In Karen’s most recent episode of The Learning Circuit, she shows off some of the most amazing types of transformers, the Tesla coil. Tesla coils are a type of step-up transformer that incorporates a special type, called a resonant transformer. These function at a high voltage and high frequency. That high frequency can be modulated to even play music. The visible sparks generated actually excite the air surrounding the coil, and make sound. Watch as Karen shows off 5 kits and see how incredible these transformers are.