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Re: starship-design: Wirelss power transmission


Magnetic fields might not be such a good idea, since you might be erasing
hard drives and making metal objects move if the field is strong enough.  I
assume that the units are mobile, since if they were stationary, you could
just run some bell wire (available at radio shack) from a transformer to
the remote units.

Have you considered normal AM radio transmissions?  Depending upon the
amount of power needed, you might be able to use a local radio station
(milliwatts???)  rather than powering a speaker, you would be powering your

Old crystal radio sets were able to work without any external power (either
battery or wall plug) simply by converting the transmitter's broadcast
power into sound energy.

If you need more power, take a look at pirate radio equipment.  Provided
you stay out of the actual AM radio band (or other populated frequenccy
bands,) and don't actually transmit any information, you shouldn't have to
worry about the FCC.  I believe there are certain frequency ranges which
are reserved for applications like this.

Multiple local transmitters (or antennas) in each room may give you better
power reception at the units. (due to inverse square law)

Choosing the right frequency will be important, both from a regulation
standpoint, and a power transmission standpoint. (energy content of EM
varies with the frequency, such that higher freq. means more power.)

other ideas:

+ solar cells
+ rechargable batteries (assuming the units are mobile, perhaps they can be
designed to seek out a wall socket when their batteries are low)
+ thermocouples (depending on power needs and availability of a high
quality heat source.)
+ other energy storage devices - chemical, mechanical (mainspring, flywheel)

Good luck, and please let me know how this turns out. I am interested in
this as well, for applications in robotic self-replicating construction units.

At 07:18 AM 1/21/00 -0800, you wrote:
>I am in the process of completing a project that involves the use of 
>numerous remote units within a confined are to accomplish several tasks.  
>One thing that continuously bugs me is that I have to constantly replace 
>or charge batteries in the power hungry units.  Since it has more to do 
>with space travel than my project, I thought you may have some information 
>on Wireless Power Transmission in order to minimize use of battery power.  
>What follows is a short section of my notes, and I hope you can give me a 
>Notes on Wireless Power Transmission
>I keep finding entries that relate to high power microwave transmissions 
>which I really want to avoid.  I believe that the current designs are made 
>for long range transmission of very large amounts of power.  What we 
>require is a short range (within one building) transmission of a 
>relatively small amount of power.  The current designs are made to power 
>space structures or ships and colonies.  All we will require is the 
>transmission of battery power to a few remote units.
>One idea is the conversion of the building into the stator coil of an 
>alternator.  Inside each remote unit will be a rotor section which will 
>pick up the alternating magnetic field and convert it into an alternating 
>current.  This current can then be rectified and stored or used as 
>necessary by the equipment.  The design is simple, but I do not have 
>enough knowledge of electromagnetics to see if it may work.  What I would 
>like to do is use some resources to test a small scale experiment with 
>this idea in mind.  If my thought is correct, we will require a very low 
>level magnetic field, probably at a high frequency.
>Of course there are probably other methods of wireless power transmission, 
>but this one seems to be the most feasible and economical.  Also, it does 
>not involve potentially harmful microwaves.
>Thanks in advance
>Fred Reyes
>How to find me:
>AOLIM: Warlord400
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