Ferrite-Transistor Cell

a pulse component in devices used in automation and computer technology, comprising one or more ring-shaped, square-loop ferrite cores combined with a transistor. The simplest type has a single core with the following: one or several write windings, one or several read windings, and an output winding, on which a readout signal appears when the core undergoes magnetic reversal. The transistor amplifies the signal and segregates the circuits in order to prevent the undesirable passage of signals in the reverse direction when several cells are connected in series. In the static state the transistor is blocked by a bias voltage. In writing, the signal in the output winding increases the transistor cutoff further; in reading, the signal in the output winding compensates the effect of the bias voltage, and the unblocked transistor amplifies the readout signal. Each cell is enclosed in an individual case to form an independent module.

Ferrite-transistor cells are free of many of the inherent drawbacks of ferrite-diode cells; they are simple and reliable, and they have good performance characteristics. However, their response speed is relatively low (~10⁵ reversals per sec). In the 1960’s, ferrite-transistor cells were used for logic elements developed for specialized digital computers; they have also been used in automation equipment, such as frequency dividers and shift registers, and in remote control devices. However, complexity of manufacture has restricted the production rate, and the cells have been used infrequently since the appearance of integrated microcircuits.