Topic 24. Transistor Switches
There is a basic transistor switch on p. 78. Now look more closely at these switching circuits and how to design them.
A transistor switch makes use of the BJT’s most important property — gain. There is more than one way of defining gain, but here we mean the small signal current gain, hfe, described on p. 88. Gain has no units. It is just a number, because it is a current divided by a current. The gain of a typical BJT is 100.