Boltu

Boltu is the workbench companion for anyone who builds and experiments with Leyden jars, the 18th-century glass capacitors that launched the science of electricity. Whether you are a science educator planning a classroom demonstration, a museum demonstrator, or a hobbyist who loves the crackle of a well-charged jar, Boltu gives you the physics, the tools, and the safety knowledge you need at your fingertips. At the heart of Boltu is a precision physics engine that calculates capacitance, safe working voltage, stored charge, and energy for any jar you describe. Tell it the glass type, vessel geometry, foil dimensions, and room humidity, and it instantly shows you how many millijoules your jar can safely store, how long it will take to charge from your chosen source, how long a spark gap it can jump, and which of five sensation bands the discharge falls into, from a harmless tick to a hazard-level jolt. A binding-limit indicator always tells you whether your ceiling is set by the power source, the glass wall, or the rim flashover voltage, so you know exactly where to improve your design. The Jar Builder walks you through every parameter with a curated catalogue of eight vessel types, eight glass materials, and three foil options drawn from real workshop practice. The Photo Gauge uses your camera to measure a real jar directly from a photograph: drag four pairs of pins over a ruler reference and the app computes inner diameter, foil height, and rim margin to the nearest tenth of a millimetre. The Charge Sheet generates a full technical report with a charging curve, a stage table at 25, 50, 75, and 100 percent of safe voltage, a spark-gap ruler, and a battery configurator for wiring multiple jars in series or parallel. The Sources tab catalogues eight historical charging methods, from a glass rod and silk to a Wimshurst disc machine and a Van de Graaff belt generator, each with effort ratings, output figures, and mechanism descriptions. The Demos tab covers nine classic electrostatics demonstrations, each with feasibility checking against your current jar so you always know which experiments are within reach. Save multiple jar builds to the Cabinet and switch between them instantly. Boltu is built for the bench, the classroom, and the curiosity cabinet alike.