Electronic circuit: how does the triode divide its poles? How does a multimeter measure the quality

Triodes exist in almost any electronic circuit. It is necessary for every electronic technician to understand and be familiar with the basic properties and measurement of triodes.

Although it is simple, it is hard for novices to learn. Today, we will focus on the principle, classification and use of triodes and how to quickly distinguish the quality of triodes by using a multimeter.