About Copper Oxide rectifiers

Didn't know this. Sounds better than the selenium type. I know they were used in older meter movements.

Copper Oxide Rectifier

With the use of the copper oxide rectifier in a recent receiver of the portable type, their popularity will possibly be revived for radio purposes, as in the days when they supplied rectified a-c for the fields of loudspeakers.

Any device which offers a high resistance to the flow of current though it in one direction, and a comparatively low resistance to the flow of current to it in the opposite direction, makes a good rectifier for an alternating voltage. This is the case of the dry contact rectifiers, such as the copper oxide type. 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.

The copper oxide rectifier can be connected in either the half-wave rectifier or full-wave rectifier circuit.

The test for proper single disk operation is to impress a ½ -volt d-c across the disk in the conducting direction; then the current should read should read 0.5 amperes or more. By reversing the battery polarity a current of no more than 2 ½ Milliamperes should flow when 2 volts is applied to the disk in the non-conducting direction.

This was copied from the General Electric Company Electronics Department, booklet #175-3012A THE ABCs of RADIO (copyright-1943)

Wow interesting ,all that reading made my head hurt No really very interesting i book mark lots of post this will be one.
Thanks.

Very very intersting.

Actually, they are about as bad as selenium, and, get eaky, and, weak.
Bill Cahill

By today's standards, copper oxide rectifiers are virtually useless for most power-handling applications. Mostly, their reverse voltage is low, requiring 'stacking' for use in all but small-signal circuits. HOWEVER, they have very nice forward-conduction charactertistics that make them ideal for certain "variolosser" applications, and as such they were used by Western Electric for many Bell System compander circuits. What's more, they can be fabricated on the kitchen table without too much trouble or mess. Some crystal radio experimenters report better-than-germanium results as detectors, too!