LED Light conversions

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LED Light conversions

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Martin

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No I don't mean a flippin Lexus conversion before anybody jumps on their soapbox ;)

On my Motorbike I have converted the rear light unit to LED's. I made it myself, it's not the bulbs you buy that are actually LED's.
My LED unit is basically a piece of Vero board that fits inside the lens of the rear unit.
Then I have made 2 seperate LED clusters, amde up of 4 rows of 5 LEDs. Each row of 5 LED's are in series and there is a resistor to limit the current flow and also to dim the LED's so that they look like tail lamp brightness. Then there is another resistor that gets dropped in parallel when the brake is applied that increases the current.
I did this for safety really, I have seen so many bikers riding with one of their bulbs blown, and to be honest how many of us check our rear lights? LED's have a very long lifetime and are very very resistant to vibrations unlike a filament bulb.
I was wondering about doing this to my Bravo, trouble is I would have to make 6 units as each rear light is made up of 3 segments with a bulb in each. Also I am unsure if I could get into the reflector area of the unit, anybod know if the rear light unit comes apart?

One other thing I have done is replaced the lights in my dash unit on the bike to LED's, the reason I did this was because it's a complete pain in the arse to replaces the bulbs if one blows. I started with Blue LED's (yes LAX power I know) and it looked fairly good but Blue LED's are very ver directional in their beam pattern so I could only see a very small part of each dial, even in total darkness. I then took sandpaper to the leds to diffuse the light, and it made the light spread much better, but it was far too dim for use, so I doubled up on the LED's and again it is too dim. So I changed to red ones and they a hella brught and illuminate the dials really well. Well recommended a change to LED lighting for dashboards.
I did it myself, not the real expensive ones that are sold on Ebay.
You need a 470 ohm resistor in series on the +ve leg to limit the current to a single blue or red LED, on the red LEd's they runa lower voltage, so I put 2 LED's in series. I am unsure if this would work well on a car as the wiring on the rear of a dash is normall on a flexible PCB. I guess if you could find the illumination +ve feed in the loom on the multiplug you got put a resistor on that. Not really recommended to run multiple LED's in parallel off one resistor though (a lot of head scratching going on here ;) )

Just thought I'd let you know of my gadgettery !!!

One other thing with LED's as a brake light is they are near enough instantaneous illuminated once the brake pedal is pressed. You don't have to wait for the filament to warm up. You can see this really well on cars that have normal brake lights, but with a LED third brake light.

I do hope you enjoyed this trip on my waffle bus !!!
 
Instead of using veroboard, why not mke yourself a PCB?

You can get a free PCB design package thats easy to use from www.cadsoft.de
and when you have finished your layout, you can send it to
www.pcbpool.com
who will make a relatively cheap but very high quality PCB for you. Ideal if you want several circuits the same - PCBs are much easier to test/assemble than vero, and wont corrode over time.

With LEDs you can choose their efficiency esp red leds. Leds are also available with different beam angles or indeed diffusion, so there is a wide choice!

Careful with your current limiting resistor, as this will dissipate power and get warm. If you try and take too much current through a resistor of the wrong wattage you will burn it out. Its easy to work out the power dissipated for a given current. If its too high you can consider putting smaller value resistors in series to spread the load.
Hope that helps

Nick
 
Re: Re: LED Light conversions

Nick,

Thanks for that, I have been looking for a good, simple free PCB design program, this looks good, I am playing with it now :)
I would much prefer to creat PCB's as I wan't a circular design rather than the current rectangular design I have.

I realise the limitations of LED's and current limiting resistors ( to a degree ;) )
 
Re: Re: Re: LED Light conversions

I've used Eagle quite a bit, very good bit of software. Be warned, some of the PCB decals are a bit dodgey.

As for LEDs, all the different colours have different forward voltage drops so the best way to wire them changes.

