Coupling power wirelessly

HollyMinkowski

I'm thinking of building some little fun project and instead of sticking it
into an ordinary project box I am considering encapsulating the whole
works inside a block of clear plastic.

I have this liquid plastic that gets super hard after you add a little bit of
a 2nd liquid to it.

I can use those 100 farad 2.5v capacitors for power but I will need to
have some sort of wire coil very near the bottom surface of the plastic
cube and send magnetic pulses to it. Then I would need to somehow
convert the induced current pulses into the proper dc V to charge the
caps. I figure I could build the charger into a cute base that the plastic
cube could then sit on....this would power it 24/7 and also allow the device
to be removed from the base and still run for a time on the power
stored in the caps.

Anyone here ever done this kind of wireless power transfer?
Any pointers or links to circuits you recommend?

With the high cost of really nice project enclosures I figure that encapsulating
will be no more expensive, and it also seems like a cool idea.

There is a stinky chemical that can turn the clear
plastic back into a liquid if you just drop it into a container of it and leave it awhile.
No idea what that would do to the electronic parts though, and it might
take the plastic cover off the chips and the caps...I just don't know, guess I
could test it.

EDIT: I just had the thought that building the circuit and then dissolving
the plastic off all the parts, LEDs, chips..etc and then encapsulating it
might make for a very interesting looking bunch of naked parts inside
the clear plastic
I wonder if LEDs will still work without being inside the clear plastic that
normally covers them? and I wonder if the light would end up being just
a tiny spot too bright to stand to look at.
If you assembled all the parts with wires and used no circuit board it
would look like the parts were just floating in the plastic...that might be cool.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Some mornings I wake up cranky.....but usually I just let him sleep in -

Post Edited (HollyMinkowski) : 8/23/2009 6:52:57 AM GMT

T Chap

Check out the toothbrushes that charge off a base. I forget the brand but mine sits on a base, charges with no electrical connections. Must be coils.

WBA Consulting

Braun Oral B Cordless Toothbrush. I have a dead one in my "project box". It has a single AA NiCad battery inside. I have been wanting to use the setup to make a charging circuit for about 2 years. I also bought an RFID mouse from cyberguys about 2 years ago. It used the RFID frequency concept to power the mouse itself. The mousepad it came with had a 5" diameter flat coil that transferred the energy to a flat coil in the base of the mouse. In my haste to reverse engineer the mouse portion of the circuit, I broke one of the parts which left the mouse unusable and the part un-identifiable. Anyhow, was a cool concept.

www.cyberguys.com/product-details/?productid=11135


www.oral-b.com/en-US/products/default.aspx#f=&overlay=&s=&rd=

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Andrew Williams
WBA Consulting

HollyMinkowski

Wish I had that broken toothbrush to take apart

I just lashed up a qwik-n-dirty pair of coils and a pulse circuit driven by an
Atmega168...pulsing the coil with 5v using a single pn2222 and you can at least
detect the pulses in the 2nd coil on a scope...but they have to be really close!

I think the coils need lots more windings and the current pulsing them needs to
be much higher... and I fried the transistor when I tried making the pulse longer
than 1ms... so a better transistor is a must.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Some mornings I wake up cranky.....but usually I just let him sleep in -

HollyMinkowski

Wish I had that broken toothbrush to take apart

I just lashed up a qwik-n-dirty pair of coils and a pulse circuit driven by an
Atmega168...pulsing the coil with 5v using a single pn2222 and you can at least
detect the pulses in the 2nd coil on a scope...but they have to be really close!

I think the coils need lots more windings and the current pulsing them needs to
be much higher... and I fried the transistor when I tried making the pulse longer
than 1ms... so a better transistor is a must.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Some mornings I wake up cranky.....but usually I just let him sleep in -

HollyMinkowski

I wonder why that posted twice?

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Some mornings I wake up cranky.....but usually I just let him sleep in -

BradC

You really want to be driving that coil with AC rather than pulsed DC. You will get a much better result. You probably saturated the coil with a pulse longer than 1ms which would drive the coil current right up and take out the transistor.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
lt's not particularly silly, is it?

ElectricAye

HollyMinkowski said...
....
If you assembled all the parts with wires and used no circuit board it
would look like the parts were just floating in the plastic...that might be cool.

