how to detect a two-way trigger diode?
how to detect a two-way trigger diode?
use the multimeter to place the multimeter in the RX1~RX10kQ gear and measure the positive and reverse resistance of the bidirectional trigger diode.When it is normal,it should be infinity (because the forward and reverse voltage and reverse voltage are greater than 20V.that is larger than the cell voltage in the meter).In measurement, if the meter pointer swings,the damaged tube can not be applied.
it is shown that the turning voltage diagram of the bidirectional trigger diode is a circuit diagram of the circuit for judging the turning voltage of a two-way trigger diode.The DIAC can be replaced by a MEM table instead of the power supply.
According to the specific turning voltage of the bidirectional trigger diode, the multimeter is placed in the corresponding voltage shift,and two values,one VBO and a Ver, are compared with the V.The smaller the difference between the absolute values of the two,the better the better the symmetry of the bidirectional trigger diode is.In use, because the turning voltage of the bidirectional trigger diode has a symmetrical characteristic,it can be chosen from the data obtained in two times - the value is VBO, and the other is VBR.
what is a varactor?
Variable capacitance diode is made of special materials.When the voltage is added to PN junction,the power supply capacity will change.
The symbol and equivalent circuit shape and characteristic curve are shown in Figure,
where C is PN junction capacitance and Rj is
PN junction reverse resistance,R,resistance for semiconductor materials, L, and C, respectively, are distributed inductors and capacitors.
The voltage and current characteristics and internal structure of varactor are the same as those of ordinary diode.
Under reverse bias voltage, varactor shows larger junction capacitance. The capacitance of this junction capacitance C can vary with the magnitude of the reverse bias voltage. The higher the reverse voltage, the smaller the capacitance; the smaller the reverse voltage, the greater the capacitance. The capacity of the varactor diode junction capacitance Cj varies with the applied reverse bias voltage.
If a varactor with a certain DC reverse voltage is applied to the loop of the oscillator, the junction capacitance of the varactor can be achieved.
The oscillation frequency of the oscillator can be controlled by adjusting the voltage of the resonant loop capacitor.The main parameters of some commonly used flake varactors are shown in table.