For blues and whites with a 3v forward drop you ideally want to put 3 of them in series with a 270 ohm resistor. This minimises the power disipation of the resistor. Anyone who says you should put them in parallel with 1 resistor is talking crap. :)

Reds tend to drop about 2v so you could get 4 in series.

You just gotta find some cheap LEDs :)
 
Re: Re: Re: LED Light conversions

Must admit, it sounds really cool... is there likely to be a problem getting the modded LED bank through your MOT, do you know?
 
Re: Re: Re: Re: LED Light conversions

Not really, it must be bright enough and have even light. Not hard to achieve unless you are truly useless :)
 
Re: Re: Re: Re: Re: LED Light conversions

I'll post pics of my effort sometime. The LED brake light is pretty bright. When I am on a dark road and I brake signs behind me by about 400 yds are brightly illuminated by my brake light :)
I am also gonna build 2 smaller units for fitting in the top box for my bike as well :)

The trouble with LED's is they are produced really cheaply and as such the quality of each LED is different, they will all draw a slightly different current. That is why they should not be run in parallel. You can kill LED's I have killed about 6 in my experimentations, they go into a thermal runaway type thang and burn out :(

The way my rear light is set up is 4 identical rows of 5 LED's in series running off a 470 and 220 ohm resistor in series for the 'normal' tail light. Then a 150 ohm resistor is dropped inbetween the last resistor and the first LED to increase the current.
I am not a very good electronics whizz, this schema was given to me and does seem to work quite well.
As I said I would like to create a circular PCB to make it look more professional.

My first play with Eagle is O.k but when I convert it to a PCB it looks pants, any tips? Can I customise the way the PCB looks and reroute the tracks?

There are numerous providers of LED's I have been using Ebay to get most of mine. I bought 40 Ultra bright red LED's and all the resistors for the light unit for £16 including P&P.

The ebay link for the guy I have used is:

http://cgi6.ebay.co.uk/ws/eBayISAPI.dll?ViewSellersOtherItems&userid=ligfries&include=0&since=-1&sort=3&rows=50

He is really helpful, if you email him with a certain requirement he will work out a price. A nice guy :)

I have also built a little white LED torch for my daughter, I made it with 9 white LED's in 3 banks of 3 running in series, connected to a 9v battery, I didn't use a resistor cos the LED's actually need 9.9 volts so I assumed they didn't need a resistor. Please advise if this is incorrect.
 
Seems like a lot of effort to me.
Why not just buy the LED bulbs which are commercially available? I've seen 'em, not sure where.

Mark.
 
Re: Re: LED Light conversions

Cos the bravo uses some odd sizes and cos the ones that are normal sized have to be inserted from the back and all the LED bulbs are too big. :(

If it was a normal light cluster where you took the lens off to replace the bulbs it would be easy.
 
Re: Re: Re: Re: Re: Re: LED Light conversions

To get the schematic into a proper PCB, you have to position the components in a sensible position inside the board outline. The you have to route the tracks. The mess of yellow lines you are probably seeing is called the ratsnest and just shows which point needs to connect to which other point. Its up to you to route them yourself in a sensible way. There is an autorouter tool but for this complexity you are better routing it manually. You can set the width of the tracks at the time of routing.

It is possible to import DXF files as the outline, so if you have a complex board shape, you draw it in some drawing package, export it as a DXF then use one of the free utilities available from the Cadsoft website to convert into a PCB layout. Its a bit of a pain but can be done!

Nick
 
Re: Re: Re: LED Light conversions

I started this LED mullarky maily because I got fed up taking the fairing apart on my bike to replace a blown bulb in the dash unit. The LED bulbs for this are well expensive, anything from a fiver a pair, whereas a single LED is less than a pound.
After doing my dash I had the LED bug then, so I looked into doing the rear light, now 2 LED bulbs for the stop/tail are £25 eek.
A little time and effort on my part and £16 has built a reasonable unit for my bike :)

Looks like it will be a little harder with a car light unit, as Tom says you really need to be able to take the lens off from the front.
 

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