EXPERIMENT E0 BREADBOARDS E0.1 OBJECTIVE The objective of this experiment is to familiarize the student with breadboards and their use in connecting up or hard-wiring a circuit quickly without doing any soldering. This is a very short experiment and is, therefore, to be done together with Experiment 1. E0.2 CONCEPTS The term breadboard (more commonly called prototype board in Europe) refers to a plastic board (Fig. E0.) with rows of holes in it into which the wire ends of electronic components as well as wire patch cables can be inserted. These holes have springy metal clips inside the board (Fig. E0.2), which are not visible from outside, that provide the function of tightly holding metal wire insertions into them. Thus, the springy metal clips provide a good electrical contact between the clips and the inserted wires or components. Furthermore, groups of these metal clips are interconnected in the backplane of the board so that, within a group, all the interconnected holes are electrically the same point. The purpose of the breadboard is to enable a quick assembly of an electrical circuit so that the circuit performance can be tested. In real world, the design of an electronic circuit involves prototyping the circuit that is conveniently and quickly done on such a breadboard since no soldering is required. Clearly, changes of components which often takes place in the design and testing process can be effected easily and quickly if no soldering is required. After the design process is completed, the manufacture of the circuit is usually done using printed circuit boards. The origin of the term breadboard in the context of solderless assembly of electrical circuits is unknown to the author but this is how the American Heritage Dictionary of the English Language (4th Edition, 2000) defines the term: 1Fig. E0.1. Schematic showing the top view of a breadboard 2Fig. E0.2. Schematic of a metal clip comprised of five springy inserts which are independent of each other , i.e., one can insert the end of a wire into any one of the inserts without affecting the tension in the other inserts. The clip is made of nickel silver is a good conductor, is non-corrosive and provides good spring effect NOUN: 1. A board on which bread is sliced or dough is kneaded. 2. An experimental model, especially of an electric circuit; a prototype. 3. A thin, blank, often white board on which a prototype circuit with numerous connections for circuit elements is constructed. TRANSITIVE VERB: Inflected forms: bread·board·ed, bread·board·ing, bread·boards To construct an experimental model of (an electric circuit, for example). OTHER FORMS: bread board ing —NOUN 3The analogy to a board on which bread is sliced or dough is kneaded would appear not to be a very sound one. On the other hand, the term prototype board does convey the message that the board is used for assembling a prototype circuit. Fig. E0.3. Show electrical interconnections between the holes by drawing solid lines through them 4E0.3 EXPERIMENT E0.3.1 Perform continuity tests using an ohmmeter in order to identify the internal electrical connections of the holes in the breadboard. Show these internal connections on the breadboard schematic given in Fig. E0.3. E0.3.2 Show how you would hook up the circuit of Fig. E0.4 on the breadboard given in Fig. E0.5. Fig. E0.4. DC circuit whose layout is to be done on the breaboard given in Fig. E0.5 5Fig. E0.5. Breadboard on which the circuit of Fig.E0.4 is to be laid out.