Inductive Charging

[AtomSoft]

Ok i have to do a project for someone and they asked me as a side question if i can do inductive charging. I told them "At this current time it is not possible"

I would love to be able to offer that service. I read a ton on this and it doesnt help much... Im more of a need to be sure and ask my questions kind of person...

So here is the main thing...

Is it safe to assume that inductive charging is just the same as cutting the transformer into 2 parts .... So basically all i have to do is place everything from the second half of a transformer and the ac to dc and regulator in the actual device?

What this means is... ??? (is this correct)
1) Transmitter sends AC
2) Receiver must:
a) Using second coil (step down AC)
b) Use a bridge rectifier to convert to DC
c) use a regulator to power the other circuitry (including the battery charger portion)

If this is the just of it then... ill give it a shot if not and its more complicated than i think just help me out a little and ill try to pick it up and test

 

[JimB]

What this means is... ??? (is this correct)
1) Transmitter sends AC
2) Receiver must:
a) Using second coil (step down AC)
b) Use a bridge rectifier to convert to DC
c) use a regulator to power the other circuitry (including the battery charger portion)

Yes, that is about it.

What you have to be aware of is that when you have a transformer which has the core cur into two parts and you separate those parts, the inductance of the primary winding will drop considerably.
What this means is that the current in the primary winding will rise considerably as the two halves of the transformer are pulled apart. If it is a power transformer, the magnetic force holding the two halves of the transformer together will be considerable.

You may want to do a few experiments before committing to build this for someone, if large currents are involved think even more carefully.
The "cut transformer" will not be as efficient as complete one, there will be a lot of magnetic flux leakage.
Also, consider using a higher frequency and a ferrite pot core for the transformer.

JimB

 

[AtomSoft]

OK thanks, will do. Ill be sure to play a ton before even saying i know it some

 

[ronv]

Are you seeking something like a cell phone charger?
If so they often use resonant circuits running at a high frequency. I have a schematic somewhere if that is what you are looking for.

 

[AtomSoft]

Something like that would be great thanks

 

[ronsimpson]

Here is more to read.

 

[AtomSoft]

Thnx will read asap ... So sleepy... Thanks again!

 

[AtomSoft]

CoOl, receiver seems easier than transmitter but toyally doable

 

[i_build_stuff]

I was about to say the same thing as ronv... a resonant air core transformer.

It's exactly the same idea as a Tesla coil, just without the high step up.

 

[ronv]

This is the one I was looking at.

**broken link removed**

 

[JimB]

Ronsimpson:

That is several orders of magnitude more complicated than what I had in mind, but depending on the power transfer requirements probably a better off the shelf solution.

JimB

 

[AtomSoft]

From what i can see its super simple!

You dont need most of that stuff... omit anything with the Enerchip and crap...

If im right then this should be it:

 

[ParkingLotLust]

That looks pretty simple! Might have to build one of these myself..

 

[AtomSoft]

Yeah, im planning to try it soon

 

[AtomSoft]

Ok simple question... i dont have 4069 IC on hand.. its a hex inverter (6 bit)... but i do have a SN74H05N which is the same thing technically... is it ok to use the 74H05 instead?

 

[ParkingLotLust]

Should be fine. Try it and see!

 

[gerty]

Check out a cordless toothbrush, that's how they charge.

 

[AtomSoft]

I know but no funding on this and im not spending my own cash But i think i should and perhaps just take the internals out and use that (thinking lazy)

 

[ronsimpson]

My toothbrush charges at 60hz. Very simple. Many turns of wire.
I noticed one of the examples runs at 13.56mhz. 4 or 5 turns of wire.
I think the FCC has frequencies set aside for this. I have not looked. I think there is one at about 100khz, 455khz. (Remembering projects decades ago.) There must be one at 13.56mhz. You probably should look at what frequency!

 

[AtomSoft]

Ill check around... thanks... i guess being in the USA i should follow FCC regulations/rules... kind of temped not to

Quick google: https://apps.fcc.gov/eas/comments/GetPublishedDocument.html?id=25&tn=696606