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This non-functional wireless power circuit makes transistor almost hot

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So is my only solution here then to wind up enameled wire over a toilet paper roll? or can I get away with using a transformer? I don't mind if the receiving circuit can run at max power if it is hung onto the transformer/inductor via the insulated wire that makes up part of the receiving coil.
 
I have never seen a wireless charger where the transmitting coil must radiate a magnetic field and the receiving coil must detect the radiated field. Most inductors and transformers do not transmit or receive an external magnetic field.

I think the coils must have an air core for high VHF frequencies, a ferrite core for low VHF and an iron core for audio frequencies. The transmit and receive cores must efficiently couple together.

You were confusing the impedance of a 600 ohm transformer with the 10 to 20 ohms resistance of its wire.
 
Oh. so that 600 then I guess is the number of turns to make up the low resistance. So I can get away with winding enameled wire around a toilet paper roll? I'm just trying to make it so that the wire I put into the circuit is as bad as the first inductor I used which someone claimed smelled when my first circuit wasn't working.
 
The whole point of wireless power transfer is to transmit power from a transmitter part to a receiver part without having fixed wiring between the two. If you use a conventional transformer, both parts are permanently attached by wires, because both coils are wound on the same core.
 
Just follow the directions in the link you posted. Take the time and wind your own transmitter/receiver coils. That's really the best (if not only) way you'll get the results you're looking for.
 
Just follow the directions in the link you posted. Take the time and wind your own transmitter/receiver coils. That's really the best (if not only) way you'll get the results you're looking for.

I suspect that won't give him the "results he's looking for", but it will allow him to light some LED's wirelessly as per the link. I get the impression he's expecting to transfer a lot of power wirelessly to charge a phone (or two).

But at least if he follows the instructions it will demonstrate what can be done.
 
Wireless power transfer is, by its nature, very inefficient. You can't expect long power transmission distances (I wouldn't expect you'd be able charge anything from more than 6 inches away with any sort of efficiency), regardless of what you pump into it.
 
realcircuit.jpg

Ok so now I tried the manual route. I took a mini radio shack circuit board cut the corners around it to make hooks and wrapped 28awg magnet wire around it 30x and that took some time to do. For extra protection, I added 2 10-ohm resistors in parallel and I added a 1uH and a 100uH inductor in series with the coil. The ohmmeter measured the whole resistance of that part to be 10 ohms. I replaced the tip41 with a tip31 because of the ridiculous local pricing of tip41 and tip31 can handle 3A.

So I tried the circuit again and the LED lights dimly when I have the receiving mini coil touch the big transmitting coil, but also, the resistors and inductors on the radio shack circuit board were getting very hot slowly while the circuit was on and the tip31 transistor was warm but not as hot.

I'm afraid if i remove the resistors, I'll blow up the transistor. Is there another solution other than to constantly wind coils of several dozen turns?
 
The current is high because the inductance is too low for the low frequency. The coil is acting almost like a piece of wire. Increase the inductance by adding an iron or ferrite core to the coil then it will have less current, have more power transmitted and have more power received.
EDIT: like this:
 

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The current is high because the inductance is too low for the low frequency.
Could I also get better results if I raise the frequency (from 30khz to like 200+khz)? or will that create other problems?

The coil is acting almost like a piece of wire.
This is why I was afraid to make the connection without the resistors in place.

Increase the inductance by adding an iron or ferrite core to the coil then it will have less current, have more power transmitted and have more power received.
Was the only reason why you suggested several posts ago that I should use ferrite core instead of air core, because its a way to increase inductance?
 
You are making a transformer, half transmits and the other half receives.
Have you ever seen a transformer with no core, just an air core? Sure, a VHF or UHF radio frequency transformer.
An iron or ferrite core in your coils will make them more efficient without changing all the parts to operate at a high radio frequency.
 
So now I'm better off just buying transformers then because the way I'm doing it now will take longer.

No, because a transformer isn't wireless - so it makes your entire circuit pointless.

You seem to be just 'stumbling about', with no idea whatsoever of what you're trying to do, or how to do it.

Here's a page for a wireless power module, which also includes a fair amount of info about itself. It might be an idea if you bought one!!.

https://www.banggood.com/Wireless-Power-Supply-Coil-Module-Wireless-Charger-Module-p-907971.html
 
Transformer, The flux or energy mostly stays inside the transformer. It is not allowed to go through the air. You will not be transmitting. Every time you say transformer some one says NO.
upload_2017-9-27_6-43-4.png

Coil: Some of the energy will make it to the other coil. Here is a "rod" coil. An air coil also works.
upload_2017-9-27_6-48-58.gif


Some time back you said Toroid. Red I is current. Blue B is flux. It stays inside the coil. Will not travel through the air to another coil.
upload_2017-9-27_6-53-47.gif
 
Loop inductors are great for coupling power. The coils below are easy to make and work well. The other inductors you mentioned are specifically designed to not radiate nor be particularly sensitive to external magentic fields.

**broken link removed**


Here is a Google seaerch:
https://bfy.tw/E9xh
 
Notice the vast distance between the coils on the cheap Chinese charger product: a few millimeters which is a piece of paper or a thin plastic housing. With an input of 12V at 300mA (3.6W) then the output across a 3mm gap is 5V at 360mA (1.8W) then the efficiency is only 0.5 times. The coils are tuned with capacitors to resonate at the frequency that is used.
 
I guess I'm sortof close with the transformer idea, except if I sliced it down the right way, I'd get the pieces necessary for wireless transfer. Dick Cappels, that image link you wanted to show me is sadly broken. and Ron Simpson, I noticed in your answer, you marked N and S on your coils. Would I get better power transfer results if I used a magnet with north and south poles on them instead of a ferrite rod that audioguru suggests? or would that not matter much?
 
It clearly tells you how to make the coils. They are not inductors. They are RADIATING COILS. I wind coils all day long for my metal detectors and it would only take me about a week to wind 30 turns around a 5cm diameter item from the kitchen. The thickness of the wire is not important. It is effectively and actually an ANTENNA. And after winding them I would rest for 10 days to recoup from the exertion.
 
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