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Starting electronics
Figure 10.7 Possible breadboard layout of the circuit in Figure 10.6
The integrated circuit used is a type of integrated circuit
called a CMOS device, and it’s in what’s known as the 4000
series of integrated circuits — it’s actually known as a 4049.
Don’t worry about this for now, as we’ll look at more devices
in the series (and another series, for that matter) later in the
chapter. All you need to know for now is that it’s a standard
dual-in-line (DIL) device, so you must be careful that you
position it correctly in the breadboard.
Making sure that the actual integrated inverter used in our
circuit has the correct input (that is, either logic 1 or logic
0) is easy. Logic 1 is effectively the same as a connection to
the positive battery supply — in practice though, you should
never connect an input ‘directly’ to the positive battery supply;
instead always connect it using a resistor. On the other
hand, logic 0 is just as effectively the same as a connection to
the negative battery supply (this time though, it’s perfectly
allowable to connect an input directly). In other words, when
the inverter’s input is connected to positive it’s at logic 1:
when connected to negative it’s at logic 0.
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