Literally, Jumping the Spark!
This photo shows an electrostatic charge generator. It was designed by Kevin Dunn, Ph.D. and constructed from a kit supplied by cavemanchemistry.com. It is based on the original Dirod apparatus conceptualized and designed by A.E. Moore. The ball gap and capacitors were added later following Dr. Dunn’s instructions, from materials purchased at Home Depot.
Despite being hand-cranked, this apparatus generates a strong 1″ spark across the ball gap with potentials of up to 120 kV (kilovolts)! The amperage is miniscule, so the electrical shock is not life threatening. But you will definitely know when you get too close to one of the electrodes–there’s quite a lot shock value here! While winding up the machine, the odor of ozone can be detected.
Electrostatic charge generators are among the oldest electrical machines devised. Benjamin Franklin and his contemporaries experimented with several different designs, the Wimshurst machine configuration being the most popular in years since. Operated in reverse, the device becomes an electrostatic motor.
The manual action of winding up the electrostatic potential is reminiscent of operation a Jack-in-the-Box children’s toy… you never quite know just when the spark will jump, so it is a surprise and a delight!