Single wire power transfer... / General Science and Electronics / Forums

Forums

4hv.org :: Forums :: General Science and Electronics

« Previous topic | Next topic »

Single wire power transfer...

1 2 next

Move Thread

LAN_403

Patrick

Tue Dec 18 2012, 02:58AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Is it possible to send 4 to 5 volts at 100ma through a single conductor?

i remember the simple diode radios that were effectivly self powered from the rectified radio wave, i made as a child. So i was wondering if it would be possible to send AC at 10-100kHz through a rotating metal shaft then rectify it and smooth it with a cap? or am i crazy?

the power is to be used for a small MCU/PIC and laser...

...

Tue Dec 18 2012, 04:15AM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

It would be possible, although I do not thing that having a 1/2watt of RF power radiating through your drone will be the best idea. You would also need some sort of ground plane to couple power through (presumably the frames of the drone and transmitter would work for that).

Could you use a rotating transformer? If you can find one, VCR's have nice rotating transformers in the read heads and good bearings, there are also plenty of channels so you could send data back down as well if necessary.

Josh Campbell

Tue Dec 18 2012, 05:11AM

Registered Member #5258 Joined: Sun Jun 10 2012, 10:15PM
Location: Missouri - USA
Posts: 119

Sounds like you need to brains storm on other methods of power transfer to a rotating head. Does any data need to flow to or from the rotating laser, or just power to it?

Gogo gadget brain storm: (note brainstorm may contain spurious idiotic ideas)

-A triangle of rotating solar panels receiving light from internal source(s), smoothed with a cap. Would need to series a few small panels to reach 5V or use a simple boost converter.

-Circular traces on a base circuit board. Soft tabs (metal type... not sure) protruding from rotating head that drag on the traces.

-A stationary neodymium magnet and one or more coils that pass by the magnet, smoothed and boosted as needed. (Very feasible, just like the shaky shaky flashlights.)

-A zero-point module on the rotating head. (My favorite so far.)

-Ground the motor shaft, this provides ground reference to the rotating circuit. Have a piece of spring metal that hits a post as it rotates, this post has a voltage of your choice on it. Smooth, boost, etc.

-Put small generator on the rotating head with a rubber wheel that rolls on some surface. You know the rest.

-Install a gerbil wheel in the rotating head, let the gerbil sit in the pilot's seat. Watch as you're creation flies without LIDAR because the gerbil wheel is a dumb idea but the gerbil in the cockpit was a good one.

-Scrap a DC motor brush assembly, mount on the top if mounting below is impractical due to the already spinning motor.

-Something with magnets... I think that is the key if you don't want touching metal parts.

-A small windmill on the rotating head.

-A small rechargeable battery on the rotating head, a couple miniature li-po's maybe. Charge when stationary. Not ideal but easy to implement.

-Place a pelter heat junction vertically on the rotating head with a heatsink on one side, paint the other side black. The fins run horizontally so the wind will blow over them as the head turns. Pulse a high power laser at timed intervals to only hit the black side. Each junction only putouts about a volt at a respectable current, so stack 5.

-PIEZOELECTRIC ENERGY HARVESTER

I'm done. :)

Patrick

Tue Dec 18 2012, 05:59AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

2bytes wrote ...

-Install a gerbil wheel in the rotating head, let the gerbil sit in the pilot's seat. Watch as you're creation flies without LIDAR because the gerbil wheel is a dumb idea but the gerbil in the cockpit was a good one.

only communists use Gerbils in scientific experiments, in the west, we more properly use hamsters. like civilised people. this is the best idea yet, a hamster powering and flying my drone, no SLAM model needed! just peanut butter!

EDIT: on a more serious note, the VCR idea has me intrigued.

Mattski

Tue Dec 18 2012, 07:16AM

Registered Member #1792 Joined: Fri Oct 31 2008, 08:12PM
Location: University of California
Posts: 527

You recall the recent thread on single wire power transfer?

It can be done, but you need a capacitive return path for the current . If you transmit at high enough frequencies where you can get good radiative power transfer then you don't need a return path, but radiative wireless power is not a particularly simple or economical approach. There would also be regulator issues there.

Andy

Tue Dec 18 2012, 07:20AM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

You might be able to use rfid type setup

Ash Small

Tue Dec 18 2012, 12:37PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

I'd look into a rotating coil/coils, with fixed magnets, although the idea of having a hamster pilot a quad-copter powered by a Tesla coil does sound intriguing.

Proud Mary

Tue Dec 18 2012, 01:29PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

You might look at some army surplus outlets for guided missile control wire, which comes in spools. It contains a mix of insulated conductors and steel wire and is very fine but strong. I believe it was used in Semi-Automatic Command to Line-Of-Sight wire-guided anti-tank missiles like MILAN, and more recently, BGM-71 TOW.

Patrick

Tue Dec 18 2012, 05:33PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

I may just use carbon brushes for power and 433MHz wireless for sgnal. and for the initial prototype ill use zinc-air batteries.

Electra

Wed Dec 19 2012, 12:18AM

Registered Member #816 Joined: Sun Jun 03 2007, 07:29PM
Location:
Posts: 156

Couldnâ€™t you use a movable mirror rather than rotate the whole assembly,
Some old types of barcode scanners used a rotating hexagon mirror for scanning.

If you have to rotate the electronics to get 360 coverage, but the speed isnâ€™t so high then yes mechanical slip rings would be simplest for power.
It might be possible to do some king of rotating optical link for data, along the axis of rotation if you have space above it.

As for rotating inductive transformers you might need you use some kind of modulation for binary data signals.

1 2 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob