Half-wave rectifier circuit, working principle of half-wave rectifier circuit

Various rectifier circuits composed of crystal diodes .

half wave rectifier circuit

Figure 5-1 is the simplest rectifier circuit. It consists of power transformer B, rectifier diode D and load resistor Rfz. The transformer converts the mains voltage (mostly 220 volts) into the required alternating voltage e2, and then D converts the alternating current into pulsating direct current.

The working principle of half-wave rectifier circuit :

Let’s look at how the diode rectifies from the waveform diagram in Figure 5-2.

The transformer step-down voltage e2 is a sine wave voltage whose direction and magnitude change with time. Its waveform is shown in Figure 5-2(a). Within the time period from 0 to K, e2 is a positive half cycle, that is, the upper end of the transformer is positive and the lower end is negative. At this time, the diode conducts under the forward voltage side, and e2 is added to the load resistor Rfz through it. Within π to 2π time, e2 is a negative half cycle, and the lower end of the transformer secondary is positive and the upper end is negative. At this time, D is subjected to reverse voltage and does not conduct, and there is no voltage on Rfz. Within the period of π to 2π, the process of 0 to π time is repeated, and within the time of 3π to 4π, the process of π to 2π time is repeated again... If this is repeated, the negative half cycle of the alternating current will be "cut off", leaving only the positive Half a cycle passes through Rfz, and a single rightward (upper positive and lower negative) voltage is obtained on Rfz, as shown in Figure 5-2(b). The purpose of rectification is achieved, but the load voltage Usc is. And the magnitude of the load current also changes with time, therefore, it is usually called pulsating DC.

This rectification method that removes the half cycle and the lower half of the figure is called half-wave rectification. It is not difficult to see that half-wave rectification achieves the rectification effect at the expense of "sacrificing" half of the AC, and the current utilization rate is very low (calculations show that the average value of the half-wave voltage obtained by rectification over the entire cycle is the average value on the load The DC voltage Usc =0.45e2) is therefore commonly used in high voltage and small current situations, but is rarely used in general radio devices.