15. Pancake coils

<Intro>

After doing the tesla coil project from 2015-2016, I wanted to try another method of transmitting electricity wirelessly, and in this case, using pancake coils as a way instead of using Tesla coils (so instead of Nikola Tesla's way, it's Michael Faraday's way). With the pancake coils, while it was a rather short distance just to transmit energy, it does allow more current to be transmitted, meaning you can power devices that use more current such as a phone, and there are even other devices that use wireless charging using that same principle.

<Side view>

<Operation>

The way it works is that you have the transmitting coil and the receiving coil. The transmitting coil has electricity flowing through the 2 coils, both of which when energized, generate a magnetic field due to the inductive nature of the coils. As soon as another coil is close to the transmitting coil, the magnetic field gets transferred to that coil, which is then energized to convert those magnetic fields back to electricity, almost similar to that of an air-core transformer. The receiving part has a simple rectifier, which converts the AC current back into a DC current.

For that, this method allowed the magnetic fields to be concentrated between the 2 coils so that the power won't be lost during the process. It can be improved using a ferrite plate on each coil so that the magnetic flux can be concentrated even more. For this current design, it uses a power transistor (NTE130, or 2n3055), and a 705-ohm resistor.

<Bottom view>

<Tidbits>

This circuit uses 12 volts, which also means adding a powerful fan to cool down the power transistor. Without the fan, the transistor will get very hot, conducting heat through the aluminum base, up to the point where the unit is too hot to handle, or the risk of damaging the transistor. In addition, due to the inefficiency of wireless power transfer, the voltage/current might be low from a certain distance.\Still, it was a fun experience, and as a result. I have two types of projects that feature two ways to transmit electricity through thin air!

 Wireless test 2

<Circuit>