Hey guys, I tried searching for this question and couldn’t find an answer anywhere, so I figured this may be the best place.
According to what I Understand I feel this may well work, but i wanted to get some more opinions and/or options.
Here’s the deal, I am a volunteer firefighter and a security officer in North Carolina, US. I have installed these strobe lights in my car (for running emergency calls and traffic control): Amazon.com
Now, these are actually surprisingly nice for the price, and easy to hide (each module of three LEDs fits in my palm). However, being a tinkerer as I am, I would like to boost the perceived brightness. I would assume the LEDs are probably running at about max power already, So I am thinking about gluing mylar sheeting inside the clear plastic cover, on the back and around the sides. In my theory, should increase forward throw, and only decrease all around throw by a small margin thanks to the three diffuser type pieces built into the plastic cover. Yes, it will be tedious, but I enjoy such things lol. Opinions? tips? Ideas? thanks in advance!
EDIT: 9/18/14 Changed title since I am going a little further with this deal.
So I did this to one module yesterday, and felt it made enough difference to do it to all. I am now considering, just for sport, building my own module using the same form factor. Can anyone suggest what emitters to use and where to get them from? It would need to be quite floody for best visibility from all angles, and also whether to add in the mylar with them or not? It would also be excellent if these emitters were offered in white, red, amber and maybe green. Any ideas are appreciated.
I’m thinking about XP-E emitters, as I have found them in all colors I would need and they are rather inexpensive. Any comments at all? I would really like some more experienced opinions. Thanks.
Sounds like an interesting project. Do you have a picture of the pcb board in the control module box? The driver would part of the circuit. It may be that you can increase current.
I'm guessing the each branch has 3 5mm LED's wired in series. The type that have 4 legs (I have a bunch of them in different colors, but the name of that type of emitter escapes me at the moment). Can you tell if they are wired in parallel or series?
Finally, do the lights get hot when they are on? Increasing current much may not be an option with those types of emitters and housing.
Probably the best emitter would be an xml since they are very efficient and are now outdated (maybe you can get them on the cheap). Do you need a specific color?
If you have a Metal Supermarkets store near you, think you could go check out their aluminum angle. Smallest I see online is 3/4", but I would suggest just visiting them and seeing what they have (plus, their prices are usually much better at the store level). Check their scrap barrel while there (that stuff is sold by weight). An "L" shape could be used to provide a back for the emitter bases and also for a bottom for the lights. You could attach magnets to the base part. The aluminum would help with getting rid of the heat.
I will attempt to post up some pics this evening, as I am currently at work. I feel that the driving is handled by the control box, as the circuit boards on each individual module only have the 3 emitters, a resistor, and the hot and ground wires. the circuit board inside the control box is very simple as well.
The emitters are of the square type that are used in the flashlights we all love lol. 5mm looks about right, though I have not measured them. they are mounted directly to the circuit board, which has rubber/foam spacers between it and the simple metal angle bracket the assembly is mounted to. I have ran them for about 5.5 hours straight with no noticeable heat coming from them.
I will be adding mylar to the set of red that I have in the back window of my car tonight so i will be able to get some more detailed information and pictures of the whole deal.
As far as colors I need at least white, red and yellow/amber. Green may be used as well though I have yet to decide
Hmmm, the resister in the lights sounds like the controller is just turning on and off voltage from the vehicle. The resister would be used with a string of 3 absorb the excess voltage that the 3 LED's in series could not use. I'm guessing your emitters will look like this:
The resistor will have color bands that are a code to say how many ohms of resistance they are. That could be helpful if you can take a picture of the bands or tell us what colors and order the bands are in.
That sounds about right. The emitters are in a similar form as the one you posted, yes.
And I will be sure to take some detailed pictures tonight. I Haven’t yet decoded the resistors and am honestly needing a little brushing up on it. I will also test the voltage going to the lights from the control box tonight as well, I’m sure that will help also. This idea just kind of came upon me and I haven’t had time to actually work towards it yet, so I apologize for not having some of the needed information. I plan to get the lights all running and installed with the reflectors and then order an extra set to test with changing the emitters, but I will get all the info and pics tonight whiel I’m tearing down the next set up for Mylar.
So here is the next unit to get the mylar treatment. These are actually red emitters, and this unit seems to be of a little better quality (which is nice since I did pay a few dollars more lol). The layout is a little different than the other set as far as locations but components look the same.
Hope you don't mind if I make you photos visible in the thread.
So the emitters are wired 3S as we suspected. Is that resister banded: Red, Yellow, Green, Black, space, Gold? If yes, I think that is 245ohm, plus/minus 5% (See chart at bottom of this post). If your vehicle voltage at idle (when lights will be on the most) is 14 volts, and the emitters use 2.2 volts each (Red emitters), then the current will be about 30mA per emitter. Here's an on-line calculator.
I'm guessing those emitters can take 70-75mA. So maybe try a 125 ohm resistor to double the current to the emitters. Monitor for overheating. You may want to order some extra emitters just in case they start frying.
I don’t mind at all, and actually thank you. I did take an attempt at the output voltage and being that it’s only for a split second I couldn’t get a solid number, however it did register as high as 10v so I feel it would be safe to assume that it is pushing full voltage through the control box.
As far as the color banding, your sequence was correct except red is actually purple, for a sequence of purple, yellow green, black, gold. That would come out to 745 ohm correct?
And yes, the white circles are just little spacers, they keep the solder joints from touching the metal bracket the assembly is mounted on.
Wow, 745 ohms. That is like just 10mA. Quite under driven if that is correct. Seems like it should be easy to increase brightness. If you have some other resisters, connect one parallel to an existing resistor (you can just hold its 2 leads against the other resistor's 2 leads) and see what it does for brightness compared to the other lights.
Hate to dredge up an old post 4wheelr, but I have obtained some yellows I wish to try my hand at. So, they are wired the same, in a yellowish/Amber color, with what appears to be a Brown, Green, Brown, Gold banded resistor. If my eyes serve me well that comes to 151 Ohms, correct? I do have a 68 ohm resistor laying around, do you suggest attempting it? I have tried to lay it across the leads of the current resistor and it seems to make a difference, but it’s hard to tell without a steady on and I’m also not sure if it would seem to be safe. Thanks in advance!
Those LED’s look like 5 mm single chip piranhas. Max continuous drive current is probably ~40 mA. It’s been a few years since I’ve played with those types of LED’s, but I remember that there used to be 4 chip models available with a ~100 mA max drive current. They weren’t reliable when used continuously, but for your project they ought to be fine.
Another option would be to pick up some genuine Philips Superflux LED’s. Max drive current is 70 mA, very reliable, and you could definitely overdrive them to 100 mA for a strobe light project. They were also available in viewing angles of 40°, 70° and lambertian. The only downside is that they have a slightly smaller footprint, however you could probably bend the pins to fit the holes in the PCB.
It’d be nice to know how much current that control box can safely source or sink per channel. If it’s a couple hundred milliamps, I’d throw some amber XP-E’s or PC amber Rebel’s in there.
I actually did consider XP-E’s, but that could get expensive (relatively speaking lol). I have placed the 68-Ohm across the original resistor, so I think I will pick up a few more of the 68 Ohms and replace the 151’s.
