Transistor Curve Tracer

TRANSISTOR CURVE TRACER T. Wigmore With so many transistors used in today"s equipment, a good tester for these devices is a must in every electronics workshop. And yet, most of us use a multimeter to check transistors. Although such a test is usually adequate for a quick o.k./faulty test, it fails to provide information on the characteristics of the device under test. The curve tracer presented here works in conjunction with an oscilloscope, and is capable of performing a stepped current amplification test on pnp as well as on npn transistors. The instrument so allows unknown or unmarked types to be matched to known ones, which is a frequent requirement in fault-finding and repair work. The so-called output curve is among the most important tran- sistor characteristics. The curve shows how the collector current (on the Y-axis) depends on the collector-emitter voltage (on the X-axis), with base current for the relevant bias setting as a par- ameter. By stepping up the base current ...