Digital multimeter diode conduction voltage detection
In this position, the red test lead is connected to the positive power supply inside the multimeter, and the black test lead is connected to the negative power supply inside the multimeter. The connection between the two test leads and the diode is shown in Figure 1. If it is measured according to the connection method in Figure 1 (a), the diode under test is conducting forward, and the multimeter displays the forward conducting voltage of the diode in mV. Usually, the forward conduction voltage of a good silicon diode should be 500mV to 800mV, and the forward conduction voltage of a good germanium diode should be 200mV to 300mV. If "000" is displayed, it means that the diode is short-circuited, and if "1" is displayed, it means that the diode is not forward. If it is measured according to the connection method in Figure 1(b), it should display "1", indicating that the diode is reversely cut off. If it displays "000" or other values, it indicates that the diode has reversely broken down. This file can also be used to judge the quality of the triode and identify the pins. When measuring, first connect one test lead to a designated pin, and connect the other test lead to the other two pins successively. Change two test leads and test again. If they are not turned on or both are turned on twice, it can be confirmed that the triode is good, and it can be confirmed that the identified pin is the base of the triode. If the red test leads are connected to the base and the black test leads are respectively connected to the other two poles, it means that the triode is NPN type, otherwise, it is PNP type. Finally, compare the magnitude of the forward conduction voltage of the two PN junctions. The one with the larger reading is the be junction, and the one with the smaller reading is the bc junction. From this, both the collector and the emitter are identified.
Triode value beta test
First of all, it is necessary to determine whether the triode to be tested is NPN type or PNP type, then insert its pins into the corresponding type of test socket correctly, and turn the function range switch to the β position, that is, the β value can be read directly from the display screen. "000", it means that the triode is broken.
short circuit detection
Turn the function and range switch to the "•)))" position, and the two test leads test the points respectively. If there is a short circuit, the buzzer will sound.
