induced current
i want to make an object that will glow when placed on top of a table that
i will also build. It can not have any batteries or other power storage.
It has to be less than a half inch cube.
my idea is to induce a current into them by using a set of coils embedded
inside the table, and a set embedded within the objects. If possible, I'd
like to have a microcontroller using that power, but just an led would be
fine for now.
This is essentially like a transformer, but without a core, and also
relatively distant coils.
how should i orient the coils? how should i wind them? can i find them
ready made? is this impossible?
thanks!
-raphael abrams
nyc
i will also build. It can not have any batteries or other power storage.
It has to be less than a half inch cube.
my idea is to induce a current into them by using a set of coils embedded
inside the table, and a set embedded within the objects. If possible, I'd
like to have a microcontroller using that power, but just an led would be
fine for now.
This is essentially like a transformer, but without a core, and also
relatively distant coils.
how should i orient the coils? how should i wind them? can i find them
ready made? is this impossible?
thanks!
-raphael abrams
nyc
Comments
You're building a very inefficient transformer, so I suggest that you begin
by experimenting:
Make a large coil, perhaps 1~2 feet in diameter, with many turns of
20~24ga. wire. Use enough wire to get the total DC resistance up to 4 ohms
or more. By doing this, you will be able to safely connect it to the output
of an audio power amplifier, which allows you to easily vary the drive
frequency (with an audio generator) and power level. Your secondary coil
uses smaller wire, perhaps 28~30ga., but as any turns as you can fit in the
available space. An iron or ferrite core (depending on drive frequency) may
help by concentrating flux. Add a rectifier diode and filter capacitor if
your load requires DC, but a plain old incandescent lamp wouldn't need them.
With this lashup, you should quickly get a feel for the possibilities. I
suspect that coupled power will vary quite a lot with coil positioning, but
you may be able to transmit enough power to burn out small lamps if you
feed in 100W or so. Higher drive frequencies will probably work better.
Some older audio power amps cannot tolerate full power continuous operation
above 10KHz or so, however. Good luck...
>i want to make an object that will glow when placed on top of a table that
>i will also build. It can not have any batteries or other power storage.
>It has to be less than a half inch cube.
>
>my idea is to induce a current into them by using a set of coils embedded
>inside the table, and a set embedded within the objects. If possible, I'd
>like to have a microcontroller using that power, but just an led would be
>fine for now.
Mike Hardwick, for Decade Engineering -- <http://www.decadenet.com>
Manufacturer of the famous BOB-II Serial Video Text Display Module!
>
> i want to make an object that will glow when placed on top of a table that
> i will also build. It can not have any batteries or other power storage.
> It has to be less than a half inch cube.
>
> my idea is to induce a current into them by using a set of coils embedded
> inside the table, and a set embedded within the objects. If possible, I'd
> like to have a microcontroller using that power, but just an led would be
> fine for now.
>
> This is essentially like a transformer, but without a core, and also
> relatively distant coils.
>
> how should i orient the coils? how should i wind them? can i find them
> ready made? is this impossible?
>
> thanks!
> -raphael abrams
> nyc
--
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Tom Rose
President ETA
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Whynot place the object under a laser above the table and sense the
placement of a translucent object turning the laser on.