Hi. I'm completely new to the forum and new to LED's and electronics at all save the last week and a half when i decided that i wanted to install some led brake lights/turn signals into the saddlebags of my motorcycle. I looked at automotive stores and online but found nothing that seemed like it would work so i did research on how to make an led array. The internet is a great resource and i've got it all done now but i ran into a problem, not all of the blinkers in my array come on. So you know, its a 2x5 inch board, 96 leds per board. The blinker side of them is 32 yellow leds, arranges in series of 6 then connected in parallel with an 82 ohm resistor (one series is 3 leds with a 220 ohm resistor). When i wire them in with my existing blinkers, only 5 leds total come on, and not in the same series. I know that they all work, because when i connect them to the brake lines, all are on and bright. Any idea why they arent working with the blinker lines and how to fix it?
Turn signal upgrade
- Thread starter terizius
- Start date
Help Support Candle Power Flashlight Forum
Gryloc
Enlightened
I am in a late night (early morning) haze, so I hope I got the jist of your problem. Does those LED attached to the blinker side of the circuit flash, or just stay on continuously? I ask because yout old fashioned blinker (the thing that goes tink-tonk lol) need a load to heat up the little bimetallic strip inside. Therefore, it may not blink, or it may not come on (not totally sure). You can fix that by attaching one of those light bulb simulating load resistors in series with the LEDs, or you can get an electronic flasher (no load necessary being digital).
Other than the flasher, just make sure that all connections are secure, and all LEDs are in the correct polarity. Is it possible that the polarity of the flashers are backwards? I have an '89 dodge dakota that had the center pin being negative and the outer shell be positive on the rear flashers
. I do not know if that was the previous owner's doings, or if it was something required for the hazard and turn signals to work correctly (stupid sounding, but the things only worked perfectly in this configuration). To get my homemade 3rd brake light to work, I had to play with relays and diodes to get it to work. Later I decided to use the wire directly from the brake switch for reliability reasons.
Just to be safe, check everything with a voltmeter to make sure that the socket is getting a voltage or not (and check the polarity). Play with hooking a wire to the two different flash and brake circuits of your LED fixture to your battery directly to make sure everything is solid. I can't think of much more now. I will check back later...
-Tony
Other than the flasher, just make sure that all connections are secure, and all LEDs are in the correct polarity. Is it possible that the polarity of the flashers are backwards? I have an '89 dodge dakota that had the center pin being negative and the outer shell be positive on the rear flashers
. I do not know if that was the previous owner's doings, or if it was something required for the hazard and turn signals to work correctly (stupid sounding, but the things only worked perfectly in this configuration). To get my homemade 3rd brake light to work, I had to play with relays and diodes to get it to work. Later I decided to use the wire directly from the brake switch for reliability reasons.Just to be safe, check everything with a voltmeter to make sure that the socket is getting a voltage or not (and check the polarity). Play with hooking a wire to the two different flash and brake circuits of your LED fixture to your battery directly to make sure everything is solid. I can't think of much more now. I will check back later...
-Tony
tony, thanks for replying to my post. I, like you, was in that post pm haze apparently because i realized this morning that i had used the incorrect value resistors across the board on that side. I've replaces them and am going to test it out first. in case you're doing more pondering though, i've tested that side with the brake lines and all lights worked perfectly then. when i hook it to the turn signals is when i have the prob. I've simply spliced the wires into the existing turn signals for now, so that i dont have to worry about the load resistance issue. I've also rechecked all connections and they seem secure, supported by the fact that they work with the brake lights. I tested the voltage going to my running lights, 12.1v. couldnt really get a steady reading on the blinkers due the them going on and off.. meter just kept jumping around, but highest i saw was about 9v. could that be the issue?
Well, i just tested the board with the new resistors in. First test with the brake light lines, perfect. Again, when i go to the turn signal lines, only get 6 total to come on. half of one series, and all of my last series of 3. the rest dont do anything. Any other suggestions? i'd prefer to just be able to stay tied into the existing lines.. but i may have to go with the electric flasher.. bleh. i should have just bought some aftermarket 
TorchBoy
Flashlight Enthusiast
Still double posted.
