 | Home > Technical > Resistors to reduce LED lights? |
 
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| Bluest Member Since: 23 Apr 2016 Location: Lancashire Posts: 4217   
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I don’t think you can dim LED with resistors. They don’t work like filament lamps. 2007 110 TDCi Station Wagon XS
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4th May 2023 6:28am |
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| swt Member Since: 24 Aug 2018 Location: Cumbria Posts: 163 
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Dimming circuitry for LEDs works by turning the current off an on more quickly than the eye can detect, if I recall correctly. You can get little 12v, adjustable, dimmer units for use with LEDs. I have one on some additional dash lighting. Google "12v LED dimmer".
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4th May 2023 6:50am |
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| TexasRover Member Since: 24 Nov 2022 Location: Paris Posts: 1086  
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So if your normal running rear (red) lights are too bright, how bright is the brake light?
..and who told you this? Personally I would not be messing with the circuitry of the car. Probably cheaper to buy new lights, but it would be interesting to find out why these lights are too bright, I am mean they are being sold so.. |
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4th May 2023 7:40am |
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| Ianh Member Since: 17 Sep 2018 Location: Essex Posts: 2036
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If your lights are E marked, and they need to be to be used on the roads in the EU and UK, then they have been certified as conformant and therefore can’t be too bright.
You need to look at the lens to see if an E mark is present , contact Bearmach to confirm they are certified, ask for a copy of the certification and present that certification to the body that is stating they are too bright. If not certified Bearmach should not be selling them for EU and UK road use. Here is some useful info on E mark certification of vehicle lights. https://www.ogaled.com/why-do-we-need-e-mark-approved-lights.html |
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4th May 2023 10:43am |
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| o4dn Member Since: 08 Jan 2010 Location: South West Posts: 545 
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Yeah, they are E marked, but… they are too bright.
The regulations specify 5W lamps for use with the side and tail lights, and the LEDs replacement look way brighter than a 5W bulb lamp, so much brighter that it dazzles the other drivers I've been told. As for Bearmach, I think they went belly up. “A Land Rover immobilized is a moral defeat for the driver and bad publicity for the vehicle, […] it's up to you to do justice to your Land Rover!” - Land Rover Driving Technique. -- 2009 2.4 Puma Defender 90 SW 1979 Land Rover Series 3 88" |
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4th May 2023 12:03pm |
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| Ianh Member Since: 17 Sep 2018 Location: Essex Posts: 2036
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Dohh .. I forgot they went out of business.
Mine are wipac , have had no issues with people saying they are too bright, and you can get a set of wipac LED tail/stop lights for circa £33 on line so I think that would be the easiest way to go. |
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4th May 2023 12:30pm |
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| Ashbyandy Member Since: 17 Dec 2015 Location: Leicestershire Posts: 223  
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od4n,
Don’t have a go at me for asking, but I assume you have wired the tail and stop light wiring the correct way round, ie brighter illumination when you hit the brakes 👍,, Andy |
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4th May 2023 12:36pm |
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| o4dn Member Since: 08 Jan 2010 Location: South West Posts: 545
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Andy, yup, the break lights are indeed even brighter! But anyhow, the econoseal connectors are foolproof
 “A Land Rover immobilized is a moral defeat for the driver and bad publicity for the vehicle, […] it's up to you to do justice to your Land Rover!” - Land Rover Driving Technique.
-- 2009 2.4 Puma Defender 90 SW 1979 Land Rover Series 3 88" |
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4th May 2023 1:27pm |
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| o4dn Member Since: 08 Jan 2010 Location: South West Posts: 545
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There was a similar thread on here a few years ago, and people reckoned the Wipac are indeed less bright than the Bearmach ones, so it's not just me!
 “A Land Rover immobilized is a moral defeat for the driver and bad publicity for the vehicle, […] it's up to you to do justice to your Land Rover!” - Land Rover Driving Technique.
-- 2009 2.4 Puma Defender 90 SW 1979 Land Rover Series 3 88" |
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4th May 2023 1:29pm |
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| TexasRover Member Since: 24 Nov 2022 Location: Paris Posts: 1086
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Unless some regulatory body would tell me otherwise (and since they have an E-mark) I would personally not change anything. Do you really care about what people behind you or otherwise think?
Anyhow nowadays with more and more automatic cars every other car is sitting a the lights 'dazzling' the person behind them with their brake lights. When I got my license - a long time ago - I was told to use the handbrake for exactly that reason. I suppose today we don't need to care that much about the people behind us. |
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4th May 2023 1:42pm |
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| o4dn Member Since: 08 Jan 2010 Location: South West Posts: 545
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TexasRover, yeah, I don't disagree here… “A Land Rover immobilized is a moral defeat for the driver and bad publicity for the vehicle, […] it's up to you to do justice to your Land Rover!” - Land Rover Driving Technique.
-- 2009 2.4 Puma Defender 90 SW 1979 Land Rover Series 3 88" |
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4th May 2023 1:54pm |
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| sako243 Member Since: 08 Jul 2014 Location: Wales Posts: 1225  
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Not complete b******* but not correct information. LEDs are current mode devices - they drop a fixed voltage across them (dependent upon colour), their brightness is dictated by current. You can limit current by fitting a resistor inline with the LED, unrestricted current can actually wear them out prematurely in some circumstances. The other way is to PWM (pulse width modulate) the power going to it which chops the supply on and off such that it averages a lower current thus dimming it. If your switching frequence is above 30Hz then the human eye struggles to see the flickering (hence why most video is coded to 30fps) so you don't actually need to do any smoothing. The reason PWM is preferred to a simple resistor is that it's more efficient particularly at the more powerful end of LEDs. It's also more versatile and easier to control. So to the OP yes a suitable resistor will dim the bulbs. Ed 82 Hotspur Sandringham 6x6 95 Defender 110 300Tdi |
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4th May 2023 5:01pm |
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| Dinnu Member Since: 24 Dec 2019 Location: Lija Posts: 3425  
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100% agree with Sako above. LEDs are current driven, and a resistor in series is an easy way to reduce current flow. Just note that you would need a resistor with enough power dissipation, so that the resistor does not become too hot and either go open circuit or short out. 1988 90 Hard Top, 19J Diesel Turbo, Shire Blue - Restoration ongoing
2012 90 CSW, 2.2TDCI, Santorini Black |
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4th May 2023 5:29pm |
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