transistor selector

transistor selector elektor october 1983 This transistor selector will enable you to determine the class — A, B, or C - into which a transistor falls. The class is defined by the d.c. current gain, hFE, as follows: class A: hFE up to 200 class B: hFE 200 .. . 400 class C: hFE above 400 This is roughly the same classification as used by manufacturers on low-power transistors. transistor selector Figure 1. The circuit for checking n-p-n transistors. The coding of the LEDs corresponds to the usual classification of the d.c. current gain. Figure 2. Compared with figure 1, the circuit for p-n-p transistors appears up-ended. The differences between the two are explained in the text. 1 10-62 The classification A, B, or C, given by manufacturers in their data books does not always indicate exact values. Normally, the three classes are given minimum, maximum, and typical values, and therefore they overlap to some extent. It may sometimes be necessary to check the class printed on the tra...