Prank: Set off radar detectors

Now im not completely sure how legal this is, or if it even is legal, but my teacher today was talking about a little device someone made for him, that sets off people's radar detectors on the highway, and they slow down. It would be a rather funny prank to pull on someone speeding in a fancy sports car, with their brake lights coming on. Anyways, if you know of a schematic of this, or how to build one let me know, as Ive looked on google, and cant find anything. If it is illegal, well, just let the topic rest. Thanks!

I would imagine it's illegal because you're transmitting without a licence?.

But all you would need is a small microwave transmitter on the correct frequency, and the detectors are pretty crude.

Well, Im assuming your just using RF signals, and at the moment, I am in the process of receiving my HAM/Amateur radio license, which lets you transmit on from HF to UHF freqs. So, idk...lol

Pranks are done by stupid little kids who don't think about consequences.

The speeder's radar detector goes off by your device, he slams on his brakes and causes a huge traffic accident with people being maimed and killed.
Please grow up.

IF we could figure out what frequency range, then id be able to tell if its legal.

Radar detectors used to be set off all the time by the sensors used by automatic door openers for shops and things.

wow, pretty rough there. They dont slam on their brakes, just slow down, and common sense would ensue in things like these. I mean obviously it would be completely dumb to to use it on icy roads conditions. You use it when minimal cars are around. But yeah, just wondering, as ive seen people do it.

Yeah, thats what our professor said, they used a garage door opener, and modified it. I see no difference in using one, vs. a cop.!?!?!?

Some drivers cause accidents when a little squirrel runs across the road.
Sure they slam on the brakes when their radar detector alarms.

I've done this before. I started with a surplus X band Gunn diode waveguide mount, which is a small chunk of waveguide split down the middle with a gunn diode mount on one side and sometimes a detector diode on the other side. This is the hard part already built. In my case i was building a speed measuring device, so I added more circuitry to form a complete receiver. One day, after the project had long since been completed, I was annoyed at the speeders roaring down my street, so I took my little waveguide device, sat it on the tailgate of my truck out at the end of the driveway and wired a pushbutton switch in line with the DC power. Then as drivers came down the street I would push the button and watch them hit the brakes. Great fun. Believe me I had no sympathy for those that felt it necessary to go into a four-wheels-locked panic skid on my 30mph residential street.

X band is around 10.5 GHz. Back in those days part of my job was repairing radar guns for the police department that I worked for. I sometimes would test the finished units by taking them out on my off hours. I would park on the side of a high speed but not too busy section of road and operate the unit hanging off the side of my driver's side window. You should have seen the looks of passing motorists as they wondered why the police were now using 240Z ghost cars.

Here's an example of the hardware I used:
**broken link removed**

You need an antenna, but you can make a horn antenna by soldering some pcb material together.

RadioRon said:

Believe me I had no sympathy for those that felt it necessary to go into a four-wheels-locked panic skid on my 30mph residential street.

Click to expand...

Did the grannies driving behind the speeder survive rear-ending him and each other?

audioguru said:

Did the grannies driving behind the speeder survive rear-ending him and each other?

Click to expand...

Yes, happily they did.

I have seen grannies driving their electric wheelchairs faster than 30km.

*cough* cell phone jammer *cough*

My section of Canada has a new law that condemns using a cell phone when driving.
Everybody continues to chat on the phone while swerving around on the road and going thru red lights.

The traffic cops aren't looking. Maybe they should jam cell phones.

audioguru said:

My section of Canada has a new law that condemns using a cell phone when driving.
Everybody continues to chat on the phone while swerving around on the road and going thru red lights.

The traffic cops aren't looking. Maybe they should jam cell phones.

Click to expand...

The cops may be on their cell phones and so don't see these perps.

The irony in these laws forbidding cell phone use in cars is that cell phones were originally invented for use by people in cars. That would be back in the '80s I guess.

If you rear end someone, it's your fault no matter how hard they braked. If you can't stop in time, you are driving too close.

audioguru has a point though, motorised vehicles should never be the subject of pranks. There are enough tragic deaths and serious injuries on the roads as it is.

Having said that, a real "safety" camera could cause the exact same reaction.

mijenak said:

If you rear end someone, it's your fault no matter how hard they braked.

Click to expand...

True, tailgaters suck. If they are too stupid to realise that leaving a 1 second gap instead of a 5 second gap will only get them home 4 seconds faster then they shouldn't have been given a licence.

mijenak said:

Having said that, a real "safety" camera could cause the exact same reaction.

Click to expand...

A British city (I think it was Swansea?) has just become the first to dump fixed 'safety' camera's - their statistics show they have caused an INCREASE in road accidents, rather than a decrease.

Also, and something I didn't know, the local council have to pay for, maintain, and administer the cameras, yet the fines from them go solely to the government. Swansea say they can better use the money it costs elsewhere, to actually improve road safety.

Just because something is not illegal does not mean it is acceptable or even defensible. You could escape criminal prosecution but still be held accountable in a civil court in a wrongful death lawsuit.