Historic Transistor Photo Gallery

Photo Essay – Bell Labs Bead Type Point Contact



  Case Styles of Early Bell Lab Transistors  

Photo Essay Commentary

The above photo shows the case styles of several early developmental triodes from Bell Labs – these are all from the early 1950s. The four devices on the left are all plastic capsulated, while the device on the right is a metal cartridge.  The two bead type transistors are shown at the far left, with an early prototype followed by a more mature 1689 style.  Plastic capsulation was abandoned in the mid 1950s, largely due to the fact that the plastic technology of the time did not completely protect the transistor junctions from moisture-based degradation [2]. 



The drawing on the left [4] is a detailed view of the components of the hermetically sealed metal-cased version of the Western Electric point contact transistor style that evolved from the earlier cartridge and beads types shown above.  The 2N67 and the 2N110 are examples of point contact transistors of the style shown in the drawing. 










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