Warren Smith, Mark Kennedy, Angela Plagemann
2477 Randall Lab, 500 E. University University of Michigan Ann Arbor, MI 48109-1120
Phone: (734) 936-2498 Fax: (734) 763-9694
Email: demolab@umich.edu

Low Cost Competition

Apparatus Title: Piezo-Charger

Abstract: A modified commercial gas torch ignition is used to produce both positive and negative high voltages (~10 kV) suitable for many electrostatics demonstrations. A hand-compressed piezoelectric crystal generates necessary voltage for many electroscopes and can replace rods and fur or silk, electrophorus, and in some cases a Van de Graaff or Wimshurst machine.

Equipment required to construct apparatus:

Total Cost: $20.36

Sketch of the Apparatus:

Description: This apparatus utilizes a commercially available Acetylene gas torch igniter. The unit is a steel hand-held squeeze compression device wherein the force of a hand squeeze is translated into a highly magnified compression onto the piezoelectric crystal. The crystal then translates compression to charge. The charge, which is smoothly and infinitely variable, is imparted to the probe tip in opposite polarity to the handle/grip. Both polarities are available at the probe tip and may service both positive and negative high voltage static needs. The commercial unit is modified so that it no longer sparks but instead provides an insulated pathway for the charge to operate various demos. Typically, we use this device in conjunction with a grounding platform, so that the piezo-charger and instruments may be referenced to ground potential.

Piezo-charger tip polarity is changed by:

Construction: The 12-gauge wire is soldered to the tip of the igniter. The tubing is slipped over the wire. The end of the wire is curled and filled with solder to form a tip. The junction of the igniter and the tubing is filled with sealant to maintain rigidity.