Traffic signal tripping device

[blair]

Anyone tried this and determined that it actually works?

http://www.jcwhitney.com/autoparts/Prod ... 11/s-10101

I'm skeptical.

The fact that an object is magnetized shouldn't increase its effect as a concentrator of magnetic lines of flux coming from an current loop. In fact, if it's magnetized enough it will be saturated and its ability to do so will be limited.

What it might do is, as you move into the loop, it might induce an electromotive force in the loop. But I don't know if the loops are set to detect both increases and decreases in their loop voltage, so it might not work on loops polarized the wrong way (though it might if they are standardized). And you'd have to be moving, so the changing magnetic flux from this device could create the EMF in the loop.

On the other hand, it's so close to your bike that most of its magnetic lines of flux will be concentrated in your bike's ferrous parts, leaving very little to reach down into the ground to interact with the loop.

So, from a theoretical standpoint, this thing looks like bollocks. But maybe adding an extra slug of a high-permeability material to your undercarriage lets the loop's magnetic field "see" you better. For that, this thing is awfully small, although some of the newer supermagnetic materials are pretty impressively much stronger than the old ones...

See why I need objective, empirical data? And a long ride in the sunshine followed by a cool margarita in the shade with my dog? And another girlfriend?

[Hawking]

I'm curious as well. I live in an area where all of the traffic lights are triggered, not timed, so I could sit there for wuite a while until a car pulls up behind me to trip the sensor. On occasion, I've even gotten off the bike, walked to the side of the road, pushed the pedestrian button, walked back to the bike, gotten on, put up the sidestand, put it in gear, and still had to wait a while for the light to change.

I's be curious to see this thing in action.

*Edit:

OK, so there's one on the way, via UPS. I'll post the results, with and without, for some empirical data.

[DivideOverflow]

I know some people that use them. I can say at least the one my friend has works... he will get lights to turn that I cannot on my bike.

http://www.harley-performance.com/signal-changer.html

[allawybiker]

but then where do you put your wallet? or can u carry your laptop with you? it sounds like the magnetic field is very strong and could damage these!

[Randy]

Are there any tricks to get the ligts to change. Sometimes the sensors seem to pick me up fine, other times I wait forever.

[ronboskz650sr]

I stop right at the intersection of two wires, and it seems to sense me. Intersections where I didn't trip them before are tripping now with this technique. I used to stop just off center and a couple of feet back. This way requires you to get forward in the lane, and put your wheel near or over the stop line if there is one, but it trips the signal.

[blair]

The sensor is an electromagnet coil buried in the ground. When you put paramagnetic material in the coil, you increase its inductance and change the frequency of the oscillating circuit that contains the coil. If the "slug" can't be inside the loop (and unless you can sink your bike halfway into the ground, it can't), the best place to put it is as close as possible to the wires, to minimize the distance and maximize the number of flux lines that are cut. Laying a steel bicycle frame down on the pavement directly over one edge of the coil actually works. Aluminum, not so much.

So aim for the edge of the loop if you know a light has to be tripped.

The other day I almost parked the bike and ran for the walk button, but just as I thought of it, the DON'T WALK sign started blinking, so it had timed out, after like 90 seconds.

[DivideOverflow]

but then where do you put your wallet? or can u carry your laptop with you? it sounds like the magnetic field is very strong and could damage these!

You put the thing on the bottom of your bike, it wont affect you while riding... they just warn people with pacemakers for when they are handling it and putting it on the bike.

[keysman]

I have never had a problem triggering the signals myself.

[poppygene]

My bike has a steel frame and is a fairly substantial machine, relatively speaking, so I don't usually have much trouble tripping a signal. However, there is one particular signal that defies me and, as luck would have it, it's the one at the entrance to my neighborhood. I'm gonna have to try one of these gadgets. Waiting through several cycles for a car to pull up behind me and trip the light is no fun.