Topic: Resistor needed for LED Turnsignal/Taillight??

[Cabilao]

I start ordering parts for the rebuild of my bike. The seller of the LED turnlights and taillight advice me to buy also resistors for each of the lights. Is this needed?? One is 10$,times 5 is 50$. Have no big knowledge with LED`s, any advice???

[jamesb]

I just bought a electronic flasher for my LEDs and it works fine a two prong with ground lead. auto parts store less than $10.00 average

[2wheels]

each LED needs a resistor when run from 12 volts.  I use 4700 ohms.  Some units like your turn signals have more than one LED inside, that changes what resistor is required.

Check ebay, but resistor are cheap.  Any resistor will do, they are rated in watts and you can use 1/4 or 1/2 watt.  Anything bigger is a waist.

You should also show us a diagram of how you want to hook things up.  Before you buy parts.
It is a little more complicated them putting a 12 volt light bulb on.

[Bailgang]

each LED needs a resistor when run from 12 volts.  I use 4700 ohms.  Some units like your turn signals have more than one LED inside, that changes what resistor is required.

Check ebay, but resistor are cheap.  Any resistor will do, they are rated in watts and you can use 1/4 or 1/2 watt.  Anything bigger is a waist.

You should also show us a diagram of how you want to hook things up.  Before you buy parts.
It is a little more complicated them putting a 12 volt light bulb on.

I'm not trying to dis you 2wheels, I'd just like an explanation. Before installing LED's on my 550 I researched the topic first and the resistor issue came up and I still haven't figured out why a resistor is needed. As it stands now I have LED front turn signals and an LED tailight, other than installing an electronic turn signal flasher the wiring is untouched and everything works like a charm, it was literally plug and play. I could understand it if I was using the old thermal flasher but that's why I chose the electronic flasher from the start. Electronics has never been my expertise so what is it that I'm missing in regards to having to use a resistor on each LED?

[2wheels]

Hey Bailgang
The last request I made of the OP was to show us what he's got.  So folks like you could chime in and tell us what is and what is not required.  As you say you didn't need any resistors with the units you have. 
So no dis taken.

However the OP was told he needed resistors so I was going with that.

I guess there are 2 very different reasons to need resistors.

One - if the LED lights are designed to work with 12 volts, then you need a resistor to draw enough current to make the old style flasher unit operate.

Two - if the LED lights are just the LED by itself, then connecting it to 12 volts would destroy the LED.

[Bodi]

1: The actual LED chips need series current limiting resistors of the correct value for the LED type and the voltage to be applied. These do not dissipate much power and usually a 1/4 watt resistor is used. There is no way one of these costs more than one cent in quantity, possibly at Radio Shack you'd pay $2.00 for a couple of them (and be getting raped).
LED signal lamps draw very little current (less than 1/10 amp) and this is not enough to activate electromechanical flashers. The best fix is to buy and install an electronic 3 terminal flasher. The crudest fix is to add load resistors that draw as much power as the old filament bulb. That's probably what this guy wants $10.00 for, still about $8.00 more than what you could make it for yourself.

[Cabilao]

thanks for the comments,guys. i read also other posts about this topic and found lot of different advice. luckily i dig up a pair of handlebar end blinckers on ebay and go with them. only taillight will be led. had this handlebar flashers already before on my z900 and was happy. and no hassle with resistors. but thanks again.

[Bailgang]

Hey Bailgang
The last request I made of the OP was to show us what he's got.  So folks like you could chime in and tell us what is and what is not required.  As you say you didn't need any resistors with the units you have. 
So no dis taken.

However the OP was told he needed resistors so I was going with that.

I guess there are 2 very different reasons to need resistors.

One - if the LED lights are designed to work with 12 volts, then you need a resistor to draw enough current to make the old style flasher unit operate.

Two - if the LED lights are just the LED by itself, then connecting it to 12 volts would destroy the LED.

I hope you didn't take my question the wrong way and or taking this topic off track but it was a question that was of genuine concern to me and I thank you and Bodi for filling me in. With my limited electronics knowledge, even though it seems like all is working well for all I knew it might be because I've been lucky. I got mine from super bright leds, it's been a while since I've been back to their site but I vaguely remember them recommending resistors even with their electronic flasher (I got mine from local auto parts store) and that's when it didn't make sense. I'll have to check their site out again to see what applications they were referring to because the LED's I chose were direct replacements for the 1157 bulbs.

[jamesb]

If you have just front LEDs and the rear regular filament they will work fine. But if you go with the rear LEDs you will need the electronic flasher which you already have. My 74 cb550 has led brake/tail and tag lights. And front/rear turn signals. I just used a 2 prong electronic flasher with a ground lead. all of its been on the bike for a year now and I haven't had a problem yet. I'm not running any resistors at all. I've done auto electric for several years for a company and people over think the automotive electronics to much which is why my table always has bread and butter on it.