A few random questions

[zachtheterrible]

These are a couple of questions that I have been wondering at for quite some time. I figure I might as well ask 'em all in one thread instead of starting a couple :lol:

1. Why does the human body produce a 50/60HZ hum?

2. What are those little things that you see on top of stoplights? They are probably about 3 inches tall and an inch wide, in a cylindrical shape. They are black. They have two little pieces of metal sticking out, pointing towards the road that the stoplight that they are on is controlling; it looks like they shade some kind of sensor from the sun. My best guess is that they are IR sensors that turn the light green when an ambulance, fire truck or police car points a control at them if they are in a rush.

A friend of mine told me that at night you can flash your headlights at them twice and it will turn the light green. Sounds like a load of crap to me :lol: . I have yet to try it.

I know I have more. Ill write them down as they come :lol:

 

[williB]

1) i believe that is the body picking up Electromagnetic waves from the Mains power in your house..but i dont have a portable scope to test this theory ,( away from any powerlines ) ...

 

[chemelec]

2. What are those little things that you see on top of stoplights?

Or they may be Cameras.

In Canada, Most major intersections have cameras to catch guys going through Red Lights.

Usually they use an RF Transmittter for the Emergency Vehicles.

 

[audioguru]

2) Wouldn't it be neat to have one of these IR transmitters in your car or truck to give you green traffic lights?
http://www.themirt.com/

Zach, buy one and see if it works. Then take it apart and tell us how to make one.

 

[Klaus]

Isn't it amazing that an "electronics god" does not know the answer to these simple questions
:wink: :lol:

The enviroment in every modern city abounds with electricity. Either 50 0r 60 Hz, depending where you are located. So, is it really unusual that out bodies pick up some of this field as we move about?

If you were to try to measure this out in the desert, using a battery powered oscilloscope, your observation would be the heartbeat only if your scope is sensitive enough.

While I'm not familiar with Californian 'stoplights' (we call them "traffic lights" here) I have a theory. Now, here in Australia there are sensor coils located under the road surface at every city traffic light, they sense the presence or absence of a vehicle. This initiates the traffic light sequence after hours and adjusts its timing during business hours. After hours the lights are usually favoured towards the main road and would only change for cross road traffic if the sensor coil senses a vehicle.

Now, Californians, doing things differently I'm led to believe :wink: might use sensors on top of the traffic light poles to sense vehicles . It would seem a plausible explanation if, as you say, these tubular thingies are on EVERY traffic light pole. Don't ask me what method the top mounted sensors employ, the under surface coils are inductive proximity sensors, sensing lumps of metal just like a metal detector. They do not work for pushbikes and have troubles with motor bikes unless the driver is positioned at the centre of the coil (the road is marked where that spot is).

Klaus

 

[zachtheterrible]

Isn't it amazing that an "electronics god" does not know the answer to these simple questions

Please to be reading my signature :lol:

I actually assumed that this was the answer but was not sure . .. so there! i wish there was a smily sticking out its tongue :wink:

2) Wouldn't it be neat to have one of these IR transmitters in your car or truck to give you green traffic lights?
http://www.themirt.com/

yaay i was right. now i can prove my friend wrong :lol:

When the fire truck approaches within 1,800 feet (line-of-sight) of a preemption-equipped traffic signal controlled intersection, the preemption detector (normally mounted on the cross-arm that suspends the traffic signal) "sees" the fire truck’s preemption transmitter and locks onto its flashing strobe.

is there such thing as an infrared strobe?

While I'm not familiar with Californian 'stoplights' (we call them "traffic lights" here) I have a theory

stoplights, traffic lights . . . tomato tomata :lol:

actually california does have inductive sensors under the pavement. You can see the lines from where they took a saw and cut the pavement and then resealed it.

Thanx guys, you have saved me many sleepless nights :lol:[/quote]

 

[audioguru]

Now, Californians, doing things differently I'm led to believe :wink: might use sensors on top of the traffic light poles to sense vehicles

The sensors on traffic lights don't sense vehicles. They sense a matching IR transmitter on fire trucks. Then the fire truck has green traffic lights everywhere it goes. As electronic gods, Zach and I want one too. :?

Cities are afraid of mayhem if everyone had one, so the newer sensors are programmed to respond to a code. Then us electronic gods will hack the code. Right Zach? :lol:

 

[zachtheterrible]

ya, i bet i could toss some sort of receiver up there and when someone goes through it would store the code, then I WILL BE IN CONTROL OF THE CITY!! AHA AAA HAAA HAAAA!!

That thing says that it uses a strobe. Is there such a thing as an infrared strobe? Or is it just in layman's terms, referring to an IR LED array?

 

[audioguru]

When they say strobe, I think it just blinks at a certain frequency.
They must be using an array of many LEDs to get the very long range without tight focussing.

