Testing Transistors with Ohmmeter

Place the positive lead of the ohmmeter on the terminal indicated by the first subscript on the resistor symbols. (From Simpson, p201). This series of tests is based on the diode nature of the transistor junctions. If all these conditions are met, then at least the diode behavior is functional.

* Between 1 and 10 ohms.

** A thousand or more times the low impedance.

Transistor Maximum Values

Part of the manufacturer's data for transistors is a set of maximum values which must not be exceeded in its operation. These form some of the constraints on transistor operation which are a part of the design of any circuit. A typical set, for the silicon transistor 2N2222:

• Collector-Base Voltage V_CB = 60 v
• Collector-Emitter Voltage V_CE = 30 v
• Base-Emitter Voltage V_BE = 5 v
• Power dissipation I_C V_CE = 500 mW
• Temperature 125°C