Low-Power Wireless Charging

Step 2 Needed Parts and Equipment

I hate to let a lot of people down, but an oscilloscope is absolutely needed here. Without it you won't be able to tune your horrible handmade inductor and the circuits won't match. These things are really finicky, even if you went with the relatively large bandwidth that my values provided.

If you have access to one, then great! That, a soldering iron, some wire cutters, and pliers are all the tools you need.

As for materials, you will need a few different parts, but nothing too fancy.
Master coil/oscillator:
24AWG enameled magnet wire
Prototyping board
2 150nF capacitors
2 10K Ohm resistors
1 100Ohm resistor
1 100nF capacitor
A bunch of 2N2222 transistors (I used 3, you can use more or less depending on availability)
5V regulator and DC jack to plug it into the oscillator

Slave coil/CW generator:
More wire
Another prototyping board
2 150nF caps
4 2.2uF caps
4 low forward-voltage drop schottky diodes (search digikey for ones with Vf<400mV@1A and Ir<1mA@20V)

Note that technically any schottky diode will work here, so if you want to just build it without much efficiency then feel free to use whatever you wish / can get your hands on.

Comments

[rhombus2210]

Any suggestions on what kind of DC jack to use?

[gripen40k]

Nope, it can be anything. I used a barrel jack because that was the cheapest one at my electronics store.

[rhombus2210]

Thanks! I appreciate that you still take the time to answer questions.

[.Unknown.]

So...an oscilloscope is ABSOLUTELY needed? Would I be able to make do with an inductance meter and experimentation? How did Nikola Tesla do this?

[gripen40k]

Ah, well if you happen to have an inductance meter then you can get two matched coils fairly easily. The oscillator won't be perfect but it'll be close enough to work. Nikola Tesla probably used large formers for his coils, as seen in the tesla coil. Using a large former one could make a coil with the exact diameter and length so it's inductance would be very close to the desired one. He could have also made some sort of inductance meter or maybe used sound circuits to match the tone between the two. Who knows, he did it somehow :) Of course if you have a lot of time you could do this with experimentation alone, however an oscilloscope is by far the easiest way!