Resistor help

alan · Post by **alan** » Wed Dec 20, 2006 5:15 pm

Finally fitting (trying) to fit my resistors for my l.e.d indicators how many resistors per indicator.

A how to would be great as my electrical knowledge goes as far as a light bulb and plug change.

cheers from a bright spark not

Post by **sirch345** » Wed Dec 20, 2006 5:33 pm

From what I've heard the resistor idea is not that successful!
I just purchased a flasher unit from Motrax and that works a treat, no messing about with each indicator

That's as long as you have leds front and back

This is what you need, I got mine locally for Â£20 iirc

http://www.performancemotorcycleparts.c ... ash_it.htm

alan · Post by **alan** » Wed Dec 20, 2006 5:38 pm

Hi Chris how much was the flasher unit

Squiffythewombat · Post by **Squiffythewombat** » Wed Dec 20, 2006 7:27 pm

alan, im surprised you didnt check ebay?

http://cgi.ebay.co.uk/LED-INDICATOR-RES ... dZViewItem

alan · Post by **alan** » Wed Dec 20, 2006 7:35 pm

Hi Toby i have the resistors, Chris is on about a flasher unit its different.

But looking at the link i presume you only need one resistor for the rear and one for the front.

I bought 4 presuming i need one for each indicator can someone explain if i need one for each.

Post by **sirch345** » Thu Dec 21, 2006 10:16 am

alan wrote:Hi Chris how much was the flasher unit

The price is in my first reply, I may have added it, along with a link just as you were posting a reply

I don't know which resistors you have, but iirc the Motrax ones each had a little heat sink attached to them to basically waste the not required extra current (as the leds are a lot less wattage than the standard bulbs) they have to be fitted (earthed) to the frame of your bike

As far as I know you will need one resistor per indicator on all Jap bikes. I would imagine with the Harley the reason you only need two (if that is the case, as in the Ebay ad) instead of four is because the resistor is fitted at the power source once it's left the flasher unit (therefore each resistor will have twice the resistance as the individual ones) IE one for the left side and one for the right.

I knew I had heard something against indivdual resistors, (my memory is better than I thought) and I have found the link below, it does appear that some members have had success from using them, anyway have a read and make your own mind up

http://www.vtr1000.org/phpBB2/viewtopic ... indicators

Max · Post by **Max** » Thu Dec 21, 2006 12:49 pm

I have 2 resistors one for left and one for right(LED's front and back). they are from RS and are mounted to the frame under the back seat. the heat sink is quite large. I have been using them for quite a while now and have had no problems. I actually bought the modified relay thingy last may but haven't fitted it yet.( got from busters)

alan · Post by **alan** » Thu Dec 21, 2006 1:58 pm

Cheers guys the resistors i have mount to the frame by the look of them,there is no heat sink on them though just grills abit like regulator/rectifier i will post a pic they only cost 2.50 for 2 so dont know how good they are if price is a reflection.

Squiffythewombat · Post by **Squiffythewombat** » Thu Dec 28, 2006 4:32 pm

alan wrote:Cheers guys the resistors i have mount to the frame by the look of them,there is no heat sink on them though just grills abit like regulator/rectifier i will post a pic they only cost 2.50 for 2 so dont know how good they are if price is a reflection.

Could always solder a heatsink on? or a 10mm fan if you want to be ultra cool! ive seen people mount 80mm deltas on rectumfriers before!

Stormin Ben · Post by **Stormin Ben** » Thu Dec 28, 2006 7:40 pm

According to my GSE physics

W=VI
W = wattage = 21W
V = voltage = 12v

:. Current drawn is 1.75Amps

Now V=IR
so R=V/I
=12/1.75 = 6.85 Ohms per indicator TOTAL
NB you will need to measure the reistance of the LED indicator

Alternatively you could shell out on these
http://www.toolparts.co.uk/acatalog/LED_Indicators.html

Wildfire · Post by **Wildfire** » Fri Dec 29, 2006 8:50 am

On a similar vein......I'm wanting to switch to LED's on the back light, but wanting to keep the Red lens as opposed to the clear LED/Lens kit you can buy....
I've seen some bayonet type clear LED's that should be a straight swap for the existing bulbs...or am I missing something

delmeekc · Post by **delmeekc** » Sat Dec 30, 2006 4:13 pm

My 1p's worth.

Are you using the resistors in series to drop the voltage so that you do not pop the led's on over voltage? if so then you need the max current draw of the led's (probably between 20 and 30 mA) and the design voltage and max voltage (probably 3v and 5v respectively). Get these figures then do some maths using the charge voltage and not 12volts, so about 14.4v.

If you want to use the resistors in parallel to make them flash at the correct rate then you need (have to check) to replicate the normal load on each side (left and right) based on the resistance of the original bulbs and then the resistor will also have a wattage/power rating too and probably be a large ish, AAA battery size one as it will also be dissapating heat.

RS is the place or ebay.

Max · Post by **Max** » Sun Dec 31, 2006 9:23 pm

Got mine from RS, either 25W or 50W can't remember, couple of quid for a pair. they have been working fine for about 18 mths and at least 2 MOT's.
the motrax LED's didnt need the current limiting resister just the paralell one to restore the correct flash rate.
Just checked my old post they are 3.9 ohm 50W resistors fitted july 2004 still working.

http://www.vtr1000.org/phpBB2/viewtopic ... ght=#13684

alan · Post by **alan** » Sun Jan 07, 2007 3:11 pm

The resistors i have but not fitted are 20 ohms and 25 watts paid a fiver for 4, still hav'nt a clue how to wire them up so i will probably go for the flasher relay unit as Sirch mentioned.