Digital multimeters are now a popular electronic measurement tool, and are popular among electronic technicians for their ease of use and accuracy. However, it is often said that when measuring certain components, it is not as convenient as a pointer multimeter, especially when measuring a triode. In fact, I feel that it is more convenient to measure the triode with a digital multimeter.
The inside of the triode can be seen as a combination of two diodes, as shown in the following figure:
Step 1: Determine the base and tube type (NPN or PNP)
As can be seen from the above figure, the base of the PNP tube is the common point of the two negative electrodes, and the base of the NPN tube is the common point of the two positive electrodes. At this point we can use the digital multimeter's diode file to measure the base. For the PNP tube, when the black meter pen (the battery negative pole in the meter) is on the base, the red meter pen is generally a small reading (usually 0.5-0.8) that is not much different from the other two poles. For a larger reading (typically 1). For the NPN tube, the red test pen (the positive electrode of the battery inside the watch) is attached to the base.
Step 2: Determine the emitter and collector
If you use the pointer multimeter to this step, you may need to use both hands, and even a friend will use the tongue, which can be said to be quite troublesome. It is much more convenient to use the digital meter's three-tube hfe file (measuring the triode DC amplification factor) to test the multimeter, hit the multimeter into the hfe file, insert the triode into the small hole of the NPN, and the b pole corresponds to the b letter above. Read; then reverse its other two feet and read again. The polarity of the larger reading corresponds to the letters on the table, and the other transistors are the same!
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