freshpl

building an MIRT **

17 posts in this topic

I haven't built this project, but their schematics look fine. The 555 is a great oscillator/timer chip -- if you've never played with one before, definitely give them a try! And, if by some insanity, you have a hard time finding them, PM me -- I have about 100 of them in antistatic tubes.

That said, don't actually /use/ that IR light-changer. A lot of old systems just change the light green, regardless of what the other light is doing. This can cause some big problems (think traffic light hack from "Hackers"), not to mention interrupt emergency service! I've heard of a similar device, called the "Chrome Box," that used a xenon strobe to change the lights, but I've also never tried it.

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That said, don't actually /use/ that IR light-changer. A lot of old systems just change the light green, regardless of what the other light is doing.

so your saying the emergency vehicles use a differ light changer? because I see the E vehicles way changes green and the other direction gets a red. or is it on old traffic lights now matter what light changer you have it will be green both ways

Edited by freshpl
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so your saying the emergency vehicles use a differ light changer? because I see the E vehicles way changes green and the other direction gets a red. or is it on old traffic lights now matter what light changer you have it will be green both ways

From what I've heard, it's just old light systems. This may or may not be true -- I've never tried it. I suppose the best way to find out would be to wait until there's no traffic on a road with properly-equipped lights, like at 3 AM, and test it out.

I've even heard it suggested that flashing high-beams with your low beam lights turned off at a fast enough rate will trigger the lights. There's not actually an IR transmitter on the emergency vehicles setting these sensors off -- the sensors just happen to be IR, but they're responding to the white strobes on most/all emergency vehices, since those strobes are wide-band as far as the light they send out.

It'd be a cool project to try on a road when there's no traffic, but using this to actually change lights just to get through quicker is plain irresonsible.

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You can check with your state to find out about traffic pre-emption devices. It's not against the law to ask. I googled about them for NJ and found a crap-load of pdf's with all kinds of information including the fact that they use 9600 baud modems for maintenance. Check your local laws. You may find out that there is nothing specific which prohibits you from owning or using one of these. In my state, NJ, it's illegal just to have one of these if you are not authorized.

The i-hacked one is called a "Dirty" mirt which means it just flashes at the signal. It will probably only work on older systems. It uses infra red so as not to be visible to law enforcement. Most (?) states now use encoded mirt's so you need to to know how to reproduce the specific signal.

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You can check with your state to find out about traffic pre-emption devices. It's not against the law to ask. I googled about them for NJ and found a crap-load of pdf's with all kinds of information including the fact that they use 9600 baud modems for maintenance. Check your local laws. You may find out that there is nothing specific which prohibits you from owning or using one of these. In my state, NJ, it's illegal just to have one of these if you are not authorized.

There's a national law in effect now, concerning MIRTs:

http://www.theorator.com/bills109/hr1122.html

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I have built this project on a bread board. Only, I used 1 infrared LED and never got around to picking up more, and of course the 1 LED wouldn't have enough power.

I didn't use those schematics, I made my own after doing some reading on the 555 timer. I then took my web cam so I could see the infrared light, I slowed it down and I got the 14 Hz like I wanted (7 flashes -- 7 on / 7 off).

Anyway, I hear that glass blocks infrared light from my old physics book, however... I have to say BS on this, since I have tested it with a camera and a window... no signs of distortion what-so-ever; I am not sure why my physics book said this... perhaps the glass I was using isn't "pure" glass or something, I don't really know.

Anyway, the schematics look good and all those LED's should be enough to trigger the preemptor. I have also heard of some stories of success of people flashing their hi-beams on/off very quickly. However, doing that 7 times in 1 second seems very difficult. However, instead of 14 Hz, I believe 10 Hz does the same thing but it is a low-priority preemption signal, so they probably have just did 5 flashes on/off instead.

Please let me know on your success if you go out and test this out, I am anxious to hear about it. Also, make sure you don't do this on a traffic light that has a camera on the top... because the camera takes a picture every time the preemptor gets triggered (at least I believe so).

