Creating a dual circuit element for lights

Preface
This is a description for making a dual circuit element which will make LED arrays, lights, etc function as both running and brake lights. This circuit is to be used with LED lighting only as trying to use this same circuit on incandescent bulbs (unless extremely low wattage) will likely burn the circuit up and could potentially cause a fire. This project affects parts of the electrical system on your bike so if you should decide to undertake this task be aware this project could result in damage to your bikes electrical system if done improperly. Any similar work performed on your vehicle is done at your own risk. Legal mumbo jumbo out of the way, let's get started.

Preparation/supplies

2 diodes (part# 276-1103) - available from Radio Shack for $.79

1 150 Ohm resistor (part# 271-1109) - available from Radio Shack 5 for $.99

Scrap pieces of wire, anything 24 gauge or bigger should be sufficient

Soldering iron

Heatshrink tubing

Process
This isn't so much a process as it is just soldering the circuit together and doing a small bit of testing. This is the circuit we'll be building:

You can test the circuit ahead of time by making temporary connections between all the components and using a car battery or 12V power supply as a power source. I've experimented with different resistor values (100, 150, 200 Ohm etc) to get the appropriate "difference" between running and brake brightness and you should too since each LED array will be slightly different. If you get as high as 600 or 700 Ohms you will see as much as a 50-75% difference in brightness. I find the 150 Ohm usually works as a good starting point but with such small costs associated with the price of these 1/2 Watt resistors you should be able to afford to test out a few different sizes to get the look you desire. Once you settle on a resistor for your circuit use your components, wire, solder, heatshrink tubing, etc to assemble this circuit and insulate the parts from making contact that they shouldn't. I recommend using different color wires for each lead on the circuit so you can later distinguish which wire goes where, but you can just label them if you want too. Once the circuit is completed and you've got enough extra wire coming from both ends to make your connections, you can enclose the entire assembly in heatshrink tubing, electrical tape, or even liquid electrical tape so that there is less hassle of where to safely locate the unit. Your best bet in most applications is to wire it in under the right side cover but depending on your specific needs you can also wire this anywhere that you can pull running and brake light power from.

Remember that:

Green = ground
Brown = running lights
Green/Yellow = brake lights

That's it!

Afterthoughts
This is a great little trick to save a few bucks. I've used it on a few custom bikes in specific applications to make a single LED strip, pod, etc function for both running and brake lights, running and turn signals, etc. It's a very versatile setup and for the cost associated with making one you can save several bucks and have some neat little "custom" accessories on your bike.