Copper-Oxide Rectifier Used for Radio Detection and Automatic Volume Control

A new type of radio detector has been developed which depends for its action on the rectifying properties of the boundary between copper and cuprous oxide formed on the copper at a high temperature. In order to make the copper-oxide rectifier useful up to broadcast frequencies, it was necessary to use small disks and a high current density. The high current density was obtained in part by connecting an inductance in parallel with the rectifier and tuning it with the rectifier capacity. The circuits developed possess unique advantages in that harmonic distortion is practically eliminated, a stage of audio-frequency amplification is eliminated, and automatic volume control of variable , μ tubes as well as other tubes is achieved without the necessity of using an auxiliary tube for volume control. A newform of automatic volume control made possible by the use of a single rectifier element as an asymmetrical resistance is described and discussed.