Dynamic development of electronics systems was greatly influenced by the introduction of semiconductor element, which is developed in the first half of the twentieth century the bipolar transistor. The bipolar transistor consists of three semiconductor layers with different conductivity type (p-n-p or n-p-n), which results in two types bipolar transistors – PNP and NPN. The individual layers are their names: e – emitter, B – base, C – collector. The basis of application of the transistor is the dependence of the value of a larger current flowing between connector and emitter-collector, from changing the value of a smaller current flowing in the connector, the base-emitter.


Fototranzystor in theory

Using the photoelectric properties of semiconductors, invented a modified version of the transistor – fototranzystory. In fototranzystorach current value in the connector, the emitter-collector current is not governed by the base-emitter, but the light intensity falling on this connector. Photons falling on the connector, the base-emitter characteristics, additionally polarize them in the direction of conduction, causing current flow in the connector emitter-collector, the value of which depends on the luminance value. In the condition without illumination, the transistor does not conduct current through the connector, the emitter-collector that is synonymous with a state of disconnection. Given the lack of need of power supply connector the base-emitter electric current fototranzystory have, as a rule, only two output emitter and collector. Also available fototranzystory where the derivative base, and you can control it like a conventional transistor bipolarnym. Fototranzystorów advantage over other elements fotoelektrycznymi, such as fotorezystory much shorter switching time / answers, and much more sensitive.

Parameters fototranzystorów

If you want to choose the right fototranzystory for your applications use the characteristics prądowo-voltage manufacturer at the same time, by selecting the operating point, fototranzystora suitable for Your needs. An important parameter is the wavelength for which fototranzystor gets maximum sensitivity. In Botland, you will find fototranzystory with maximum sensitivity at a wavelength of 570 nm, 870 nm, 925 nm, 940 nm, which coincides with the range of radiation in the visible and infrared.


Fototranzystory because of the very high sensitivity and speed are used in the detection of radiation, where a large brake system, thus, in measurement systems with high speed, as analog to digital converters, models connects optoelektronicznie. They can be used as optoizolator for the exchange of signals between two electronic systems. Check offer Botland and find out what opportunities are fototranzystory!