Let's talk about electronically controlled lamps.
What are electronically controlled lamps?
Electronically-controlled lamps are electrical devices with a certain number of electrodes that pass electric current in only one direction. The name of the lamp depends on the number of electrodes: diode (two electrodes), triode (three electrodes), pentode (five electrodes), etc. They are used in radio engineering, electronics, energy and many other industries, as a rule, to correct an alternating electric current , and also affect the frequency of the current, act as a detector and switch electric circles. You do not know what a diode and triode are for? Let's start correcting this gap.
Diode
The diode is an electronically controlled lamp in which there are two electrodes. The diode and triode on the hardware component differ precisely in the number of electrodes, remember this. Based on the physical principles of the functional implementation, they are divided into such types (accordingly, each type is divided into a number of subspecies):
Vacuum. Used to rectify current. When the cathode is heated to the required temperature (when thermoelectric emission occurs), a voltage positive relative to the cathode is applied to the anode. Then part of the released electrons goes to the anode and a diode current is formed. If this does not happen, then the electrons return to the cathode.
Gas discharge. Used for amplifiers of significant power and stabilization of large voltages. They are a cathode and anode that are placed in an inert gas or gas mixture under a certain pressure.
Semiconductor. The application possibilities are very diverse. They are devices in which the electrical transition is rectified and there are two external terminals. As a rectifying electric transition, an electron-hole transition, a metal-semiconductor contact, or a hyperjunction are used.
Triode
Unlike a diode, a triode, in addition to the anode and cathode, also has a control electrode, which is called a grid. The grid located between the anode and cathode makes it possible to control the electron flow in the lamp by changing the size and polarity of the voltage between the grid and the cathode. It is because of this ability that the grid is called the control.
The grid, in most cases, is a spiral of thin wire that surrounds the cathode. They make it from nickel, molybdenum, their alloys, as well as from tantalum and tungsten. The lower the potential in the grid, the more work the electron must do to pass the field. At certain negative voltage values, not a single electron can cross the grid field, and the anode current of the triode will be zero. Triodes are often used to amplify a signal when receiving a radio beam.
Practical use
The triode and diode, the physics of their use made it possible to qualitatively step forward the development of everything related to electricity. It is difficult to imagine radio receivers, televisions, computers, telephones and many other things without them. A diode and triode are used not only in large-scale production, but also by amateur radio amateurs and radio electronics in their home experiments. It is difficult to imagine an advanced printed circuit board that will drive sophisticated technology, and which will not have electronically controlled lamps. The diode and triode have a very wide range of uses, so the presence of several unused these devices for any radio amateur is almost guaranteed. But in their practical use, you should be careful - these are devices that work with voltage, even if they are small, but if you ignore safety precautions, the consequences will be at least unpleasant.