If you know what the refractive index of the casting plastic is, you could probably find a sheet of clear solid plastic to match. Then you could drill holes in the solid plastic to fit your parts, and when you cast everything in the liquid plastic, the solid plastic self-made perfboard might appear to disappear. The solid has to be pretty clean, though, and not burnt by your soldering iron to match the indices. There are also a number of index-matching silicone oils you could play with if you want to keep things in a liquid, or even gooey, state. It's just a thought if you get into trouble with your air-wire scheme.

Franklin

A bit dry but there is some good info here www.araa.asn.au/acra/acra2006/papers/paper_5_18.pdf

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Stephen

HollyMinkowski

@BradC

Thanks for the advice about ac.
That might be easier to use, I could perhaps get the coil out of an old
ac transformer and just put that in the base? If I could do that then the
base would have nothing but the coil and fuse and hook directly to 120vac.

Then I could hook the coil in the plastic block to a full wave rectifier, capacitor
and then a voltage regulator. I could experiment to find out how many turns I
would need on the coil to get into the proper voltage range...I guess the voltage
would also vary with the distance the coils are apart.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Some mornings I wake up cranky.....but usually I just let him sleep in -

stamptrol

Holly,

Traditionally, the primary and secondary were wound literally over each other. Very difficult to separte the windings. Now, many small transformers are wound on two separate bobbins that are stacked onto the iron core. Makes it easy to separate the secondary to put in one part of your device. Still a bit of a job to have the iron core be in close contact when its time to charge. Also, don't operate the primary coil without a complete magnetic circuit.....will burn up in seconds. Build in a switch that only closes if the core halves are in close contact with each other.

A second way to power a portable device is to build solar cells into the device and have it sit on a strong light in the base unit.

Cheers,

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Tom Sisk

http://www.siskconsult.com
·

erco

Check http://www.woot.com TODAY ONLY (Aug 24) for an inductive charger with 2 batteries. $20 shipped.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
·"If you build it, they will come."

HollyMinkowski

Thanks for that link erco

And thanks to everyone for all the advice!

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Some mornings I wake up cranky.....but usually I just let him sleep in -

Manetheren

You also might look at the newer style fryers as they have a magnetic type plug that easily disconnects from the fryer.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Tia'Shar Manetheren

hinv

Holly: You can't take the top off of the chips and cote them with clear plastic and still have them work. The reason that transistors are always encased in black is because light is a suitable substitute for base current, meaning they fire in the presents of light.
Also there are very fine wires in many LEDs and ICs that could easily be broken off.

Have you thought about a solar option. Then you could just have a light bulb for a base. Bases, bases, bases everywhere! Of course, it would depend on your power requirements and size of case, but considering you are already talking about running on capacitors, you might be able to make a few solar cells work.

BTW, do you mind giving us the source for the hard plastic stuff and the 100Farad capacitors?

SRLM

I like the solar option too. Then, if you take the module somewhere, you can just put it upside down for a while and it will charge. With the inductive charging, you're as tied to the base station as a plug.

CounterRotatingProps

HM said...
There is a stinky chemical that can turn the clear
plastic back into a liquid if you just drop it into a container of it and leave it awhile

Holly, what's the solvent chemical?

What's the two part clear stuff (the 'plastic')·? Is the '2nd liquid' MEK?

(I work a fair amount with things like this.)

Depending on how good of a result you want, you might have to make a test pour about the size of the cube with nothing in it - to see if you get bubbles, or to see if it gets hot.·· Certain two-part materials, such as epoxies,·are 'thermo set' - and even small amounts confined can generate a good amount of heat. For example, a dixie cup filled only 1/3rd full with fast set epoxy can get so hot that the cup catches on fire in <5 minutes. (how do I know that ? )

Fun sounding project!

- Howard



▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔

xanatos

The "stinky chemical" - is it Acetone or Methylene Chloride? Both of those will liquidate plastics until they evaporate out of the solution. For fun: Drop a styrofoam cup into acetone and watch how tiny the styrofoam mass really is! Seems to me there's gotta be a way to recycle styrofoam plastic... but I digress.

Dave

Unknown

xanatos said...
The "stinky chemical" - is it Acetone or Methylene Chloride? Both of those will liquidate plastics until they evaporate out of the solution. For fun: Drop a styrofoam cup into acetone and watch how tiny the styrofoam mass really is! Seems to me there's gotta be a way to recycle styrofoam plastic... but I digress.

