A simple method for distinguishing crystal diodes and the product function of crystal diodes

Crystal diode, also known as semiconductor diode, is a type of diode made of semiconductor materials. Its main characteristic is unidirectional conductivity. In circuits, crystal diodes are mainly used for rectification. In addition, they are widely used in modulation and demodulation, frequency modulation, and frequency division circuits.

A crystal diode is composed of a PN structure, where P is a positive semiconductor and N is a negative semiconductor. In the absence of an external voltage, an electric field called a potential barrier or barrier layer spontaneously forms at the PN junction between the P and N regions. When a forward voltage is applied to the PN junction (i.e., the P region is connected to the positive electrode and the N region is connected to the negative electrode), the potential barrier will be eliminated and the diode will conduct; When a reverse voltage is applied to the PN junction, the potential barrier will increase and the diode will turn off.

The discrimination method for crystal diodes is relatively simple. Firstly, a preliminary assessment can be made based on the appearance characteristics of the diode. Crystal diodes generally have a label indicating the positive and negative terminals of the diode. Secondly, measurements can be taken using a dedicated diode tester or multimeter. In the diode mode of the multimeter, when measuring in the forward direction (with the red probe touching the anode of the diode and the black probe touching the cathode of the diode), if a voltage drop of around 0.5-0.7V is displayed, it indicates that the diode is conducting in the forward direction; When measuring in reverse, if it displays as infinity or exceeds the measurement range, it indicates that the diode is turned off in reverse. If it does not conduct in any direction or conducts in all directions, then this diode may have been damaged.

The application of crystal diodes is very extensive, and their main functions are as follows:

1. Rectification function: In devices such as power adapters and battery chargers, crystal diodes are used to convert alternating current into direct current.

2. Voltage stabilization function: In a regulated power supply, crystal diodes can provide a stable output voltage.

3. Switching function: In various electronic devices, crystal diodes can serve as electronic switches to control the flow of current.

4. Signal detection: In radio receiving equipment, crystal diodes can convert modulated radio signals into audio signals.

5. Protection function: In a circuit, when the voltage exceeds a specific value, the crystal diode can conduct, providing protection against circuit component burnout.

Overall, crystal diodes are an indispensable part of electronic devices, and their development and application have driven the progress of modern electronic technology.