Before we begin, let me state that the legality of such a device is interesting. Since the device emits an IR signal rather than a radio one the FCC has no control over its
production or possession. However the actual use of the product by non-qualified individuals would be illegal. It is probably against your STATE law for you to own & operate one of these. I must insist that you check with your local law enforcement before you even think about beginning to build one. I checked with mine and just owning such a device carries pretty stiff penalties. (not worth it)

From Michigan Law: (Why Michigan when I live in KS? Because it was easy to find, and I copied and pasted)

1. A misdemeanor and up to 90 days in jail  and a fine of $5,000 for the
   unlawful POSSESSION of a MIRT.
2. A FELONY charge with up to TWO YEARS in jail and a fine of $10,000 for
   the unlawful SALE or purchase of a MIRT.
3. A felony charge with up to FIVE years in jail and a fine of $15,000 for
   individuals using MIRT that resulted in a traffic accident
4. A felony charge with up to 15 years in jail and a fine of $25,000 for
   the use of MIRT resulting in death.

I Did a VERY Quick search on states where this was illegal, and here is what I found (This is BY NO MEANS A COMPLETE LIST. I would assume it was illegal in every state)

• Georgia
• Kansas
• Michigan
• Minnesota
• New York

`(1) SALE- A person who knowingly sells a traffic signal preemption transmitter in or affecting interstate or foreign commerce to a person who is not acting on behalf of a public agency or private corporation authorized by law to provide fire protection, law enforcement, emergency medical services, transit services, maintenance, or other services for a Federal, State, or local government entity, shall, notwithstanding section 3571(b) of title 18, United States Code, be fined not more than $10,000, imprisoned not more than 1 year, or both.

`(2) USE- A person who makes unauthorized use of a traffic signal preemption transmitter in or affecting interstate or foreign commerce shall be fined not more than $10,000, imprisoned not more than 6 months, or both.

More Legality information can be found using your states D.O.T. (Dept. of Transportation)'s website. The Official MIRT site has a great listing of these D.O.T. Site. Please read up on it. I would hate for you to go to jail over something stupid.  So why am I releasing this information?  I feel that governments (& companies) need to realize that you cant use "non-authentication" techniques to control critical systems.  Critical systems critically need encryption.

I'll also throw this in. The system uses special IR sensors to work the Pre-Emptive system, I have taken a picure of one of the sensors below. (taken at College & Lackman in Lenexa, KS)

Warning, most of the intersections that have these special sensors are the really busy ones.  Which means there's a good likelihood they have cameras too (either red light ones or the ones to just monitor the intersection). CCD cameras can pick up IR light. So if you used the light changer it would show up on camera… Just some food for though before we begin. Ok, so have I talked you out of making one yet?

Done thinking about it yet? Ok good lets get rolling, Green Lights Kick Ass... Just FYI

Parts List:

Lets start building it.

STEP ONE : GATHER & IDENTIFY THE PARTS

Luckily for us, most of the parts are available at your local Radio Shack, but you may have to visit a specialty electronics store or order from Digi-Key or Mouser to get a few remaining parts. We will be using the IR ILLUMINATOR from BGMicro for the IR Transmitter.  The PC board we will be building this on is up to you on what style you prefer. As you can see in the above picture I am using an "IC Type" but that might not be the one you want to use. A standard PC Board will work perfectly fine. The small plastic case was probably the hardest thing to find (even though you would think it would be the easiest) I ended up finding a perfect case at Office Depot. =) It had 10 million paperclips inside of it. But its up to you where you get it..

STEP TWO: THE GOOD STUFF, SCHEMATICS!

Timing Circuit

I suggest you build the timing circuit first, as it is the most complex. What this circuit is doing is creating a variable "pulse" in order to flash our IR Array. I cannot confirm this, but the word on the street is that the best results can be obtained around 10hz or 10 cycles per second. We will use the 500k Potentiometer to control the "blink rate". What I did for "bench testing" is connect a computer Molex connector to pull 12V (see Molex Pinouts) from a nearby computer. This is not required, so I didnt include it in the parts list. I then connected the anode of a red LED to Pin 3 of the IC, and the cathode to the 390 Ohm resistor (R5). Connect the other side of the resistor to ground. The LED will now flash with the IR array. At this point we are ensuring that your timing circuit is working correctly, and if it is you will have a fast blinking LED.

Now would be a good time to put your IR Array together. This is probably the most fun part of this project. Nothing like soldering 36 LEDs. All I can say about this is make sure you get the Anode and Cathode correct. (However they are marked very well) Once you have the timing circuit built and tested, the IR Array built, it is time to build a hi-power driver to power the IR Array.

Hi-Power Driver for IR Array

When building the IR Driver circuit, it is IMPERATIVE that you double check polarities on all Capacitors and Transistors. If you happen to use a metal container YOU MUST ISOLATE THE POWER TRANSISTOR (2N3055) FROM THE METAL CASE. Use nylon screws and washers, with electrical tape on the bottom of the transistor to isolate. Failure to follow these instruction will destroy your project!. Once again, check and double check EVERYTHING before you apply power!

So, who wants to design a PCB for I-hacked? =)

Now, cram it all in the Plastic box. Using the soldering Iron, melt a hole in the "Lid" of the box. Mount the IR ARRAY on the outside of the box, using some screws/nuts though the hole you just melted to hold it in place. At this time, this little project should be starting to look pretty good! It is again now a good time to test everything. Having everything hooked and powered up, you should see your RED LED Flashing at a quick pace. That tells us that the timing circuit works, but we need to ensure that the IR Array is blinking along with it. Remember how earlier I mentioned that camera's CCD can pick up IR light? Well using this knowledge you can use any digital camera or camcorder to see if it is working. Infact, you can even use your camera-phone!

STEP THREE: MAKE IT MOBILE

Cut the end off of a 12V Cigarette Lighter Adapter and connect it into your project. As in above, there is already a Molex connector connected to the timing circuit, so lets solder up a male molex to the Cigarette lighter adapter and now you have a quick connect power adapter. (Again, this is not needed, just a simple suggestion) Now you can test it out on the bench easy, or take it to the car. (not that you will be using this in an auto)

At first you may or may not have much luck, because your Hz is probably pretty off. Using the equation

R2= 100k, C1=.47uF so R1 must equal ~98k. So using a multimeter set your Potentiometer to 98k and give it a shot. If this doesnt work, try slowly increasing the blink rate.

Again, please do not use or abuse this. These Pre-Emptive systems were designed to save lives, not to get you to work earlier. Imagine if you and an ambulance were to approach the same intersection at the same time from perpendicular directions. I am not sure what the system would do, but you could possibly cause the ambulance problems getting through the light... Something to think about.

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STEP FOUR: USE IT WITHOUT HAVING ONE?

A few readers sent in some tricks of tripping the lights using the crosswalk button. However, after posting it, I received several letters telling me it was a Hoax, put on by our friends over at bbspot.com.  Well, I decided that I should probably give it a shot before blindly believing anyone. =)  I can tell you that this "Crosswalk button hack" is a hoax, sorry for misleading you!  I was tricked!