Dave

Methylene Chloride may also be called Dichloromethane.· It is poisonous or toxic and is a paint stripper.· It is classified as a hazardous chemical.
·

erco

MC is a known carcinogen now. Long ago we used to use it in our shop, but no more now that everything has·to have custom warning labels. ·I know old timers who used it to wash paint off their hands, Yikes. We still have access to MEK for solvent bonding, but that stuff is probably on the way out, too. Nasty fumes.

I'm guessing Holly's hardener may be MEK peroxide.


▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
·"If you build it, they will come."

$WMc%

MEK peroxide is used to Hardin polyester resin. This is the resin used in lower cost fiberglass construction.


__________$WMc%___

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
The Truth is out there············································ BoogerWoods, FL. USA

HollyMinkowski

www.castolite.com/
This is a liquid plastic that I have used at home for arts and crafts...the stuff at work
seems just the same but has different names on the cans.


If I remember correctly (I'm still on short holiday away from work) one chem that
liquefies only certain plastics is trichloroethylene...acetone is another and some I can't
recall the names of...but they all STINK

And they are really dangerous.....you need a small room set up to use these
safely, constant evacuation of air, wear a positive air pressure hood...that sort of hassle.

We have some of the 2.5v 100 farad caps at work, I will find out where they come from and how much $.
But a google search turns up suppliers and also plans for making LED flashlights using them.
www.google.com/search?hl=en&q="100+farad"+capacitor+2.5&btnG=Search&aq=f&oq=&aqi=
www.los-gatos.ca.us/davidbu/solar/pond_lights.html

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Some mornings I wake up cranky.....but usually I just let him sleep in -

Agent420

This is a pretty clever idea... my wife has used that clear setting material for a couple of craft projects and they came out great.

Coincidentally, I recently came across Peter Todd's artwork page where he has somewhat of a similar project - a battery powered watch running inside the clear block.




▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔

CounterRotatingProps

Great!

How long before we will see the " Minkowsky Clear Thinking Cube " ? [noparse]:)[/noparse])

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔

HollyMinkowski

" Minkowsky Clear Thinking Cube "

Not bad

Got to head back to work Mon so I will have limited time for this artsy-crafty project.
But it is a fun idea, and I just have to get it made. Once I figure out the wireless power
part the rest won't be so bad. I think I can top that watch in a block art piece. I'd like a
super tiny screen from a defunct cell phone inside, or 2 or 3...imagine the possibilities

And of course lots of blinking LEDs
And I have a small bunch of scrolling led text displays that were given out at a seminar.
Green, blue and red ones.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Some mornings I wake up cranky.....but usually I just let him sleep in -

HollyMinkowski

WoW...just look at this guys project.
Now that is different.
Looks really easy to do.
I could just get a base and start building a strange circuit.
Just flatten out the pins on a dip prop like a sm chip and
solder directly to them.

This is lots easier than encapsulating in plastic and every bit as cool.
Only problem is it will get dusty and soon look like cobwebs are
hanging all over it.

All I need is solder, wire, colorful parts, LEDs blinking, little cell type video screens and a wooden base.
And stick a tiny motor and propeller on top?


This is too good an idea to pass on...got to see about getting a finished wooden base.
I think they sell them in the craft dept at Wal Mart and Hobby Lobby.

I could stand the prop on end in the middle of the wire maze and attach
pieces of colorful wire to certain pins to look like arms and legs, then stick a
tiny doll head on top and put an LED inside to make it glow. I have some old Barbies,
is the prop male or female????????



▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
- Some mornings I wake up cranky.....but usually I just let him sleep -

CounterRotatingProps

> is the prop male or female????????

Oh gosh, Holly,

I bet more than a few of the guys here *almost* typed in a snappy reply (about 'polarity' or 'pin outs' [noparse]:)[/noparse] and then quickly decided against it. *cough* (I on the other hand have blundered right to it, haven't I ? [noparse]:)[/noparse])

Yikes - if you use one of those old heads as in that picture, the question would have to be " male, female, or alien " ... Ken and Barbie with Props in their bellies - now there's a pending classic.

Well, "She's a good ship" is an old custom. But maybe we have to let the Dad of the Prop (Chip) tell us whether it's a boy or girl ... and the happy Parallax family will soon have another, eh?

cheers
- Howard

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔

AJM

Here is a short clip that recently caught my attention on the subject.

www.ted.com/talks/eric_giler_demos_wireless_electricity.html

Not to get off topic too much but I didn't think this was new technology, just dormant?