Historic Transistor Photo Gallery

Photo Essay – Shockley 4 Layer Diodes




Samples of 1950s Shockley Diodes from the Palo Alto Shockley Plant


Photo Essay Commentary

These Shockley diodes have been recently donated to the Transistor Museum by Ludwell Sibley.  Here are some related comments by Mr. Sibley: “These are literally floor sweepings. They were gathered by a high-school buddy who had a part-time job as night janitor in the Shockley plant in Palo Alto.  I believe it was the main facility on Page Mill Road; I think there was another building some distance away. These (diodes), on being tested, turned out to be almost all rejects.  A bad PNPN acts as a mediocre zener diode.  A few diodes turned out to work.”


The two leftmost diodes are labeled – the metal unit is a 4N120D and the glass unit is a 4E20D.  Shockley also made a stud mounted diode, but none were included in this lot.  The 4G200D shown earlier in this PhotoEssay is an example of a stud mounted device. 


Go To PhotoGallery Shockley Diodes Page 7







Copyright © 2005 by Jack Ward. All Rights Reserved.