How to Build a High-Voltage Power Supply for Plasma Physics and More
The Plasma Channel has a guide to creating a small high-voltage power supply using a repurposed flyback transformer from a tube TV.
In case you’re not an electrical engineer, let’s go over a quick refresher of how electricity works. Ohm’s law states that I = V/R, meaning electric current (measured in amperes) is equal to the voltage divided by the resistance of the circuit. As the formula shows, voltage, resistance, and current are all inextricably linked. Does that mean a high-voltage power supply needs to draw a huge current? No! A single amp of current can result in 10,000 volts, as long as the resistance is 10k ohm. To put that concept into practice, The Plasma Channel on YouTube has a guide on how to build a small high-voltage power supply for plasma physics and more.
The best analogy for Ohm’s law comes from hydraulics. Imagine water flowing through a pipe. In that analogy, the flow rate (as in liters per second) is equivalent to the current. The pipe itself is similar to a resistor in a circuit — a higher resistance is like a smaller pipe. The voltage is akin to the water pressure. So, given a constant flow rate, making the pipe smaller increase the pressure — just like increasing the resistance increases the voltage. In practice, however, you still need to overcome the resistance. A piece of rubber, for instance, has effectively infinite resistance. Putting rubber in a circuit doesn’t result in infinite voltage, it stops electrical flow altogether like a plug in the water pipe.
Air has very high electrical resistance, and creating a plasma arc requires quite a lot of voltage. A power supply like the one described in this video is capable of producing something like 15,000 to 20,000 volts—but can do so with the current typically available on residential mains power. The key component of this build is a flyback transformer, which can be scavenged from an old tube TV. The cathode-ray tubes in those old TVs also required a high voltage, and so their transformers are perfect for the job. The video explains how to repurpose the flyback transformer for use in plasma physics experiments, and it only requires a transistor and a couple of resistors. You can also use it for other cool physics demonstrations, such as ionic lifting — just be careful, as flyback transformers and mains power are potentially dangerous.