[Milsurplus] Copper Oxide rectifiers

[John Hensley]

Copper Oxide rectifiers were used by many companies for a time.  Western Electric made teletype loop supplies using them and Lionel made their train operating transformers using them.  Here is some information that I have collected:
This is a robust rectifier design offering full recovery when allowed to cool after overload.  From the General Electric Company Electronics Department, booklet #175-3012A THE ABCs of RADIO (copyright-1943):

"The copper oxide rectifier is made in the form of a copper disk, coated on one side by a layer of copper oxide. The copper oxide is plated with nickel to allow good external circuit contact. The juncture of the oxide and copper offers a low resistance to the flow of current from the oxide to the copper, but a high resistance to the flow of current in the reverse direction. The detailed operation of this device is complex, but in general it involves the formation of thin films at the junction of the oxide and copper in which the molecules are so polarized that the transfer of electrons in one direction requires much less work than a similar transfer in the opposite direction.
Copper oxide rectifiers possess a definite breakdown voltage and breakdown temperature. If either critical value is exceeded, the rectifier will pass current freely in both directions. After the unit is cooled or the high voltage removed, it will immediately function again as though it had not been overloaded."  <--> Hope this gets you started,
John W5JV