The Shop > Electronics & IC Programing
LED Help please
Divided he ad:
Huge amount cheaper ehh, ehh! I got something right :thumbup:
Basically as I see it.... Please correct me if I'm wrong.
If you increase the resistance it's like closing off a water tap. The flow becomes restricted and less water gets through so there is less to be used.
So, increase the resistance and less electrictricery is there for the LEDs to share. So they glow dimmer :zap: (this only works to an extent with LEDs though, as they're not quite like incandescent bulbs!) You may however need to find some lower mcd LEDs? This requires experimentation!!!
So personally I'd get maybe 10 soldered up and using the calculator in the above link work out the correct resistance. Then I'd increase it by 2 and see what dimming effect it has in the array. etc, etc till I had the desired effect.
Then I'd make sure my resistors were up to the job... 1/2 watt or possibly higher to handle the load/heat and then make my lights!
I made a high vis' brake light (only) for my mini using LEDs years ago (17!!) only 2 LEDs and they worked well even after I sold the car on. Constantly got told they were too bright.... And that was onlt 2 of them mounted in the numberplate light housing... Stew might like those??
Anyway,
What you could do is two circuits per light cluster using the brake switch to turn what are the running lights into brake lights when the brake is operated.
I.E. a circle within a circle, the outer one lit permanently (running lights) and becomes brighter with the inner one when the brake is pressed?
If that's the case I think I could do it? just by bypassing the resistors for the running lights at the time the brake switch is pressed, thus lighting them all brightly and returning to just running lights when the brake is released.
That'd maybe involve less LEDs and give more design possibilities?
If anyone else thinks I'm talking $%*% please help us out.... But I think this'd work :scratch: :zap:
Ralph.
Just saw Bernd's post appear.... There's more stuff to help :thumbup:
Bluechip:
Wes. Bernd
Seems to give the US spec. for vehicle lamps in Candelas here ..
http://en.wikipedia.org/wiki/Automotive_lighting#Stop_lamps_.28brake_lamps.29
Or are you aware of this, and still not sure?
Don't know of other parameters , beam divergence allowed etc ?
In UK, AFAIK. it's (DC) input power/colour. ie Brake / Indicator need to be 21W & Red/Amber respectively.
I think some BMW cars have LED's in UK. .. not sure and I've no intention of finding out, only ever had one BMW car, absolute crap .. :( not going back there ..
Ralph is on the right track, but you may need a alloy clad resistor ... you need to calculte the watts of the series Resistor.
Dave BC
Divided he ad:
--- Quote ---I think some BMW cars have LED's in UK. .. not sure and I've no intention of finding out, only ever had one BMW car, absolute crap .. :( not going back there
--- End quote ---
I know Aston Martins do.... I've got 2 rear light clusters and 2 headlights.... Don't ask me where from :ddb: but someday they're going to be one sweet set of uplighters :thumbup:
As for BMW...No comment :lol:
--- Quote ---Ralph is on the right track, but you may need a alloy clad resistor ... you need to calculte the watts of the series Resistor.
--- End quote ---
Blimey.... Wasn't expecting that! :)
Ralph.
Bernd:
Wes,
I found my notes, old as they may be, on figuring out te resistors for an LED. All you'll need to know is what the forward voltage and the amperage is of the LEDs your going to use. To find the wattage of the resistor the formula of amps X volts = watts.
Here's the notes:
Hope this helps.
Bernd
Powder Keg:
This is all helpful guys\o/ I have the array designed for the oval running/brake light I'm building. For now it will have 7 running led's and 14 brake led's. That works out to 56000MCD's and 112000MCD's It might be overkill? But I want people to see me.
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