The Ferro-Resonant Flip-Flop.--A ferro-resonant flip-flop was described by Carl Isborn of the Computer Research Corporation, Hawthorne, Calif., at the recent I. R. E. convention. The individual unit consists of an inductance in series with a capacitance and a low resistance. The reactance of the inductance is non-linear and decreases with increasing current. The value of the capacitance is chosen to resonate with the inductance at some intermediate value of current. Then, as current is increased, the voltage across the circuit will increase, then tend to decrease until the resonant point is reached, and finally increase. By applying an a-c. signal pulse, the current corresponding to a particular voltage can be made to jump from the lower value to the higher value. Reversal of the process is achieved by suppressing the voltage across the unit and forcing it to a value below the bi-stable state.
The device lends itself to the construction of ring counters since it requires very little more power to operate a 10 position ring than a 2 position flip-flop. Another advantage of the unit is that no vacuum tubes are required.