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:

• hand saw,
• silicone rubber sealant (small tube costs $5, using less than 10%),
• 6" polyethylene 1/8" ID tubing ($0.10),
• 12 gauge solid copper wire ($0.12)
• Torch igniter, Ann Arbor Welding Supply, LIG08100, $15.14 + tax

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:

• 1 - grounding the probe tip,
• 2 - squeezing/compressing the crystal/handle,
• 3 - while maintaining compression, remove grounding from probe tip,
• 4 - SLOWLY release crystal/handle while touching probe tip to object to be charged,
• 5 - when correct charge is achieved, pull away probe tip -- while maintaining constant/unvarying compression.
• Object is now charged with decompression charge.