Vacuum tube diode is the type that has two electrodes. Diode tube was first created by a scientist from England named Sir JA Fleming (1849-1945) in 1904.
The structure and scheme of the diode can be seen in Figure 7 above.
In the diode, the plate is placed in position around the cathode while the heater is inserted in the cathode. Electrons at the cathode is heated by the heater will move from the cathode toward the plate.
To understand how to work the diodes we can review these three situations are as follows:
- Diodes given a zero voltage
- Diodes given a negative voltage
- Diodes given a positive voltage
In the diode, the plate is placed in position around the cathode while the heater is inserted in the cathode. Electrons at the cathode is heated by the heater will move from the cathode toward the plate.
To understand how to work the diodes we can review these three situations are as follows:
- Diodes given a zero voltage
- Diodes given a negative voltage
- Diodes given a positive voltage
Given a zero voltage diode
When the diode is given tengangan zero then there is no electric field that attracts electrons from the cathode. Electrons are experiencing warming at the cathode is only able to jump up on a position that is not so far from the cathode and form a space charge (Space Charge). No inability of electrons to jump towards the cathode due to the energy given to electrons by heating by the heater has not been enough to drive the electrons reach the plate.
Given a negative voltage diode
When the diode voltage is negative then given a negative potential that existed at the plate will repel the electrons which have formed the cargo space so that the electron will not be able to reach the opposite plate will be pushed back to the cathode, so that no current flows.
Given a positive voltage diode
When the diode is then given a positive voltage potential that is positive on the plate will attract the electrons that had just detached from the cathode by thermionic emission because, in this situation the electric current would take place. How big is the electric current will flow dependent than the magnitude of the positive voltage applied to the plate. The bigger the plate voltage the greater the electrical current will flow.
Because of the nature of this kind of diode that can only drain voltage electric current in certain situations, the diodes can be used as a rectifier of electrical current (rectifier). In fact it is widely used as a diode rectifier AC voltage into DC voltage.
Because of the nature of this kind of diode that can only drain voltage electric current in certain situations, the diodes can be used as a rectifier of electrical current (rectifier). In fact it is widely used as a diode rectifier AC voltage into DC voltage.
Characteristic of the Diode Plate
The most important characteristics of the diodes is Plate Characteristic, where these characteristics provide koorelasi between the voltage across the diode with a current flowing in the diode.
In Figure 11 above can be seen a series of tests (Figure 11.A) to obtain characteristics of the plate and sample plate characteristics of the diode (Figure 11.B).
Heater voltage supplied to the filament to heat the tube until at a certain temperature is T1, and then the plate voltage Eb changed from 0 up to a certain value that can still be handled by the diode. Current Ib flowing in the diode will rise along with increasing voltage on the plate as shown in the graph characteristics of the plate, but when the price reaches a certain Eb Ib it can not rise again and remain constant despite increased Eb continue. Point where Ib can not rise again despite continued elevated Eb called saturation point.
If the filament voltage is increased so that the temperature of the diode to be rising (T2) and performed similar experiments as above again, will get a larger current Ib at saturation point. On the basis of this situation can be concluded that the temperature of the diode can be influential in determining the maximum current that can flow in the diode.
In Figure 11 above can be seen a series of tests (Figure 11.A) to obtain characteristics of the plate and sample plate characteristics of the diode (Figure 11.B).
Heater voltage supplied to the filament to heat the tube until at a certain temperature is T1, and then the plate voltage Eb changed from 0 up to a certain value that can still be handled by the diode. Current Ib flowing in the diode will rise along with increasing voltage on the plate as shown in the graph characteristics of the plate, but when the price reaches a certain Eb Ib it can not rise again and remain constant despite increased Eb continue. Point where Ib can not rise again despite continued elevated Eb called saturation point.
If the filament voltage is increased so that the temperature of the diode to be rising (T2) and performed similar experiments as above again, will get a larger current Ib at saturation point. On the basis of this situation can be concluded that the temperature of the diode can be influential in determining the maximum current that can flow in the diode.
Resistance Diodes
From the plate characteristics that we discussed above, we can see that there is a certain relation between the voltage and current flowing in the diode, based on this fact then we can conclude that the real diode has resistance in the (internal resistance).
Resistance in which is owned by the diode is not the same for AC and DC current provided by the diode so that in connection with these properties then there are two definitions of the internal resistance of the diode is DC and AC Plate Resistance Plate Resistance. Plate DC resistance of the diode resistance is measured when the diode voltage dberikan DC, while AC plate resistance of the diode resistance is measured when the diode is given AC voltage.
To better understand the process of calculation of resistance of the diode can you lihaat figure 12 below.
Figure 12.A show graphs to measure the DC resistance of the diode Plate Plate where the DC resistance of the diode (Rb) is Rb = 0A/0B
Figure 12.b shows the calculation of the AC plate resistance of the diode, because the AC voltage is changed is dynamic or change the value every time the calculation of AC plate resistance must be dilakukakan also taking into account changes in diode voltage and current in some circumstances in this case is the difference in voltage changes and diode voltage.
Plate AC resistance (rb) based on Figure 12.B is rb = (BC / YZ)
Resistance in which is owned by the diode is not the same for AC and DC current provided by the diode so that in connection with these properties then there are two definitions of the internal resistance of the diode is DC and AC Plate Resistance Plate Resistance. Plate DC resistance of the diode resistance is measured when the diode voltage dberikan DC, while AC plate resistance of the diode resistance is measured when the diode is given AC voltage.
To better understand the process of calculation of resistance of the diode can you lihaat figure 12 below.
Figure 12.A show graphs to measure the DC resistance of the diode Plate Plate where the DC resistance of the diode (Rb) is Rb = 0A/0B
Figure 12.b shows the calculation of the AC plate resistance of the diode, because the AC voltage is changed is dynamic or change the value every time the calculation of AC plate resistance must be dilakukakan also taking into account changes in diode voltage and current in some circumstances in this case is the difference in voltage changes and diode voltage.
Plate AC resistance (rb) based on Figure 12.B is rb = (BC / YZ)
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