TRANSISTOR MUSEUM™ Historic Transistor Photo Gallery
Transistor Size (1/4” Diameter X 1/4”H) Standard T0-5 Case Packaging - None	GE GLASS TRANSISTOR PROTOTYPE TYPE Germanium NPN Rate Grown Junction Transistor USAGE Experimental Packaging DATE INTRODUCED Mid 1950s CASE STYLES Transparent Glass AVAILABILITY Very Rare (Prototype)
HISTORIC NOTES The first junction transistors from the early 1950s were primarily encapsulated in epoxy-type plastics, but this proved unreliable due to moisture penetration through the epoxy. General Electric was an early leader in metal-cased transistors, and developed a reputation for high quality, rugged devices (see the 2N170 and the 2N107.) However, metal cases were relatively expensive, so there was experimentation with less expensive glass packaging. According to Carl David Todd, GE developed a glass-cased transistor prototype production line in the mid 1950s to evaluate the suitability of this approach for commercial devices. Shown above are samples from this GE prototype work. These transparent glass cases have remained intact for the past 50 years, and the transistors are still functional. The white powder is a substance called molecular sieve, and was used to absorb moisture in lieu of the vacuum exhaust used in the old derby tophat form of GE metal can with the exhaust tube at the top. Although thousands of these prototypes were developed (both NPN rate grown and PNP alloy junction), GE did not pursue this line in larger quantities, and never commercialized the glass case style - only a few specimens exist today.
Copyright © 2005 by Jack Ward. All Rights Reserved. http://www.transistormuseum.com