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Starting electronics
IC series
For most people, there are two families of ICs that are used in
digital electronics. The first is a very easy-to-handle variety
(in other words, they can’t be easily damaged). On the other
hand, they require a stable operating voltage of 5 V, which
isn’t all that easy to generate, without a power supply.
The second family of digital ICs will operate over a range of
voltages (typically, a 9 V battery does the job exceedingly
well), but are a little more easily damaged. Nevertheless,
handled carefully and correctly, both families work well.
7400 series
The 7400 series of digital ICs is the variety that requires a
fixed 5 V power supply. While there are many, many devices
in the family only a few are of interest here. Before I explain
about the ICs in detail though, a brief word about the 7400
series numbering.
The first two digits of any device in the family (that is, 74--)
indicate that the device is a member of the family. The 7400
series is a family of digital ICs known as transistor–transistor
logic (TTL) devices. The last two (or sometimes three) digits
(--00) indicate which IC this is in the family. In other words a
7400 (which happens to be an IC with four, two input NAND
gates) is different to a 7402 (which has four, two-input NOR
gates).
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