How to measure halfgeleiders met a digital multimeter
1. Diodes
The open circuit voltage of the diode gear of the digital multimeter is about 2.8V, the red test lead is connected to the positive, and the black test lead is connected to the negative. When measuring, the current is about 1mA, and the displayed value is the approximate value of the forward voltage drop of the diode, and the unit is mV or V. The forward voltage drop of a silicium diode is about 0.3~0.8V. The forward conduction voltage drop of germanium diode germanium is about 0}.1~0.3V. And the forward voltage drop of the diode with higher power is smaller. If the measured value is less than 0.1V, it means that the diode is broken down, and both forward and reverse conduct. If both vooruit en achteruit zijn open, it betekent dat de PN junctie van de diode is open. Voor licht-uitstraalde diodes, de diode uitzending licht wanneer gemeten in de voorwaart richting, en de buis spanning druppel is ongeveer 1.7V.
2. Transistor
The triode has two PN sections, the emission section (be) and the collector section (bc), which can be measured volgens aan de methode van meten de diode. In de actual measurement, the forward and reverse voltage drop should be measured between every two pins, a total of 6 times, of which 4 times showed open circuit, and only 2 times showed the voltage drop value, otherwise the triode is bad or a special triode (Such as band-stop triodes, Darlington triodes, etc., can be distinguished from ordinary triodes by model). In two measurements with values, if the black test lead or the red test lead is connected to the same pole, then this pole is the base, the smaller measured value is the collector node, and the larger one is the emitter node, because the base has been judged, Correspondence can determine the collector and emitter. At the same time, it can be judged: if the black test leads are connected to the same pole, the triode is PNP type; if the red test leads are connected to the same pole, the triode is NPN type; the silicon tube with a voltage drop of about 0}.6V is a silicon tube, en de één met a spanning druppel van ongeveer 0.2V is a germanium buis. Buis.
Drie, thyristor:
The anode, kathode en controle elektrode van de thyristor zijn open-circuited, based op which the anode pin can be be determined and of the thyristor breaks down can be judged. There also a PN junction between the control electrode and the cathode of the thyristor, but there is a protection resistor between the control electrode and the cathode of the high-power thyristor, and the displayed value is the voltage drop on de weerstand tijdens meting.
4. Optocoupler
One side of the optocoupler is a light-emitting diode, the voltage drop is about 1V when meting, and the other side is a triode, some only lead out c and e, and the positive and negative directions of the measurement are cut off. If all three pins are led out, the measurement characteristics are the same as the above triode (mostly NPN tube). Wanneer a multimeter is gebruikt aan maken de diode geleiding vooruit, at dit tijd, een andere multimeter is gebruikt om meting de geleiding spanning druppel van de triode c aan e, which is about 0}.15V; disconnect the multimeter connected to the diode, and the triode c to e is cut off, aangeven dat de optocoupler is goed