Torchboy, i dont know how to remove a post, but if you'll give me instructions, i'll happily remove the one i have in automotive. Regarding your question, i have 32 total yellow leds, 4 series of 6, 1 of 5 and 1 of 3. each series is then wired together in parallel. i decreased the resistance value so i currently have a 39 ohm resistor in each series of 6, a 120 ohm resistor on the series of 5 and a 270 ohm resistor on the series of 3. I tested them again with my brake light and realized that the series of 5 and 3 are brighter than the others of 6. Also, it is the series of 5 and 3 that come on when i connect them to the blinkers. My power supply is the pos and neg leads to my rear blinkers on my motorcycle. i know the voltage the the brake light is 12.2v, i assumed the same would be true for the blinkers. Anything else? I really appreciate the assistance.
TorchBoy
Flashlight Enthusiast
Send a PM to the mod for this forum, and ask politely to merge the threads (or delete one). For who the mod is look at the bottom of the automotive forum page - there's only one mod here last time I looked.
My first guess is simply that there isn't enough voltage coming from the indicator wire. How many volts do the LEDs each require for the current you want to run them at?
Are you serious about only three out of a series of six working? Do they all have the same operating voltage?
My first guess is simply that there isn't enough voltage coming from the indicator wire. How many volts do the LEDs each require for the current you want to run them at?
Are you serious about only three out of a series of six working? Do they all have the same operating voltage?
no, its not 3 out of a series, its a series of 3(compared to the other series that are 6 and 5 led's) i'd post a drawing if i could.. but again, i'm new to forums and not sure how. anyway, it set up thus..
series of 6, series of 6, series of 5, series of 6, series of 6, series of 3.
positive connects to the first of each series, neg to the last. all series are wired together in parallel. The series of 3 is the brightest (seems to be the correct brightness compared with the red leds i'm using for brake/running lights), series of 5 is dim, all of the series' of 6 are barely on... still thinking it's a power issue, but i replaced the resistors in the series of 6 from 39 ohm resistors with 1 ohm's, and still no real improvement...
series of 6, series of 6, series of 5, series of 6, series of 6, series of 3.
positive connects to the first of each series, neg to the last. all series are wired together in parallel. The series of 3 is the brightest (seems to be the correct brightness compared with the red leds i'm using for brake/running lights), series of 5 is dim, all of the series' of 6 are barely on... still thinking it's a power issue, but i replaced the resistors in the series of 6 from 39 ohm resistors with 1 ohm's, and still no real improvement...
Last edited:
TorchBoy
Flashlight Enthusiast
You did state that only three out of a series of six were on, now you appear to be saying it's not like that, but it still sounds like there's not enough voltage for them.
Do you know what the operating voltage of those LEDs is, and have you tried using http://ledcalc.com/ ?
my mistake, that was before i switched out the resistors. I ordered the LED's from ebay, it it stated there that the operating voltage was 1.8-2.1v. And i've been using the led calculator from www.led.linear1.org/led.wiz. i had been using the suggested 13.4 voltage for automotive/vehicle use. i'm beginning to think that may not be accurate with the motorcycle, again, voltage from the brake light was about 12.2v. if thats the case, and using the max led voltage of 2.1, i would only be able to put 5 led's in series, not 6 as i currently have. I have another board that i was working on before, that i may see if i can't do some experiments with. btw, i pm'd the mod and requested the other post to be removed.
hey, i was doing some more thinking about this problem. with the bike off, i'm getting 12v from the brake lines. 13.5v with it on. again, i cant really test the blinkers because they flash and i cant get a steady reading.. but the max voltage i saw was about 10.5v. significantly lower than the brake lights. Anyone know if the blinker relay might be limiting the voltage??
TorchBoy
Flashlight Enthusiast
That's a pretty neat calculator, and it's nice to have three different output options. Unfortunately it's wrong.
