Jon Ison
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 posted on 20/12/06 at 09:08 PM |
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LED lights. One for the electronic experts amongst us ?
My search for LED rear lights that I like as too date come too nothing, found one or two advertised for trailers/lorry/bus type but now really what I
want.
Whats involved in making your own ?
Say I wanted a cluster of clear LED's that within them contained stop tail and indicator functions how easy/hard is this too do ?
Please remember I'm not bad with spanners but crapo with electronics ?
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oliwb
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| posted on 20/12/06 at 09:10 PM |
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From my experience as long as you buy 12v led bulbs it shouldn't be too hard...simply a case of mounting them all and splitting them into the
sections you want eg. half tail and half stop then wire them all together in their sections and out to a relay or the switch directly....I'm no
expert but can see no reason why that shouldn't work....you might have to be carefull with regards to wattages etc as this will effect the speed
of the flash amongst other things....Oli.
If your not living life on the edge you're taking up too much room!
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snapper
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| posted on 20/12/06 at 09:15 PM |
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Just make sure you comply with the SVA lighting area rules.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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smart51
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| posted on 20/12/06 at 09:17 PM |
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12V leds are just 2V leds with a regulator of some sort. for automotive use, you should have something that will withstand 18V ro more for a short
time but still work, at least partially, below 8 or 9V. The last thing you want is to blow your lights on a dark road or have them go off when
cranking.
LEDs can be bought clear or self coloured in red, orange, yellow, green, blue and white. You can make all light functions for a car with them. They
are available in different viewing angles. The viewing angle is usually conical and usually between 15° and 45°. The brighter LEDs are brighter
because all the light is crammed into a narrow cone.
I would use a constant current source to regulate the battery voltage to drive the LEDs. I'd also check into the legality of driving the red
LEDs at 1/4 power for tail lights and full power for brake.
Do you need lenses for rear lights or is it OK if you meet the viewing angle restrictions. What about E marking. Could you cheat and hollow out an E
marked fillament lamp and stick your LEDs in it?
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Jon Ison
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| posted on 20/12/06 at 09:22 PM |
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I realise the E mark could be an issue come MOT time just wondering what was involved and if it was a diy option for a numpty like me,
just thinking out loud.
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Jon Ison
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| posted on 20/12/06 at 09:30 PM |
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The closest i have found too what I am looking for is these, they are E marked and have reflector built in.
Stop/Tail/Indicator.Image deleted by owner
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Fatgadget
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| posted on 20/12/06 at 10:53 PM |
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This circuirt can drive up to 10-15 high brightness red LEDs
Note: The transformer and bridge rectifier and "battery" are not needed!..Incidentally this circuit is for a battery charger but it works
equally well as an adjustable DC supply. 2.4V--35V
Full details can be found here
[Edited on 20/12/06 by Fatgadget]
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BenB
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| posted on 20/12/06 at 11:33 PM |
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LEDs are constant current device. As previously mentioned you need to take note of an over-voltage situation (like being jump started by the 24v of an
AA/RAC van).. Other than that it's easy...
I'd put the in series up to 18v total forward voltage then in parallel. In my experience, LEDs will take an over-current for a minute or two
before breaking down...
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RazMan
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| posted on 20/12/06 at 11:43 PM |
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The main problem with using conventional leds is that the brightest ones have a very narrow field of view and they tend to 'disappear' in
daylight. Simplest and best option imo is to use the latest Luxeon Star leds as ALL the other so-called replacement bulbs are absolute crap (and I
have tried most of them)
These little beauties are another story. I have been experimenting with diffusing lenses and have now installed them in my lights - even the reversing
lights.
One tip - if you use them in conventional light units, choose the same colour as the lense (ie red led for red lense) as the white variety gets
filtered out by a coloured lense.
As far as E marking goes, I seem to recall that the manual says it is ok to have anything fitted (no e marks) as long as it is deemed to be
effective.
[Edited on 20-12-06 by RazMan]
 
Rescued attachment 1157_3wled10.jpg
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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Confused but excited.
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| posted on 21/12/06 at 01:01 AM |
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Check out 'LED1.de' on t'web.
If using high power LEDs make sure the heatsink is adequate.
Be careful when playing, sorry, doing developement. The 5 watt type are so bright they will damage your eyes if you look directly at them when
powered! 
Tell them about the bent treacle edges!
