Dutton Kit Cars and their owners

I moved this off Paul's thread as well, it just seemed to be the polite thing to do...

The discussion regarding lighting may go on for a bit.

I've been using LED technology since the late 80's for various things. Special effect, model making, domestic lighting and of course car lights. I've experimented on three or four of my vehicles with varying degrees of success. LED's work best in an environment designed to suit them. Trying to fit a shallow angle led into something designed to accept a tungsten filament bulb is awkward.

CMV is all LED apart from thee headlight bulbs and the reversing lights. I've had about 8 different styles of indicator bulb trying to find one with an adequate light output. The ones I have fitted at the moment are the best I've had but they worked out at about £5 a pair compared to 80p for a tungsten one. 

I'd like to try and explain howto pick the right design of LED for the intended application and how each type differs.

Lets look at a normal light bulb  . These normally have a 'base' bayonet which fits into a socket. That socket doesn't need any light pumping into it as it it then wasted energy. So, the base is ideally a dark spot. Works with both types of bulb, tungsten and LED. The opposite end is 'normally' the bit that faces the outside world so chucking energy at it works for both bulb types - all good upto now?

Tungsten filaments work by passing electricity through a bit of wire and making it glow white hot, the hotter it gets the more intense the light. If this is trapped inside a glass case with an inert gas such as xenon it can get VERY hot and therefore will produce a good amount of light. As the glass case is transparent that light can escape in any direction which is why car light units have reflectors to spread the emitted light out and throw it in one direction. LED's however have a very narrow field of view. The 'filament' is actually two bare ends inside a tiny pocket of Gallium Arsenide... a pocket the size of a pinhead... when you look into an LED you can sometimes see one side is a cup shape and the other is a sparkplug shape electrode, the gas between the two electrodes reacts when charged to give off light, the chemical composition of the gas can be varied to produce different colour light. So when compared to a normal tungsten bulb the LED is way more efficient however due to the small size of the element the light output is smaller and concentrated into a beam by the small cup shaped reflector. The small cup shaped reflector also means the 98% of the light is thrown in one direction in a narrow beam. 

Views: 265

Reply to This

Replies to This Discussion

Are we talking about the same thing here Ade?  One of these ..... 2200w Cree chips.

link to source, country of origin? certainly looks like it would replace an H4.

2200W is stage lighting level, totally unsuitable for vehicular use. You'll be damaging the retinas of everyone coming the other way Paul.. oh yeah, like all RangeRoiver, Audi, Merc, BMW drivers....

One of the guys over on Kitnet has just put some in a Fury.


oooops......... that was suposed to say;   2200 lumens with Cree chips

They're good, so good they've sold out. Its the first one I've seen that looks correctly aligned.

Maybe some thing for you to source and sell through the shop, I will buy some from you, and do a fitting and testing article.  

These are the ones in the fury,

I'll have a shop around to see if any of my suppliers can get them. Certainly looks like they will do the job but i'm not sure about putting a bulb with a cooling fan inside an enclosed headlight bowl.

Still reading... good.

The above means that LED's have very little light output sideways which means putting them in a reflector environment means the reflector has nothing to reflect - wasted material.

Recently I switched to a new design of LED called a COB or chip on board LED. This is comprised of many small LED elements on one board with no reflector. It actually looks like a little yellow or white circuit board, normally with a soft rubbery surface.

To make use of a standard light setup with a reflector I have found that this type of setup works best.

This type can spread the light around inside the reflector element which means it replicates the energy emissions of a tungsten bulb. With one part of the element facing the coloured lamp surface there may be a 'spot' in the centre of the lamp if the unit is too close. The general light output is as good or better than tungsten, the response time is faster and the energy consumed is 1/7th (approx). This is fine for indicator, reverse and fog applications. The dual element bulb for stop and tail however has not yet been tested. The last ones I tried caused the centre brake light do come on dimly with the sidelights :(

Stick around and I'll do another on instrument lights and sidelights (501's) theyre fun too :)

thanks for that ade :-)

While your at it, I would appreciate thoughts on projector headlights, thinking about them on the B+ , when the new carbon fibre bonnet and cycle wings finally arrive.

I've looked at various alternatives but the mainline aftermarket manufacturers like Ring and Hella seem reluctant to switch (no pun intended) to LED. There are quite a few on amazon with 5 star ratings though. I'm going to make enquiries with some of our wholesalers and see what is available.


© 2024   Created by Tim Walker (The Bodger).   Powered by

Report an Issue  |  Terms of Service