1, the role of the varactor diode is a semiconductor device utilizing a variable capacitance between the PN junction made of the principle, as a variable capacitor for use in high frequency tuning, communications circuits. Belonging to the varactor diode reverse biased diode, a reverse bias voltage to change on the PN junction, can change the PN junction capacitance. The higher the reverse bias junction capacitance the less, the inverse relationship between the bias voltage and junction capacitance is nonlinear, as shown at right. 2, illustrating the relationship between the varactor diode and the capacitance value of the reverse bias values: (a) a reverse bias voltage increases, resulting in reduced capacitance; (b) reducing the reverse bias voltage, resulting in increased capacitance. Error range is a predetermined capacitance varactor capacitance range. Data table will display the minimum, nominal and maximum values, which are often painted in FIG. a, visually judge semiconductor diode polarity: general physical circuit diagram can be seen through the eyes of a semiconductor diode direct positive and negative in the physical end to see if there is a color-coded negative, the other end is positive. b, judge with a multimeter (pointer table) semiconductor diode polarity: usually use a multimeter ohm (R * 100 or R * 1K), and then were two tables with a multimeter pen out separately received a single two-pole diodes light-emitting diodes, when the diode conduction, the measured resistance is small (generally between tens of ohms to several thousand ohms), then the black pen then the positive monochromatic LED light-emitting diode manufacturers, the red pen then the negative diode. When measuring the resistance of a large (typically a few hundred to several thousand ohms) monochromatic light-emitting diode, when the black pen then the negative diode, the red pen then the positive diodes. c, test note : When using a digital multimeter to measure the diode, the diode red pen then the positive characteristics of monochromatic light-emitting diodes, the negative black pen then the diode, when measured resistance is diode forward conduction resistance, which is a pointer multimeter pen then the law is just the opposite. Qingdao monochromatic light emitting diodes | monochromatic light emitting diodes | gold credit provided by the Science and Technology Industrial Co., Ltd. Qingdao integrity. Integrity Technology Co., Ltd. Qingdao (www.qdjcx.com) strong, credible, in Qingdao, Shandong diode industry has accumulated a large number of loyal customers. The company better work attitude and constantly improve the integrity of innovative ideas will lead the gold into the brilliant and you work for a better future!