IDENTIFYING TRANSISTOR LEADS
Some case styles of transistors permit the leads to be quickly identified. The TO 5 and TO 18 cases, and the TO 3 case are in this category. The leads of the TO 5 or TO 18 case transistors can be identified by holding the case of the transistor with the leads
facing you as shown in Figure 52–12A. The metal tab on the case of the transistor is closest to the emitter lead. The base and collector leads are positioned as shown in Figure 52–12A.
The leads of a TO 3 case transistor can be identified as shown in Figure 52–12B. With the transistor held with the leads facing you and down, the emitter is the left lead and the base is the right lead. The case of the transistor is the collector. Several case styles for the transistor are shown in Figure 52–13.