Edited by ansichart
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Anyway, I hear that glass blocks infrared light from my old physics book, however... I have to say BS on this, since I have tested it with a camera and a window... no signs of distortion what-so-ever; I am not sure why my physics book said this... perhaps the glass I was using isn't "pure" glass or something, I don't really know.

You're probably thinking UV light, which /is/ blocked by glass. IR passes right through it, otherwise nightvision and greenhouses wouldn't work! UV, however, is stopped, which is why the erase windows in oldschool EPROMs had to be made of Quartz, and why you're warned never to operate a halogen bulb bare (halogen bulbs are made of quartz, so if there's no protective glass surrounding it, you can absorb some UV radiation).

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You're probably thinking UV light, which /is/ blocked by glass. IR passes right through it, otherwise nightvision and greenhouses wouldn't work! UV, however, is stopped, which is why the erase windows in oldschool EPROMs had to be made of Quartz, and why you're warned never to operate a halogen bulb bare (halogen bulbs are made of quartz, so if there's no protective glass surrounding it, you can absorb some UV radiation).

Yea, I know UV does... but my book says Infra-red. It was discussing Infra-red and Ultraviolet in the same chapter, perhaps they go t confused and it's a typo or something.

Strange though.

Edited by ansichart
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Another thing to look out for are the traffic-cams at the intersections... Some can see the iR band too and if they record you driving up with your windshield flashing some iR, I'm sure they'll get a bit suspicious. (So I want to mount mine in the headlights.... it's hot there anyways...)

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Another thing to look out for are the traffic-cams at the intersections... Some can see the iR band too and if they record you driving up with your windshield flashing some iR, I'm sure they'll get a bit suspicious. (So I want to mount mine in the headlights.... it's hot there anyways...)

Mount them inside your headlights? I don't think that will work very well, because the plastic piece that covers it will probably distort it an spread it, like it does with the visible light. So you will have the IR signal mixed in with the visible light from your headlights, and that might cause interference. Since visible light triggers the preemption. You would have to make sure the IR signal is strong enough to overpower the visible light from your headlights.

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friend of mine made this and mounted it in his grill and just wired a simple switch to the dash

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Another thing to look out for are the traffic-cams at the intersections... Some can see the iR band too and if they record you driving up with your windshield flashing some iR, I'm sure they'll get a bit suspicious. (So I want to mount mine in the headlights.... it's hot there anyways...)

Mount them inside your headlights? I don't think that will work very well, because the plastic piece that covers it will probably distort it an spread it, like it does with the visible light. So you will have the IR signal mixed in with the visible light from your headlights, and that might cause interference. Since visible light triggers the preemption. You would have to make sure the IR signal is strong enough to overpower the visible light from your headlights.

I've got two schools of thought... one) if the signal is low freq, I'll just 'pulse' the headlights for that little bit of time... Two).. kill the highbeams and mount a ir flood light array inside it... I still drive old cars... they have glass headlights. Or for that matter you could hide them in some foglights...

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Oh yea..this one works...If you need any help with the PCB/Circuit I'll try to help out...it's fairly simple....MUCH MUCH easier and less complicated than the SMT Wavebubble circuit......I put mine in my electronics box due to paranoia... I keep thinking cops are after me..sigh :| But seriously...don't get caught with shit like this.

P.S: For the PCB you can just use a radio shack board

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If you over use this, don't be surprised when they set up cameras on the stop lights or something.

I would only use this for 2 reasons:

"Dude, the movie starts in like 5 minutes, where going to be late! Fucking Red Light!" ... "Not if I can't help it!" *click*

1. To show off to your friends.

2. If you are running late.

And if they are both the case, like the above scenario... you don't have a choice, you have to use it.

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If you over use this, don't be surprised when they set up cameras on the stop lights or something.

I would only use this for 2 reasons:

"Dude, the movie starts in like 5 minutes, where going to be late! Fucking Red Light!" ... "Not if I can't help it!" *click*

1. To show off to your friends.

2. If you are running late.

And if they are both the case, like the above scenario... you don't have a choice, you have to use it.

...and every day to work.

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...and every day to work.

#2 covers that most of the time:

2. If you are running late.

:P

I think I might re-make this project again... using more infrared LEDs of course.

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