They might use a form of rolling code, like in garage door openers, that changes each time and is pretty hard to beat.

I read about traffic lights in Google and there are some remote controllers that give a fire truck a single green light, with red lights in all 3 other directions. A white flood light tells the driver of the fire truck that he has control of this intersection. I've never seen it.

Zach, let's find our old fireman's hats! :lol:

 

[zachtheterrible]

Zach, let's find our old fireman's hats!

haaa haa ha

I don't see how they could use rolling codes. Rolling codes require that the transmitter and receiver be synchronized. Every time that the code is sent, the transmitter and receiver switch to a new code for next time. Since there are multiple transmitters and receivers, it would be impossible to synchronize all of them without there being a radio connection or something.

Just makes it all the easier for us electronics gods. I wonder if this there is a law governing this??

 

[captainkirksdog]

Firetrucks used to have what were called, "wobble lights". It was a lamp mounted in a deliberately wobbly fixture and it was it's NON-synchronized flashing that tripped the traffic light sensors. And yes, flashing your headlights at just the right rate and distance did work. I drove a '64 panhead Harley with a wobble light above my regular light just because I hated to put my feet down! Sadly, most city morons..er managers have had all the systems changed. The newest technologies for Public Safety vehicles include signature-coded Bluetooth and/or ZigBee wireless.

 

[zachtheterrible]

How can they use any kind of radio signals? Wouldn't it open up ALL of the green lights? With infrared, you could "point" at the light you want green.

 

[moody07747]

2) Wouldn't it be neat to have one of these IR transmitters in your car or truck to give you green traffic lights?
http://www.themirt.com/

Zach, buy one and see if it works. Then take it apart and tell us how to make one.

ive seen those while searching today and they sell for about $300

and its probably a $5 circuit in there
would be kool if we could get a wiring sheet for one of those

i tried to find one of those MIRTs on ebay but the count is zero

 

[moody07747]

i wish there was a smily sticking out its tongue

here is one that i know of

**broken link removed**

the link is
**broken link removed**
put in the **broken link removed**

 

[pittuck]

here in the uk we have traffic lights

lol, even better is that on my closest set we have a system which was being tested, there are IR sensors facing down which sense when people are at the side of the road.

Now, it does not change the lights, nor does it do anything of real use, but its a cool idea to have a sensor there to do that.

But if someones car had a IR sensor to allow them to pass lights in california etc. then in the UK ur never gonna get anywhere!!!!

 

[mechie]

Wouldn't it be neat to have one of these IR transmitters in your car or truck to give you green traffic lights?
http://www.themirt.com/

I am in awe of the "demonstration" you can download and "try out" - you had better not mount that thing too low or the things it shoots out of the front could have a cyclist's head off :!:

yaay i was right. now i can prove my friend wrong

UK traffic lights (cross roads, junctions, etc., even temporary roadworks) usually have a rectangular box on top of them, shrouded from the sun and pointing down towards the oncoming traffic, these DO sense car headlights - when there is little traffic (night time?) these sensors are just one more input to the controller to keep the traffic moving - I have used 'full beam' headlights to make traffic lights change in my favour.
Busy junctions will ignore this sensor in favour of the inductive loop and/or a simple time program.

When the fire truck approaches within 1,800 feet (line-of-sight) of a preemption-equipped traffic signal controlled intersection, the preemption detector (normally mounted on the cross-arm that suspends the traffic signal) "sees" the fire truck’s preemption transmitter and locks onto its flashing strobe.

There are few junctions here in the UK that allow a 1,800 feet line-of-sight. Our emergency vehicles just hit the sirens and 'crash' the lights, simple and effective - we know they have absolute right of way and keep out of their way.

 

[Nigel Goodwin]

UK traffic lights (cross roads, junctions, etc., even temporary roadworks) usually have a rectangular box on top of them, shrouded from the sun and pointing down towards the oncoming traffic, these DO sense car headlights - when there is little traffic (night time?) these sensors are just one more input to the controller to keep the traffic moving - I have used 'full beam' headlights to make traffic lights change in my favour.

It's a popular misconception, the boxes on top are microwave doppler radar detectors, they detect a vehicle approaching the lights and take account of it.

 

[zachtheterrible]

I must say im very surprised about that headlight thing. Seems funny that it only works at night :lol:

 

[audioguru]

Hi Zach,
They do odd things in the UK. They drive on the wrong side of the road. I think they drive at night in the city with their "parking lights" on. Have you ever used your parking lights in the US? I have never used mine in Canada. Some people here do, maybe from the UK, and they can't see where they are going at night. :lol: :lol:

 

[zachtheterrible]

What the deuce are parking lights? The only lights that I know I have are low beams, high beams, blinkers, brake lights, and backup lights.