so probably the easiest way to obtain parts is from the scrappy's. You may have to clear any such modifications with your insurance company or you could find your insurance suddenly becomes invalid.

    I must admit I don't like most LED tail lights, as I find them dazzling and distracting. It would be OK if diffused-package wide-angle LEDs were used, but I guess they're not as cheap or efficient.
     
  3. caladina

    Thread Starter New Member

    May 10, 2009
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    yep, when the led tail lights first came out i thought they were too bright and dazzling too, what i liked about the vw passat ones was the fact that the tail side lights (red uk) changed to indicators (yellow uk), pretty cool,
    as for insurance, yeah, any excuse to not pay up is worth asking,
    if i use the vw workings then they will have all the right components and leds.
    when they come i'll try getting a pic of the circuit up for ref if anyone is intrested

    would still like to know what the ideal type of bulbs, risistors and how many per array etc

    i'm hoping i'll just be able to wire them up and they work, depends i suppose if vw had other specific components to make them work, like a different type of feed from the loom, ie are the flasher units on the lamp circuit rather than a flasher control under the dash, should be fun finding out:eek:

    btw my rear panel is a bolt on one as the car is rear engine so if after it is all done they say no at the mot then i can just bolt on the old one with stock lights
     
  4. caladina

    Thread Starter New Member

    May 10, 2009
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    ok this is gonna be a reeeeeally noob Q for you guys,
    What do you in the circuit board construction call an 'or' switch?
    by this i mean the pcb component that switches from one circuit to another, ie i send a command to said component to switch from red led circuit to yellow
    does a transistor do this???????

    yeah i know a 5 year old will know it but hey, its pay back time for all the times i've helped out newbies on the bodyshop and airbrush forums

    thanks guys
     
  5. caladina

    Thread Starter New Member

    May 10, 2009
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    I got the passat rear light units yesterday, stripped them down to the circuit boards
    what a SWEEEEEEEEET unit!!!!!
    i'll try and get some pics up if anyone is intreasted? the led's are about 3 mm ceramic squares with pin prick luminating sections, the single bright (brake) reds being one hole and the red/yellow having two pin prick luminating holes (side and indicator)
    gonna call the board manufacturer and see if the do a bright red / white led :)
     
  6. Darren Holdstock

    Active Member

    Feb 10, 2009
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    Yeah, do post pics, I'm quite curious to look inside these things. I'll admit I know little of how the taillight LED circuits are actually implemented, just the range of possibilities.

    You can imagine an OR switch as two switches (A, B) wired in parallel, and turning either one on (A OR B) will energise the circuit. Likewise, an AND switch would be two switches wired in series (A AND B) so that both would have to be turned on to energise the circuit.

    The truth table of an OR gate: http://www.allaboutcircuits.com/vol_4/chpt_3/6.html
     
  7. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    You won't get red/white in single leds. Or red/amber for that matter, BUT you do commonly get red/green, which I have used many times and when both red+green are on the light looks yellow or amberish, depending how hard you turn on the green part. You can get any colour from red to amber to yellow to green based on the 2 resistors you use for the red and green leds.

    For an OR circuit in taillight use, you can just use 2 diodes. Many led taillights do this for the 2 tail/brake wires, so the taillight wire operates one bank of leds, the brake wire operates a new bank and the taillight bank too.
     
  8. caladina

    Thread Starter New Member

    May 10, 2009
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    [​IMG]

    above is the central disc which contains the single bright red led's and the outer corona ring with red / yellow bi-colour leds

    [​IMG]
    and a close up of the outer ring containing the bi-colour dim red and bright yellow leds
    the disc sits inside the corona ring behind the origonal chrome plated plastic reflectors which i have cut down to sit behind a flat panel as the origonal lamps were for a modern corner config

    when i have a bit more time i can put a yuotube vid up if you like, although they can be seen on any 2006> vw passat
     
    Last edited: May 17, 2009
  9. Darren Holdstock

    Active Member

    Feb 10, 2009
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    Interesting - thanks for the pics caladina. I would have thought that the tail lights at least would be driven by an SMPS current source, but it seems they're all using resistive droppers. I guess that's still a power saving over incandescents though.
     
  10. caladina

    Thread Starter New Member

    May 10, 2009
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    sooooo far over my head i can't even see the landing lights lol

    two things, what is the name of these type of led?
    also would it be possible to have a bi-colour bright red / bright white in this type of led?
     
  11. DonQ

    Active Member

    May 6, 2009
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    My 2 cents.

    If you dart your eyes back and forth while you are looking at LED tail-lights, you may be able to notice that they blink at a high rate. This is so that they can drive the LEDs at their peak current at a 1/4 duty cycle (for example), without exceeding a lower average current. The eye sees the peak brightness and the light appears as bright as if the LEDs were being constantly driven at the peak current. If they were constantly driven this brightly, they would burn out.

    Brighter lights, less average current, win-win.

    If you want to replicate the brightness, you will probably have to strobe them.
     
    Last edited by a moderator: Dec 27, 2013
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