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marvinsy
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| posted on 21/12/06 at 05:04 AM |
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this site might be of help: http://www.hidplanet.com/forums/index.php
but you first have to register look for the LED forum
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Kissy
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| posted on 21/12/06 at 06:45 AM |
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Jon, once SVA is out of the way you should have no issues with the MOT. They tend to look for functionality. I managed to MOT with r/h dip h/lamps
and a bit of tape and 'custom' motorcycle indicators with clear bulbs as side lights.
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Tricky Dave
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| posted on 21/12/06 at 09:33 AM |
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I've been thinking about this too, and with the advent of the cree xr-e led, LED headlights are also beginning to look distinctly plausible.
Check out this thread:
cree xr-e beam shots
Try the LED section of candlepower forums for people who've done similar stuff before.
LEDs do need a current regulator to work consistently, as their resistivity changes with temperature so a resistor limited circuit can not provide
constant current. The best / cheapest option I've found (building stadium power LED bicycle lights!) is the LM317 regulator (available from
Maplin). Very easy to set up and use.
What are the MoT rules, or where do I find them? There are lots of potential problems with doing headlights, but it could be very cool...
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stevebubs
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| posted on 21/12/06 at 09:52 AM |
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http://www.s-v-c.co.uk/SVCMIXMATCH.HTM
[Edited on 21/12/06 by stevebubs]
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stevebubs
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| posted on 21/12/06 at 09:54 AM |
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http://www.s-v-c.co.uk/SVCMORELIGHTS.HTM
95mm UltraBright LEDs
Stop/Tail
Amber Indicators
Rear Fog
£38 pair + £4 P&P
£45 pair + £4 P&P
£22.50 each + £4 P&P
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RazMan
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| posted on 21/12/06 at 10:56 AM |
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quote:
Originally posted by Tricky Dave
LEDs do need a current regulator to work consistently, as their resistivity changes with temperature so a resistor limited circuit can not provide
constant current. The best / cheapest option I've found (building stadium power LED bicycle lights!) is the LM317 regulator (available from
Maplin). Very easy to set up and use.
Dave, Technically you are spot on but the Luxeons appear to be more flexible in this respect. I dismantled one of the automotive 'bulb
replacements' and it just has two resistors (for dual brighness levels) & two diodes (for polarity protection)
The electronic purists will probably opt for a PWM circuit to do it properly but my experience suggests that things can be kept simple.
[Edited on 21-12-06 by RazMan]
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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02GF74
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| posted on 21/12/06 at 11:21 AM |
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quote:
Originally posted by BenB
LEDs are constant current device. As previously mentioned you need to take note of an over-voltage situation (like being jump started by the 24v of an
AA/RAC van).. Other than that it's easy...
I'd put the in series up to 18v total forward voltage then in parallel. In my experience, LEDs will take an over-current for a minute or two
before breaking down...
crap - just lots allm y typing so will be brief.
re: jump start - just turn your light off! 
re: cicuit - one resitor and 3 LEDs in series @ 20 mA should be fine; maybe a zener to clmap voltage?
I;ve had 12 V LED lamps from maplins - oil press/rad. fan on/indictaor in LAnd Rover and not blonw them so not sure if overvoltage is that a concern
but then these are no safety critical lamps.
y
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Jon Ison
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| posted on 21/12/06 at 02:31 PM |
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quote:
Originally posted by stevebubs
http://www.s-v-c.co.uk/SVCMORELIGHTS.HTM
95mm UltraBright LEDs
Stop/Tail
Amber Indicators
Rear Fog
£38 pair + £4 P&P
£45 pair + £4 P&P
£22.50 each + £4 P&P
Ive had these, not really what I'm looking for this time.
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Bob C
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| posted on 21/12/06 at 07:14 PM |
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I'd looked at these
http://docs-europe.electrocomponents.com/webdocs/032d/0900766b8032d17f.pdf
for the electric car - an array of 6 should be suitably effective for a slow vehicle + not waste too much battery!
I'd drive 'em with a current controlled switcher which would cost another couple of quid for every 2 lights. The lights are £3.60 each
from RS & they sell 2 different reflectors, a 'wide' (dip) and 'narrow' (main beam). They have to be heat sunk!
They look extremely effective in the lab - but that's no guarantee of 'on the road' effectiveness
Bob
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