Wireless Power with a DIY Tesla Coil

If you have a newer-model smartphone it probably comes with built-in wireless charging. There's even talk of wireless charging coming to electric vehicles in the future. Image someday having a home with no plugs or wires, where everything just works. It’s not magic, it’s no mystery, it’s science!

Nikola Tesla is typically credited with inventing wireless power transmission, though some theories have suggested the technology existed as far back as ancient Egypt. Either way we can honor the great inventor's namesake by putting together a DIY Tesla Coil at home. This coil will be powerful enough to wirelessly light a lightbulb and even create mini lightening bolts that spark from the surface.

CAUTION: Do not use this project near persons with pacemakers, sensitive electronics or flammable materials.

How it works

All it takes to transmit electricity wirelessly is a system that converts a low voltage to a high voltage and simultaneously turns itself on and off very quickly. That's what we're building.

A few volts of electricity are passed to one side of a coil of wire and to a grounded capacitor connected to the negative side of the power supply. The other side of the coil is connected to the collector of a transistor. When connected to a power source, the capacitor begins to charge while the coil begins to radiate an electromagnetic field. This coil is then placed around a second coil with many more windings of a smaller gauge wire which creates a transformer, converting a low input voltage to a very high voltage in the second coil. This secondary coil is then connected to both a resistor connected to the power source and the base of the transistor, which then shuts off the flow of current to the first primary coil.

This circuit configuration creates a feedback loop that automatically turns on and off hundreds of times per second, creating a high voltage, high frequency electric field capable of transmitting wireless electricity.

Here are the parts you’ll need:

For those who don't want to source the individual parts, Drew Paul has made a kit of all the components available as well. 

Also, get the circuit diagram here.

Winding the Coils

To begin, we’ll need to wind the coils. To do this, you'll need to be precise and accurate otherwise the coils won’t function properly.

1.) First, we will make our primary coil. We will wrap our short 2.5-inch PVC pipe with the 16 gauge insulated copper wire making three rotations evenly spaced about 1/4-inch apart. Secure the wire with tape, then strip the ends.

2.) Next, we will take our 2-inch PVC and line up the magnet wire across about 1/4″ from the bottom and secure it with tape, leaving several inches extra on the end.

3.) The next part is tedious, so get comfortable. We will now wrap the magnet wire around several hundred times until we reach around 1/4″ from the top. Be sure to wrap tightly, straight, and without gaps between windings. Also, be sure to add a piece of tape every inch or so to keep everything secure.

4.) Once you reach the top, leave a couple of inches of additional wire, cut and strip both ends by lightly sanding the ends of the wire. Then you can secure your winding by wrapping with tape from top to bottom.

5.) Lastly, press the stripped wire end between the top of the PVC and your 3-inch washer and secure with glue. This will act as your secondary coil and transmitter cap.

Build the Circuit

1.) First, install the three legs of the Transistor in breadboard slots E1, E2 and E3 with the heat sink and front of the transistor facing back toward slot F.

2.) Next, insert the three capacitors into slots H14/H17, I14/I17 and J14/J17 respectively so that they are in parallel.

3.) Now, connect the first leg of the transistor to one side of our capacitors with a jumper wire. Connect one end of a jumper wire to slot D1 and the other to F14.

4.) Next, we’ll connect a jumper wire from the other side of our capacitors back to where our ground will be. Connect one end of a jumper wire to slot F17 and the other end to slot D5.

5.) Insert one end of your resister on the same column, slot C5, and the connect the other end of the resistor to the base of the transistor by inserting it in slot C3.

6.) Next, connect one last jumper wire to slot A5 and the other end to slot B11. This will allow us to connect to our primary coil.

7.) You can now insert the secondary coil into the primary coil keeping, it centered. The bottom wire of your primary coil can be inserted into slot A11. The top wire from your primary can be connected to slot A2. Connect your secondary coil by inserting the bottom wire into slot A3, and the base of your transistor. Check all connections before proceeding.

8.) Lastly, connect the positive from your power supply (+) to slot B5, and connect the negative from your power supply (-) to slot B1.

9.) You may now carefully test your circuit by plugging it in momentarily.

NOTE: To avoid overheating, only power your Tesla Coil for short durations of no more than 20 seconds or less.

Construct the Enclosure

Now we will build an enclosure to display our Tesla Coil. This enclosure is also important in order to isolate the coil from flammable materials and sensitive electronics as well as to keep the coil upright and to provide a platform for experimentation.

1.) First, place a washer, nut, and end cap on each of the threaded rods. Then you can drill a 5/16″ hole in each corner of the plexiglass sheets.

2.) Insert the four rods into the holes in one of the plexiglass sheets and add a washer and nut to secure, creating the base of the enclosure.

3.) Place your circuit and coil on top of the sheet, making sure it is centered, and remove the adhesive backing from the breadboard in order to affix it to the platform.

4.) Add a nut and washer to each of the rods, place the second plexiglass sheet on top and adjust in order to tightly hold the coil in place. Once secure, add an additional washer and nut to each rod, tighten, and add an end cap to each.

5.) Your enclosure is now complete and your Tesla Coil is now ready to use!

Try it Out!
Now that your Tesla Coil is complete you can begin your experimentation.

You can now connect the power and watch as florescent bulbs light up like magic once placed near the coil. Watch as sparks fly when metallic objects are place near the coil (take caution!) or use a digital multi-meter to observe the high voltage field at varied distances from your coil.You can even tune your coil by lifting or lowering the primary coil to see the effects of different positioning.

Want to take it a step further? Add a resistor to an LED to to create your own wirelessly powered light bulb. You can even experiment with wireless charging coils to create your own wireless charger for mobile devices. The possibilities are endless!

What real world applications does this technology have? How can this technology be used in the future? What will you do with your Easy Tesla Coil?

Give this project a try and let us know how yours comes out!

[All images courtesy Drew Paul / Drew Paul Designs]