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Introduction
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 connections 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, leave 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.
