Components 129be designed around four resistors and a capacitor as well as the usual input and output
coupling capacitors. However, there are two main reasons to use the integrated circuit
(IC). The amplifi er’s performance is infl uenced by the transistor’s parameters, not so
with the IC. Coupling the transistor amplifi er into a following stage requires careful
consideration of the loading effect. An IC-based amplifi er just gets coupled into the next.
The IC amplifi er is such an effortless pleasure to use. The input, output, and gain are so
nicely controlled. You would have had to have labored through the transistor’s design
quirks to really appreciate how much more controlled the IC is.
Transistors come in a huge variety of types, from general-purpose, small signal (the most
common) to large power devices. The frequency range of operation can extend from DC
to audio all the way up into the microwave range. Transistors are not as easy to evaluate
as ICs. Put together a few resistors and capacitors around an IC and you’ll soon know
if the circuit is working (and it usually is), as you don’t have to even wonder if the IC
itself is working. However, try the same with a transistor, and you’ll fi nd that determining
whether or not the circuit is working is a lot harder. Was the transistor the right type? Was
the bias network correct? Is the circuit design right? If the transistor circuit doesn’t work,
you’ll always wonder whether the transistor itself is okay for the application. Isn’t it great
to know that in the majority of cases, you need only ask for one IC (the LM 741 as it
turns out) when working with ICs. Enough said about transistors. They have their uses in
specifi c applications, but you’ve got to be a bit more circuit smart.
4.1.5 Other Components
4.1.5.1 Integrated Circuits
The integrated circuit is an amazingly robust bullet-proof device, by which I mean that
you can put practically any design around the IC and know that it is going to behave
itself—okay, behave itself within reason, but ICs are brilliantly transparent compared
to transistors. A small handful of resistors and capacitors and, hey, presto, we’ve got a
well-behaved amplifi er. The transistor could never match that! I know the comparison is
a little unfair, especially because the IC itself is composed of a very carefully designed
collection of transistor-based circuits, but we’re talking user-friendliness here. I recall the
diffi culty I experienced way back in the mid-1960s getting a simple half-watt transistor
power amplifi er to function properly. The component count was high, special parts were
diffi cult to come by, setup was tricky, and current consumption was high. Now we’ve got