Post story worth Edison.This inquisitive man of science experiment with his incandescent bulb, trying to reach new heights in the electric light, and accidentally invented the diode lamp.In a vacuum, the electrons leave the cathode and carried away in the direction of the second electrode separated by a space.About rectified current at the time knew little, but the patented invention over time found its application.It was then, and needed a volt-ampere characteristic.But first things first.
current-voltage characteristic of any electronic device - vacuum, as well as semiconductor and - helps to understand how to behave when you turn on the device in the circuit.In fact, this dependence of the output current from the voltage applied to the device.Edison invented the predecessor of the diode is designed to cut off negative stress, although, strictly speaking, it will all depend on the direction of the instrument is switched into the circuit, but more about that some other time, in order not to tire the reader with unnecessary detail.
Thus, the current-voltage characteristics of an ideal diode is a positive mathematical branch of the parabola, known to most in school lessons.The current through such a device can flow only in one direction.Of course, the ideal is different from real life, and in practice at low voltages there is still a parasitic current, called the inverse of (leakage).It is substantially less than the desired current, referred to as direct, but, nevertheless, forget the non-ideality of real instruments should not be.
vacuum triode different from his younger brother with the two electrodes by the presence of the control grid, partitioned across the mid-section of the vacuum flask.A cathode with a special coating that facilitates separation from the surface of the electron, was a source of elementary particles, which took the anode.Flow control voltage applied to the grid.The current-voltage characteristics of a triode vacuum diode lamp is very similar, but with one big specification.Depending on the voltage at the base of the parabola coefficient undergoes a change, and it turns out the family lines of similar shapes.
Unlike diodes, transistors operate at a positive voltage between the cathode and the anode.The desired functionality is achieved by manipulation of the grid voltage.And, finally, do the latest update.Since the cathode has a finite ability to emit electrons, each has a saturation characteristic in which a further increase in the voltage no longer leads to an increase in the output current.
Despite the different nature and principles of the current-voltage characteristics of the transistor is not too different from the triode, but the steepness of the parabola is relatively large.That is why the lamp circuit on reflection is often transferred to the semiconductor substrate.The order of physical quantities other than the transistors are much smaller supply voltages.Moreover, semiconductor devices can be controlled by both positive and negative voltages, which gives a greater degree of freedom of the designers when designing circuits.
to meet requests for the transfer of ready-made solutions and devices have been invented with the photoelectric effect.However, if the lamp used its foreign species, the advanced element base, for obvious reasons, based on the internal functioning of the photoelectric effect.The current-voltage characteristic photoelectric characterized in that the output current value is shifted, according to the light.The light intensity is higher the greater the output current.So work phototransistors and photodiodes used the reverse current branch.This helps to create equipment capable of detecting photons and controlled by external sources of light.
