Transistor Tester

Here’s a project that will not only show you how transistors work, it will also let you check any of the transistors you’ll use in the projects in this book.

While the basic circuit has been described to suit NPN transistors (see ‘transistors’ in the section on components at the start of this book); the circuit is very easily modified to check PNP transistors.
You will need these components
Resistors:
One 390 ohms (orange – white – brown)
One 10k ohms (brown – black – orange)
Diodes:
Two light emitting diodes (LEDs)
One protection diode (1N4002 or similar)
Transistors:
One NPN type DS548 or similar
One PNP type DS558 or similar
Miscellaneous:
One battery clip
3 lengths of tinned copper wire
11 self-tapping screws with washers
Baseboard & project overlay No. 2