The working principle of SMD unidirectional thyristor

The working principle of SMD unidirectional thyristor：

The conduction conditions of thyristor: firstly, a forward voltage must be applied between the anode and cathode of the thyristor. Secondly, a forward voltage must also be applied to the control electrode. The above two conditions must be met simultaneously in order for the thyristor to be in a conduction state In addition, once the thyristor is turned on, even if the voltage of the control electrode is reduced or removed, the thyristor still conducts. The thyristor shutdown condition is to reduce or remove the forward voltage applied between the anode and cathode of the thyristor, so that the anode current is less than the minimum maintenance current.

thyristor are divided into unidirectional thyristor, bidirectional thyristors, and unidirectional thyristors with three pins: anode A/cathode middle/control electrode G. The bidirectional thyristors have three pins: first anode A1 (T1), second anode A2 (T2), and control electrode G.

One way is when the current flows through the thyristor in one direction. Therefore, when the current is reversed, the thyristor will not work. To be superficial, it means that the circuits on both sides are disconnected. Therefore, one of its purposes is to stabilize the current (if you want to change the direction of the alternating current, there is only one direction that can pass through) in both directions

The working principle of a bidirectional thyristor can be equivalent to two unidirectional thyristors of the same model being in reverse parallel with each other/then connected in series in a voltage regulating circuit to achieve AC voltage regulation of its thyristor. Of course, one of the main functions of the thyristor is to stabilize voltage and current

Distinguish the K, A, and G poles of a unidirectional thyristor multimeter. First, measure the control pole G and connect the negative meter pen to a certain electrode. 'The positive probe sequentially touches the other two electrodes.' If there is a low resistance value (about a few hundred ohms) and another high resistance value (about a few thousand ohms), it indicates that the negative meter pen is connected to G, and one end of the positive meter pen is connected to the cathode K, and the other end of the positive meter pen is connected to the anode A.