I tried entering 10.5 volts for the supply, and a total of 32 LEDs, each operating at 2.1V and 20mA. The wizard's solution is to put them in strings of 5 LEDs, each string with a 1 ohm resistor. 5 x 2.1V = 10.5V, which means there wouldn't be any voltage dropped across the resistor, so the LEDs would actually have to be operating at less than the specified 2.1V.
Enter the operating voltage as 2.101V and it gives a much better layout.
Even if it was right, having that small a drop wouldn't be very safe or stable, and so probably not a good idea. In an automotive setting voltages can vary considerably. For example, my LED car interior light gets anything from a little over 12V to almost 14V.
For automotive, in general, for safety, the LEDS still need to come on at 9V. Not bright, but on. Those LEDS may have a forward voltage more like 2.5V at the rated current I would expect. Generally for the design, you would use 16V and 20mA(approximately) to set the resistor so you do not kill them if you have a high regulator. That said, you could probably get by with 14.5 or so and 20mA. It is highly unlikely when the engine is revved you are putting much over 14.5 to the LEDS.
I would suggest no more than 4 LEDs in series (most automotive designs would be 3). This will ensure enough voltage drop across your resistor so they always light no matter what the battery voltage. You are better off with 3 and more resistors for the most reliable operation.
That said, when someone runs into your rear-end, don't expect any insurance compensation for your injuries and even expect to be sued as you are running non-tested, non-compliant lights. You would be far better buying an off the shelf tested unit that is known to comply.
Semiman
I would suggest no more than 4 LEDs in series (most automotive designs would be 3). This will ensure enough voltage drop across your resistor so they always light no matter what the battery voltage. You are better off with 3 and more resistors for the most reliable operation.
That said, when someone runs into your rear-end, don't expect any insurance compensation for your injuries and even expect to be sued as you are running non-tested, non-compliant lights. You would be far better buying an off the shelf tested unit that is known to comply.
Semiman
TorchBoy
Flashlight Enthusiast
That would be with white LEDs with a Vf of ~3.5V. Red (edit - and yellow) LEDs have a lower Vf, so 4 in series should be fine, even with a 9V supply. But like you say, it would be good to know just what the Vf of these particular LEDs is.
Last edited:
I have been thinking out the situation and am currently in the process of mocking out a new board on autocad using series' of 4 for the yellow blinker led's as well as the red brake light leds. I too wish that i knew the exact forward voltage, but again, only the range 1.8-2.1 is listed for both. I dug around in my motorcycle manual and found that the blinkers should be on the same 12v system as the rest of the bike, so no voltage drop there. I would assume then that the yellow led's simply have a higher operating voltage than what i was inputting. Regarding legal aspects, i'm not replacing any stock lights at all. These lights are going into a set of removable saddlebags (plastic type) and will only be providing more lighting, not removing any existing lighting. That being the case, i dont expect any potential for legal issues. Additionally, the whole reason i'm making them myself is that there is no producer of lights for this application, at least not for these particular bags. I have high hopes for this redesigned board, i learned a few things i need to do different from the last ones.. Again, thank you for the replies
TorchBoy
Flashlight Enthusiast
I think that's one of the best part of doing projects like this - the maker learns so much. And if we can help without confusing things too much, so much the better. :thumbsup:
I said "AUTOMOTIVE" designs TorchBoy, not hobbyist designs. Automotive design MUST work at 9V (8V with some car makers). They do not have to put out much light, but they need to light. This is for safety reasons when you are sitting dead on the side of the highway. Hence, even with very low voltage LED, i.e 2.5V, they often only use 3 in series. The other issue is that they must work up to 16V continuously (actually higher, but usually it is clamped). Hence, they also use less LEDS and allow more drop in the resistors to ensure they have reasonable currents no matter what the voltage.
Semiman
Semiman
TorchBoy
Flashlight Enthusiast
That's OK, SemiMan. The more volts dropped across the resistor the more stable it'll be. I was just pointing out that just three red or yellow LEDs don't have to be used - even for automotive designs - as though it's some magical number. The Vf of white LEDs doesn't allow that option though.
