When you build an experimental circuit on a breadboard socket, you will
need to insert various components into the contact holes on the socket
itself. In some cases you can use such components as resistors and
capacitors to directly interconnect the appropriate pins or leads of
transistors or ICs. In other cases you will need to complete your
connetions with short lengths of hookup wire, commonly called
"jumpers."
In all cases, however, there are some basic rules for handling
experimental components and preparing them for use in your circuits. These
rules were developed over time, to help avoid some problems which are
often encountered with this type of circuit construction.
The basic rules you should always be careful to follow are:
- Always keep your work neat. You will often have to locate a
particular point or component in the circuit, to make a measurement or try
a component of a different value. It's much easier to do this if your work
is neat and easy to trace.
- Keep your component leads short. Component leads are
uninsulated. If you keep them long, you'll have them continually bumping
into each other and causing short circuits in your experiments. In
addition, long leads tend to get messy and make it hard for you to check
your assembled circuit.
- Use different colors of jumpers for different kinds of
functions. The insulation on hookup wire comes in many different
colors. It is typical to use red wire for connections to +5 volts and
black wire for connections to ground. Beyond that, the choice is up to
you. In a digital circuit, you might want to use (for example) green wire
for the system clock. That way, you can find and check all of your clock
connections quickly and easily.
- Avoid both overcrowding and excessive spacing. A circuit that
will remain in place over a series of experiments (such as a set if LEDs
as logic state indicators) should be built compactly so as to take up as
little room on the breadboard socket as possible. But the experimental
circuit itself should be constructed to allow easy access to components
and test points. On the other hand, if you spread things out too much, you
might not have enough room for all of the required experimental
components.
- Never force components into the breadboard socket contacts.
This is especially important with multi-pin ICs, such as 14-pin and 16-pin
dual-in-line packages (DIPs), but also applies to individual component
leads. IC pins can easily fold up underneath the package so you can't even
see that it isn't making contact. If it resists insertion, pull it back
out and try again. As you gain practice, you'll find a workable technique.
As for individual component leads, it may help to use diagonal cutters to
shorten the leads a bit. This will also cut a wedge-shaped point onto the
new end of the lead, which will be easier to insert.
- Never bend a component lead at the body of the component. See
the figure to the right. These are two ¼-watt resistors with their
leads bent to fit snugly on a breadboard socket. The resistor on top has
its leads separated by ½ inch, or 0.5". The lower resistor is
shaped to space its leads 0.3" apart. Both distances are very
practical for use on breadboard sockets. Beware the temptation to just
bend the leads at the resistor body to get 0.3" separation. The body
of a ¼-watt resistor is just the right size to suggest this.
However, if you bend a component lead right at the component body, you run
the risk of damaging the component or even tearing the lead completely
off. Play it safe and do a little extra shaping, if necessary, to get your
components to fit snugly.
- Leave at least ¼" of lead length available to plug
into the breadboard socket itself. A length of ¼" will
allow the component to fit snugly against the breadboard socket. If you
need the component to sit up off the breadboard socket, ust at least
½" to ¾" to help hold the component up. Typically,
you'll want semipermanent assemblies to be small and neat, with components
settled down. The actual experimental circuitry might call for components
to be raised up a bit for easier grasping and
replacement.
If you always handle your experimental components gently and with
respect, they will last a long time and provide excellent service. It is
never too early to learn proper care for your tools and parts.
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