Design you own LED lighting... - Wrist Twisters
Thread Tools Display Modes
post #1 of 5 Old 01-27-2006, 07:18 AM Thread Starter
Legatus Legionis
SV650s's Avatar
Join Date: Jan 2006
Location: The woods of CT
Posts: 9,680
Rep Power: 1

Awards Showcase
Community Leadership Donation Donation Community Leadership 
Total Awards: 6

Design you own LED lighting...

Thought this might be of some interest, why not design and make your own display for blinkers, tail lights, or running lights. You could convert your stock or aftermarket lights to LED's. If you're handy with a soldering iron and can follow a wiring diagram you can do it. The hard part is figuring out the proper dropping resistors. Thanks to the handy LED series/parallel array wizard it takes the guess work out of play.

has a wide variety of 3mm or 5mm LED's in various colors. You would need a small blank circuit board (usually green in color) and a thin strip of aluminum to mount the LED's. The circuit board can be purchased at Radio Shack or you can be creative.

The cost is minimal and the worst thing would be a blown fuse if you screw up.

SV650s is offline  
Sponsored Links
post #2 of 5 Old 06-03-2010, 11:09 PM
Machine Head
ideajones's Avatar
Join Date: Jun 2007
Location: San Jose
Posts: 1,168
Rep Power: 1

Awards Showcase
Total Awards: 1

LED license plate light install

I'll be riding at night more often so finally got around to cutting a hole in the taillight lens for a plate light.

There's gold in them hills
ideajones is offline  
post #3 of 5 Old 06-04-2010, 09:51 AM
(Quintus) Pilus Prior
The Shadow's Avatar
Join Date: Jan 2009
Location: Boulder, Colorado
Posts: 2,762
Rep Power: 1

Awards Showcase
Veteran Extraordinary Ride Wrist Twisters Event Attendance 
Total Awards: 3

Nicely done!

Well, fire the engines! Spur this iron space-pony on!

"The Shadow"
The Shadow is offline  
post #4 of 5 Old 06-04-2010, 02:46 PM
Let's go!
rmb's Avatar
Join Date: Aug 2009
Location: Sussex Couty NJ
Posts: 7,657
Rep Power: 1

Awards Showcase
Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance Wrist Twisters Event Attendance 
Total Awards: 9

Nice job, looks good.

rmb is offline  
post #5 of 5 Old 06-04-2010, 03:00 PM
Old, Bold rider
robtharalson's Avatar
Join Date: Jan 2007
Location: Aurora, Colorado
Posts: 2,463
Rep Power: 1

Awards Showcase
Donation Veteran Community Leadership 
Total Awards: 3

First, some basics:

Current is expressed in Amps, so for small values such as 20 milliamps (mA), divide by 1000, or just slide the decimal place 4 places to the left, meaning 20mA = .02 amps.

In a series circuit the voltage varies depending on where you are measuring it, but the current is the same anywhere it's measured in the circuit. An example: six LEDs connected in series would need 12V to light, but only draws 20mA, the same amount as any one of the LEDs.

In a parallel circuit the voltage is the same wherever it's measured, but the current varies depending on where it's measured. An example: six LEDs connected in parallel would need only 2V to light, but would need 120mA (6 * .02) to light. Both of these principles will be important when making a series / parallel array.

When designing an LED array be sure to use a system voltage of 13.8 volts -- it's an industry standard value for an automotive electrical system while the engine is running, also valid for motorcycles. If you want to check your voltage do so with the engine turning at least 3,000 RPM and design accordingly.

And Ohm's law:

Voltage = Current times Resistance.

Current = Voltage divided by Resistance.

Resistance = Voltage divided by Current.

Wattage = Voltage times Current, or Resistance times Current squared, or Voltage squared divided by Resistance. This is useful to determine the wattage of a resistor. Always round up to the higher wattage value.


The Wizard is a nice find, but it does have it's limitations as far as resistor values are concerned: it rounds up to the nearest common value of 10% resistor, usually resulting in less brightness than the LED is capable of.
An example from the calculator: one LED (2volt at 20mA) driven by a system voltage of 13.8 volts returns a resistor value of 680 ohms. This arrangement will give an LED current of 17.6mA, and as LED brightness drops off significantly with a decrease in current the brightness may not be what you had in mind.

To calculate the actual resistance needed first you need to subtract the LED voltage (2V) from the system voltage (13.8) and divide that by the LED current in amps. 11.8 / .02 = 590 ohms. If you are connecting two or more LEDs in series multiply the individual forward voltages by the number of LEDs, subtract that number from the system voltage, then proceed with the resistance calculation. You will undoubtedly come up with a resistance value that isn't available but can be made with two resistors in series (just add the values together), or parallel (a bit more complicated: it's 1 / (1 / one resistor + 1 / the other resistor). In this case you could connect a 200 ohm and 390 ohm resistor in series to hit it right on the head. Whenever possible use 5% tolerance resistors, there are more values to choose from than 10% tolerance.

Things get a bit more complicated when you want a dual brightness light such as a brake / taillight or driving / turn signal light. In these cases you must design two separate circuits and distribute the lower brightness array LEDs amongst the higher brightness array LEDs to insure even distribution of light in both modes. This can make the circuit board design a real bear, and requires some experimentation to get the LEDs in the right position for even light.

One last thing: However you decide to interconnect the LEDs, make sure all the connections are secure enough to survive vibration and shock loads common when riding -- a single failed connection could stop one series array from lighting, or blank out the whole light. Obviously, you will have to have the proper soldering iron (30 watt or thereabouts is about right), use only rosin core electronic grade solder, and know exactly what you are doing when soldering not only to make a secure connection, but also to prevent overheating the solid state LEDs which will either kill them immediately or significantly shorten their life.



If it has already been done, it is safe to assume it is possible to do it.
On the other hand, if it has not been done never assume it is impossible to do it.
------- Rob --------
robtharalson is offline  

Quick Reply

Register Now

In order to be able to post messages on the Wrist Twisters forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

For the best viewing experience please update your browser to Google Chrome