How to judge the quality of the bidirectional trigger diode DB3

1. Multimeter for measuring forward and reverse resistance values.

R 1k or R 10k steps to measure bidirectional trigger diodes.

Forward and reverse resistance values. Under normal circumstances, the forward and reverse resistance values should be infinite.

If the measured forward and reverse resistance values are small or 0, the diode has broken down and is damaged.

2. First, use the multimeter to measure the mains voltage U, and then connect the measured bidirectional trigger diode into the AC voltage measurement loop of the multimeter, connect the mains voltage, read the voltage value U1, and then connect the two poles of the bidirectional trigger diode and read out the voltage value U2. If the voltage values of U1 and U2 are the same, but different from the voltage values of U, the conduction performance of the bidirectional trigger diode is symmetrical.

If the voltage value of U1 and U2 is different, it means that the conductivity of the bidirectional trigger diode is asymmetrical. If the voltage values of U1 and U2 are the same as those of the mains U, it means that the bidirectional trigger diode has been short-circuited and damaged. If the voltage values of U1 and U2 are both 0V, it means that the internal circuit of the bidirectional trigger diode is damaged.

The role of the bidirectional trigger diode DB3:

The role of the DB3 diode is to act as a trigger. When the terminal voltage of the DB3 diode reaches 20-30V, the turning voltage of the trigger tube is reached, and the trigger tube is turned on, and the DB3 diode is in a negative resistance state.

DB3 diodes are trigger diodes. Trigger diodes, also known as bidirectional trigger diodes, are two-terminal semiconductor devices with a three-layer structure and symmetry.

It is often used to trigger triacs.

It is used for overvoltage protection and other purposes in circuits.

DB3 is a bidirectional trigger diode. The most basic way to distinguish between good and bad is to check whether the voltage of the bidirectional turning point is qualified according to the test conditions.

Normal between 28V and 36V. Typical is 32V. Also, if you have a graph, see what the dark current is before the transition, the smaller the value, the better.

Your physics teacher takes a look and sees if the physics teacher has any better answers.

DB3 is a bidirectional trigger diode.

When the terminal voltage of the DB3 diode reaches 20 30V, the turning voltage that touches the sock hair tube can be reached, and the tube is turned on, and the DB3 diode is in a negative resistance state.

To understand the characteristics of the trigger diode, we can use a multimeter.

Judge the quality of DB3: Use the R 1K file of the multimeter to measure the forward and reverse resistance values of DB3, and the forward and reverse resistance values are both normal time. If the measured DB3 forward and reverse resistance value is 0 or very high, it means that the DB3 has broken down and short-circuited and damaged the trail footage.

To judge the quality of DB3 more accurately, the method is to measure the mains voltage of the multimeter first, and then connect the measured DB3 into the AC voltage circuit of the multimeter, connect to the mains U, read out the voltage U1, and then read out the voltage U2 after connecting the two poles of DB3, if the voltage value of U1 is the same as that of U2, but different from the mains U, it indicates the conductivity of the DB3 bidirectional trigger diode.

Good symmetry. If the difference between U1 and U2 is too large, the conductivity of this DB3 is asymmetrical. If U1 and U2 are the same, the DB3 is short-circuited. If both U1 and U2 are 0, the internal circuit of the DB3 is faulty.

DB is a bidirectional diode for triggering, the on-voltage is about 30V, and it is not open to the multimeter. The cause of its damage is mostly breakdown, and it can generally be considered that the multimeter is not passable, that is, it is a good product for the year.

However, there are very few broken poles, which can be distinguished by the substitution method (the electricity is higher in its on-voltage, and its withstand voltage can be measured to identify, but most people are not good at it due to equipment reasons).

If the voltage of the measuring diode is higher than 20 volts, it will flash and flash, and if its voltage is lower than the standard value, it will not light up.

Use a multimeter RX10K block to measure the resistance value infinity as normal, and measure the voltage at both ends of DB3.

One end of the table is connected in series to 220V. Meter voltage. It is about the trigger voltage, which is 33V

Connect the base of the transistor and use it as the control end.

A triode like 9013, the most basic control circuit.

The forward and reverse voltammetry characteristics of the bidirectional trigger diode principle are almost completely symmetrical. When the applied voltage U at both ends of the device is lower than the forward transition voltage v(B0), the device is in a high-impedance state. When U>V(B0), the tube breaks down and conducts into the negative resistance region.

Similarly, when you are greater than the reverse turning voltage v(br), the tube can also enter the negative resistance region. The symmetry of the turning voltage is denoted by v(b). △v（b）=v（b0）-v（br）。

Generally, v(b) should be less than 2 volts. There are generally three levels of forward turning voltage values for bidirectional trigger diodes: 20-60V, 100-150V, and 200-250V.

Since the turning voltage is greater than 20V, you can use a multimeter to block the forward and reverse bidirectional diodes, and the watch hands should not move (RX10K), but it is not completely certain that it is good. Check its quality and can provide a power supply with a DC voltage greater than 250V, and the current through the tube should not be greater than 5mA. It is very convenient to use a transistor hipot tester for inspection.

If not, a megohmmeter can be used to measure (one time for forward and one time for reverse) as shown in Figure 6, and the voltage is larger for one time v(br). For example, if a DB3 diode is measured for the first time, and then it is measured to 28V after reverse, then V(B)=V(B0)-V(br)=<2V, indicating that the symmetry of the tube is very good.