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Tesla Coil - For Research and Education - $220
condition:
excellent
make / manufacturer:
Scientific Glass Apparatus Corp
size / dimensions:
14" x 2"
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This Tesla Coil is of a standard popular design. The brown Bakelite body is around 10.5" long and the (silver colored) electrode tip is another 2.5". The main body is around 2" in diameter and can be easily held and manipulated with one hand (e.g., to search around for leaks). The power cord is around 7.5 feet long and is in very good condition with no worn or frayed spots. The cord is very flexible.
There is a voltage adjusting knurled knob in the bottom. This model has no separate ON-OFF switch; fully CW is 0 volts or off. You can plug it into a switched outlet or power strip or add an in-line on-off rocker switch for convenience.
Tesla Coils such as these are frequently used in the laboratory to check glass vacuum lines for leaks (and that was the main use of this item for many years). See: Coyne, G. S., & Cobb, C. L. (1991). Efficient, inexpensive, and useful techniques for low vacuum leak detection with a Telsa coil. Journal of Chemical Education, 68(6), 526. doi:10.1021/ed068p526 (This paper reports the colors made by different vapors leaked into the vacuum line. Air = purple; CO2 = greenish white; Acetone = turquoise; etc..)
For another discussion, see Physics Forum: "Vacuum Leak Detectors. High-frequency induction, Tesla-type coil, with one end of secondary attached to a metal electrode. Point of leakage is indicated by a bright spot where discharge enters evacuated glass assembly. Can be used for exciting Geissler tubes, but intended for ***intermittent use only,*** for periods of up to 4 minutes, followed by at least 5 minutes “off” between periods of use. Output is 10,000-50,000 Volts at a frequency of three to four megahertz."
Reference: https://www.physicsforums.com/threads/tesla-coils-detecting-vacuum-leaks-why.713905/
This coil can also be used to activate gas discharge tubes (Geissler Tubes) and ignite high pressure sodium or mercury arc lamps. It will also create a glow in a regular fluorescent tube but I don't have one to photograph as a demo. The "lightning" photos shown in this listing were made using this Tesla Coil and made in Feb 2025 using a cell phone camera.
This Tesla Coil has some cosmetic problems from years of use in research and education. It is in excellent working condition. It operates on 115 VAC. It does not need a separate power supply or transformer. This model works as is by plugging it into a 115 VAC outlet.
SGA was founded in 1918 by William O. Geyer, Sr.. Geyer was inducted into the New Jersey Inventors Hall of Fame for some of his inventions. Over the years, SGA grew and expanded to over 300 employees in 8 offices. It survived into the 1980s and was then either acquired, merged, shuttered, or otherwise disappeared from active business records. I'm unable to trace it further.