nasty gurl

Hi everyone. I was just wondering if there is a very simple circuit that I can make in order to have fog/driving lights on my car always on (when the ignition is turned on) but a low intensity and then have a switch that allows me to turn them on full beam when needed in reduged visibility/fog etc. Is this possible? Can someone please help me out here.

Thank you very much

tansis

Can u tell us the wattage of the lamps please, this will help to find a suitable circuit for your needs.

seeker

Hi nasty gurl,
There are two simple circuits you can build to control your fog lights.
Do you want it fully automatic (as in starts at dim on motor start then goes to bright when you push a button) or switches from bright to off to dim manually?

Thanks, Tony

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nasty gurl

Hi thanks for your help. tansis the wattage will probably be 55w and seeker, I just found out that your first option (which I wanted) is illegal so the second option would be great. Thank you very much for your help. I am fine with doing the electrics, just not designing them. Thanks

tansis

This might be usefull....
http://www.electronics-tutorials.com...ght-dimmer.htm

Attached Images

555-light-dimmer-fig1.gif (3.2 KB, 249 views)

Ocelaris

What kind of Power Mosfet can you use? I tried a circuit similar to that with a Tip31?

http://www.electro-tech-online.com/e...chematics.html

I am in another thread, asking basically the same question, I'll repost it here how I am approaching it with limited success... Please feel free to ignore, but I didn't want people to have to repeat themselves, or if someone else missed this thread like I did... :-/

Ok, I have tried this circuit, and it doesn't quite work as expected... Basically I have 8x 350mA capable LEDs 2 sets in parallel of 4 in series... I THINK... I am not sure exactly the load... But I'm trying to get 2 sets of brightnesses for my tail lights. And they're not exactly working how I expected.

First pic is the full brightness, it should be 640mA by the calculation of the lm317 which I am using, which is R = v/A so 1.2/.64 = 1.875 = ~1.9hm:

If each LED can take 320mA I think 640mA is correct, but I'm not sure if how I wired them is really 2 parallel strings of 4 in series. This is just the way I had to mount them based on my thermal and space contraints... pics to follow of my rationale.



Am I really getting 320mA to each LED? I'm a bit confused on the parallel, but I think I am?

Second I intended to run them at 2 different brightnesses, basically 320mA and ADD another 320mA diode isolated of course... but just adding two constant current sources together to get 640mA. It doesn't really work that way, it gets barely if any brighter. This is how I had that wired:



Now I was thinking it was possible that the two chips were not functioning properly, crossing each other out or something, so I tried just 1 LM317 with two 3.9hm: resistors in parallel to get my 1.9hm: but connecting and disconnecting that 2nd 3.9hm: resistor which SHOULD have netted me 1.9 ohms just didn't do anything at all... so I'm confused. I thought you can parallel resistors to get R1+R2/2 ?

Since I didn't get "half" of the brightness, I Thought maybe it was a non-linear brightness for power, but according to the SunLED Apollo PDF, this chart shows that I really should be getting about 1/2 the brightness for half the current through these LEDs...



So what am I doing wrong? Thanks for all the help. Bill

Ocelaris

55watts of LEDs is REALLY REALLY REALLY bright and/or heat. I have 8, ~3/4watt each LEDs and I have a CPU heatsink w/fan running on it. Remember LEDs aren't that efficient. So thermal management is going to be your biggest challenge, not the dual brightness...

Here's a nice little chart I found:



Even the Lumiled K2s are only 40-50 lumens per watt... and to equal a 55watt regular halogen Foglight (I assume that is where you got your 55watt number) you would be at 1375 lumens / 40 lumens/watt LED = 34 watts of High power LED...

at minimum with the impossible to mount SunLED Apollo PLCC-4 LEDs, you are going to be looking at a chunk of aluminum like 12" x 12" plus at 3$ a pop, 102$ for JUST the LEDs... If you went with the K2 which are electrically isolated, hence easy to mount on a heatsink, you are looking at 9$ a pop... x 34 = wayyyyy too $$$$ I think.

Maybe you need to scale down the ambition of 55watts of LED lighting? I'm a lighting fanatic on HIDplanet if you hadn't noticed...

Hero999

What's wrong with using a compact fluroescent tube if you want such a high power light? It will use 1/4 of the power of all those LEDs.

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Ocelaris

It's on a car, so you'd have to make an inverter. and it's not a point source of light. I think she's trying to make fog lights out of a high color temperature light source "blueish white light"...

Sig239

WTF, Did I miss something. I don't think nasty gurl said anything about LEDs. It seems to me that she(?) is essentialy wanting to make a fog/daytime driving light combo out of normal 55 watt (halogen?) fog lights.

Also I don't think she said anything about "bluish white light".

Ocelaris

Whoops, my apologies, I was doing almost the exact same thing with LEDs (dual brightness), and at the bottom of my thread there was a link of "related threads" and I followed that link... I also had in the back of my mind this thread of a similar nature which I've been active on... too many of the same sort of thing and I got them confused:

"Making some new LED fog lights for my BMW..."
http://www.hidplanet.com/forums/viewtopic.php?t=25825

It was late, and my threads got crossed...







My mistake. But on the off chance she's interested in making some nice looking LED fog lights, this guy has a nice setup if you want to see what he's done, follow that link.

Ocelaris

If she just wants the Daytime Running Lights effect, you can just get a 5 ohm, 20watt Resistor and have a relay mechanism running with that, and that will (if my calculations are correct) drop it to 75% of the power which is standard DRL...

http://www.digikey.com/scripts/DkSea...470587&Site=US

5$ a pop + 15$ for relay, fuse, + wire, 25$ for both...

Sig239

Those do look pretty freaking sweet! Of course looking sweet and being legal don't always go together. There are very tight specifications regarding the lighting on your car, especially headlights, and brake/tail lights. You should consider this before driving on the public roads with your light mods.

LEDs may put out less light overall, but it is in a much tighter pattern. The last thing you want is to either blind someone behind you with your homemade super duper bright LED brakelights, or alternately cause them to crash into you because they are at *just* the wrong angle to see them narrow beams; particularly if you are on a motorcycle- think about it! I don't mean to rant, I just don't want to be the one to crash........

Ocelaris

How about this? Simple Automotive Relay, Toggle switch in the cabin, and 20w 5ohm tubular resistor... it's gonna get hot, but that's the easiest cheapest way to run it... somebody would have to redo my math, might need 2 of those, one for each headlight to bring 14.5v (running car voltage) down to ~10volts which I calculated as ~1 amp dropping 4.5v is that 5watts? Or is it 1amp * 14.5v = 15watts?

I used to know where to find a 20$ DRL module, but now they're all 35$ and up, so thought I'd share this... because that's all the DRL modules are.

Ocelaris

Those aren't my lights by the way... on my car, I don't do anything special, don't need to, have a cage to protect me.

On my bike, and I don't want to steal this girl's thread, but from personal experience, it's ALWAYS someone who doesn't see you who is the problem. It's never happened that people drive head on into too much light.

I run with my high beams on at ALL times (except when behind someone in traffic), I always let up on my brakes when there's someone stopped behind me, exacting every courtesy, but when it comes to driving in the dark, it's life or death, and I'm going to throw every allowable lumen (and then a bit more) of red/orange/white wherever permissible out for my own protection.

I've done my lumens calculations, and I'm within 10% of the OEM specified lumens anyways... It's just that MY lumens are monochromatic, and halogen are filtered, so mine appear brighter... but that's ok, that's what I'm trying to do.

NastyGurl, If you want a better non-schematic drawing of how to do that, let me know I can throw one together with the relay picture... something like this: