CHAPTER 16 ■ TRANSISTOR SWITCHES
Testing with a Multimeter that Has a Transistor Socket
When using a meter with a transistor test socket, you’ll need to test the transistor differently depending on
whether you have access to the transistor’s datasheet.
Testing a Transistor When You Have the Datasheet
If you have access to a transistor’s data sheet, then you already know a lot about the transistor. You know
whether it is NPN or PNP. You know which lead is the emitter, the base, and the collector. You also know
approximately how much it can amplify, which is called “gain.”
Since you already know the transistor type and pinouts, you’d probably be testing to determine if the
transistor is working and to compare its gain to other transistors in the same batch.
- Turn the multimeter dial to hFE (see Figure 16-2) or the appropriate function for
your meter. - For a 2907A transistor, Figure 16-3 shows the correct insertion. All of the
transistor leads are inserted on the PNP side of the socket. The emitter connects
to ‘E,’ the base connects to ‘B,’ and the collector connects to ‘C.’
Figure 16-2. Dialing the transistor gain test (hFE) on a multimeter
Figure 16-3. Inserting the 2907A into the multimeter transistor test socket (examples from two different
sockets found on various meters)