Digital multimeter for the detection of diode-on voltages
In this gear, the red pen is connected to the internal positive power supply of the multimeter, and the black pen is connected to the internal negative power supply of the multimeter. The connection between the two pens and the diode. If measured according to the connection method, the measured diode is conducting, the multimeter displays the diode's positive conduction voltage, the unit is mV. usually good silicon diode positive conduction voltage should be 500mV ~ 800mV, good germanium diode positive conduction voltage should be 200mV ~ 300mV. if "000" is displayed, it means that the diode breaks down and short-circuits, if "000" is displayed, it means that the diode breaks through. If "000" is displayed, it means that the diode is short-circuited, if "1" is displayed, it means that the diode is not available in the forward direction. If "1" is displayed, it means that the diode is inverse cut-off, and if "000" or other values are displayed, it means that the diode has been inverse breakdown. This file can also be used to determine the good and bad triode and pin identification. Measurement, first a pen connected to a identified pin, another pen is successively connected to the remaining two pins, if so measured twice are on or are not on, and then replace the two pens and then measured, both are not on or are on, it can be determined that the transistor is good, and can be determined that the identified pin is the base of the transistor. If the red pen is connected to the base, the black pen were connected to the other two poles are on, then the transistor is NPN-type, and vice versa, is PNP-type. Finally, compare the size of the two PN junction positive conduction voltage, the reading is larger be junction, the reading is smaller bc junction, thus the collector and emitter are identified.
