High Voltage and Franklin's Bells at Low Cost
High voltage supplies are often used in physics classes for demonstrations and laboratory work. These devices deliver several thousand volts DC, while limiting the current to a safe level, typically under 5 mA. One issue with these power supplies is their expense, which means schools may not have one. Less expensive homemade units have been discussed before, but here we present an inexpensive, off the shelf substitute, namely electric bug zappers, which can do nearly the same thing as the more expensive supplies, and we connect it to an easy to build Franklin's bells setup that is suitable for measuring the current shuttling across it.
The Physics Teacher