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Free electricity for a bicycle headlamp Answered

A really good bicycle headlamp needs quite a bit of electricity to make it bright and last a couple of hours. A dynamo requires extra leg power to operate. Yet, there are power distribution lines along the roads where I ride and they emit electro-magnetic lines of force. Imagine a coil of wire on the bicycle that follows the triangle portion of the bicycle frame and it receives these lines of force, converting them to a low voltage AC current. That current would then be passed through a bridge rectifier and a voltage regulator to charge normal size flashlight cells powering the light. Technically, it is probably illegal. Certainly it would be if you were using a coil of wire on your lawn positioned under the power lines to power your house. If it could be done safely, the power company would have a hard time tracking you. It is probably impractical, but it is interesting to ponder.



6 years ago

Would be interesting to see the results of these tests, you may also find resistance from the power company though. Interestingly Google are paying more and more attention to green energy - specifically Solar, with the backing of big brands like them an 'out-of-the-box' energy crowdsourcing idea like this may become a possibilty. Free Wifi being rolled out in some cities being a case in point.

More on Google's green investment here Google solar power

Phil, this is interesting to me. My 2 cents worth may seem negative, but I hope you find a way. I don't think the power available here will provide any useful voltage, and will be on the order of microvolts, millivolts with luck. It's going to take 700 millivolts just to turn on a rectifier. You certainly should not have to worry about personal safety. A transformer will need many turns on the secondary, and if the wire size is too small it will introduce significant resistance.

It is tough trying to pick up appreciable power without resonance or extreme proximity to the source, and preferably both. Proximity is definitely out! Attaining resonance at 60 Hz with the ability to transfer significant power seems doubtful to me, but you may be the man who amazes us all.

I don't think I'd worry about this being theft. If you get this to work and produce significant power, you will be able to buy the power company and tell them too shut up.

Thanks. I will have to think about whether I actually try this or not.

If you have a degaussing coil, hook a DVM to it and take it for a ride. Simple test.

I do not have a degaussing coil. I thought I might measure the circumference of the main tubes and headset in my bicycle frame and make a coil form to that dimension. Then I could begin laying up turns of wire to place near the power lines above our back property line. There is really no need to make a test while moving because the alternating electrical field from the power lines will rise and fall by itself. I would probably wait until I can get my hands on some "free" enameled wire.

Locate an old CRT-type TV or monitor and remove the degaussing coil from it. You now have a free degaussing coil. Hook up the meter and test to see what kind of voltage you can expect to develop. I expect you will measure such a low voltage you will give it up, but if the voltage is a volt or so, maybe you can consider using a step up transformer.

The free degaussing coil has a substantial amount of free enameled wire, too. Get a degaussing coil out of any CRT or monitor you see heading for recycling or the landfill. Some deflection yokes are wound in such a way that the wire can be removed without major effort, but many are "formed" into shape by a varnish-like coating that glues them together pretty well. Be careful working around those CRTs, of course. Discharge them, and gas them by breaking the nipple at the socket.

I agree with Kiteman, Phil. Your idea is very good, only needs to be tried. I think the output will be very poor, but I've been wrong so many times that this might be only one more!

I like this article about air energy.

Thank you, Osvaldo. I will check the article about energy. I think a big problem with my idea is that the power company usually regards such things as theft.

Hmm, I'm all for free power but since this is probably - as you say - technically illegal (and if it isn't, the Electricity companies will either find a way to make it so, or raise their prices even more - or both, more likely), I think you'd be better off looking into nagutron's 'ible here:


and vbnicolau's 'ible (which nagutron also links to):


as these probably aren't anywhere near the weight you're thinking of in your reply to kelseymh, and shouldn't require as much extra effort as a dynamo.

I think that your receiver would have to be too big to be practical.


Just now I was using some very general terms to search the Internet. It seems there are some folks who regularly propose things like this, but with little hard data resulting from it. One interesting article speaks about pulling electrical current from the air near power transmission lines with only an umbrella shaft, but that was during a time of very high humidity. Another article linked there concerns using coils to collect "aetheric energy." Not surprisingly, the name of Nicolas Telsa appears in some of these articles. Still, the results appear to be anything but completely predictable.

Interesting, thanks.


This is a very interesting idea! My suspicion is that the energy density that far from power lines (at least 30 meters) is going to be too low to generate a useful voltage (EMF), but that's just a guess.

This is crying out for an experimental test :-) You'll need a lot of turns in the coil, which may make it too heavy for regular use on a bicycle. Please, if you have the interest, give it a shot!

I have heard of people stealing electricity from the power company by placing a large diameter coil on the ground in their backyards and connecting the ends of the wires to their household wiring. It apparently works, but the distance between the lines and the coil would be less than 30 meters, perhaps 10 to 15 meters at the most. A coil mounted on a bicycle would be nearer at times and farther at other times to the power lines. If a power level meter could be added to the circuit, it might even be possible to have a coil in multiple sections. When "output" dropped, flip a switch to engage another section or two of the coils. Since the amperage requirements would be quite low, I am thinking #26 gauge wire would suffice. A suitable coil made of it should not add more than a kilogram or so of weight to the bicycle.

I was all set to declare this wouldn't work, but...

You know what, why not fit a coil onto your bike, connect the ends to a multimeter, and then see if you get any usable power as you cycle around.

I certainly doubt it could power lights directly, but maybe you could persuade it to charge a battery to run an LED lamp?

Your thought was mine, too. Some experimentation would be needed to hit upon the correct number of turns (of wire) in the coil. I would not want to be surprised by enough voltage to get a nasty shock. Connecting the coil to a multimeter and keeping hands far away would be a safe test. My thought was simply to extend the charge in the batteries, not to power the light directly, nor consistently. Still, some power lines are higher on the distribution chain than others and would have a stronger electromagnetic field producing a different and higher voltage in the coil.