In this paper the author considers the operation of a tunnel diode circuit in which the parameters permit self-sustained oscillations to occur. A set of response relations are derived which characterize the numher, frequency, and amplitude of these oscillations. These response relations are analyzed graphically. Using these graphs a method for operating the tunnel diode as a bistable memory device in the present case when oscillations can occur, is explained. The stable modes of operation are a stable oscillation and a stable steady state. These stable operating modes are separated by an unstable oscillation. © 1962, IEEE. All rights reserved.