| Author | Message | ||
     Doerman |
I know you can get a different flasher relay to alleviate the "fast blinking" syndrome when switching out the bulb turn signals to LED. However, it should be possible to put an in-line resistor to simulate the resistance in the bulb, right? So I looked it up in the manual and the 10W turnsignal bulb draws .74AMP. Using Ohm's law and assuming the LEDs have near to none resistance, that means I need a 16 OHM resistor. I get one from Radio Shack and put it in line. No difference, still a fast flash. Can somebody tell me where I am going wrong?  Here's some more background. This is for my 1125R which came form the factory with LED turnsignals. The reason I am swapping them is because I like smaller ones so I bought a LP mini-set. I was surprised to see that since i swapped LED for LED that it would cause a fast flash until I looked closer at the stock turn signals and noticed they have built in resistors. That is where I came up with the built in resistor idea. I can't figure out what the resistor markings translates to in ohms, so therefore the question. Thanks in advance. | ||
| Metalstorm |
I'd just get the LED flasher relay from American Sport Bike and swap it with the stock one. Then any LED signal will work and you don't have to deal with in-line resistors at all. Hakuna Matata  | ||
| Packrat |
I bought a kit from an Advance auto when I changed to led t/sigs.....$12.00 and I had to remove flyscreen and crimp connectors, etc,etc,etc, Wished to hell I'd known about the led relay,,,solves all the problems for a measley $20.00..live and learn..... | ||
| Doerman |
I know. The replacement relay is the way to go. I was just curious if the resistor approach would work. It should, right? The bulb takes .74A and with a 12V system and according to Ohm's law that should mean a 16 OHM resistor simulates the bulb load, but it did not. I was just curious about where I messed up my calculations. | ||
| Sparky |
Dman, your calculations are correct, but you said you put the resistor in line. Try putting the resistor in parallel with the LED. That way, 0.74 A current will flow trough the resistor allowing the blinker to operate while providing +12 VDC for the LED. | ||
| Midknyte |
Ok, I need a refresher on things electrical... Why, in a parallel circuit, is the resistance of the whole circuit not simply that of the least resistant branch? Or even less? | ||
| Sparky |
Mk, you are right, but the total resistance will be slightly less than the least resistance. For two components in paralled, the whole circuit resistance equals the product divided by the sum. So if the two resistances are, say 16 and 1000 ohms, the parallel resistance is 16000 divided by 1016 which equals 15.75 approx ohms. The majority of current flows through the resistor; the LED draws negligible current. | ||
| Midknyte |
Is the resistance of an LED signal greater than that of a bulb then? I was thinking that since the LED signals draw less power, their resistance was lower and the goal was to increase the resistance across the circuit to make the relay flash correctly. I've had it backwards then? | ||
| Sparky |
Geez, I'm the one who had it backwards. Sorry, I was mistakenly thinking that LEDs operated as voltage devices. No, they need to be current limited. I should've done basic research before putting mouth in gear. Dman, forget what I said about putting a resistor in parallel with a LED. Use this LED calculator tool to correctly calculate the needed resistor to be put in series with the LED. There's more useful info regarding why do I need a resistor with an LED buried in that site. Today's a good day; I actually learned something. | ||
| Packrat |
Radio Shack has resistors for like $0.95 each--my buddy tells me AFTER I spend $12.00 on a resistor "kit" from auto supply store..dammitman !! | ||
| Midknyte |
at least you didn't pay $40 for one on ebay | ||
| Reuel |
Less power is higher resistance. 12 volts, 12 ohms=1 watt. 12 volts, 120 ohms=0.1 watt. | ||
| 75aztec |
I just bought the turn signal flasher from American sportbike and plugged it in. I'm resistor resistant. Especially after seeing the way the previous owner had several taped together for the tail light! I replaced his tail light with another LED unit and have had no problems. I have had friends driving behind me comment on the brightness of the brake light and turn signals. Be SEEN! | ||
| Smiley1eye |
"I'm resistor resistant." Too-funny!  I started out with the LED load equalizers (aka resistors) because I had 3 wires to deal with and didn't feel smart enough to figure it out. Well after messing with the damn things for almost a year, I finally decided to figure out if they would work without or what I would have to do to make them work. Turned out to be a non-issue. Just hooked it up using both wires (fast flash) then one wire (no flash) then the other wire (fast flash again) then stuck in the new flasher relay from American Sport Bike and I was good to go without that big mess with the resistors! Shouldn't have waited a year to do it. | ||
| Usmoto |
If you go to this web page: http://led.linear1.org/led.wiz it will tell you which resistor to put in the circuit depending on the how many and which led's you use. If you click on the "wiring diagram" button, it will show you a pic of how to wire the whole circuit. I'm presently re-building my 1125r rear turn signals because they stopped working. There is also a lot of info on leds on this site: www.theledlight.com. I learned a bunch about leds from there. (Message edited by usmoto on March 16, 2009) (Message edited by usmoto on March 16, 2009) |
