Increasing Sensitivity of Sensors-Converters of Light and Magnetic Field Based on Unijunction Transistor

Generators based on unijunction transistors (UJT) are used as sensors of light and magnetic fields, the output parameter of which is generation frequency depending on a measured value. This paper shows experimentally the possibility of a significant increase in sensitivity of such sensors by connecting a bipolar transistor (BT) in a connection variant with an open base in the UJT emitter circuit; the current of this BT is dependent on a light flow and magnetic field. Such a generator based on UJT and BT can be used as a radiation and magnetic field sensor. The UJT can also be applied in industrial optical couplers, where it is an input element with contactless control by the alternation of LED. The possibility of additional contactless control of the optic coupler with an external magnetic field extends their functional possibilities.