Paper details

1 Introduction

A solderless breadboard is a construction base for prototyping of an electric circuit. It is also called as a protoboard or a plugboard or a simply breadboard. On the surface of it, there are many tiny holes which are aligned as matrix. These holes are to insert electric parts as resistors, capacitors, diodes, transistors, coils, ICs, and so on. Horizontal lines of these holes are electrically connected each other and vertical lined holes are not connected. Because of that connection, it is possible to make prototype of an electric circuit without soldering these parts each other, and it is also easy to remake a circuit. This is the reason why the breadboard is useful to learn how to make a circuit and how it works. A lot of students who study engineering in the tertiary education use the breadboard, some textbook in the field of robotics introduces breadboard as a first step of making a system[1]. Figure 1 shows an example of circuit using normal breadboard and electric parts.

Figure 1: An example of electric circuit using breadboard

By the way, our university is unique one which accepts only visually impaired and hearing impaired students and there is a lecture class in the field of mechatronics for the visually impaired students. In this class, students try to make a circuit using breadboard and weakly sighted students can enjoy learning it. However, for students with severe visual impairment including totally blind, it might be really difficult to search right position of the hole and insert tiny parts to it. To solve this problem, a large breadboard kit with electrical parts were developed and tried to use it in this class.

2 Features of developed breadboard kit

The basic idea of the developed breadboard is simple. It is just to enlarge original breadboard using banana plugs and jacks, and adding Braille information. Blind person can find right position touching the Braille. Figure 2 shows an overview of the developed breadboard kit. To fit for the enlarged board, electric parts also should be enlarged by connecting banana plugs with cables. The connecting point between cables and terminals of the electric parts is covered by heat-shrinking rubber tube to insulate and avoid shorting them, but not covered the body of the parts. It is important point and one of the features of the developed kit. Keeping original shape of the electric parts enables students to touch it and understand what it is. There are several electrical block systems of consumer version in the market[2] and they can construct arbitrary circuit, but these blocks are completely covered and visually impaired student cannot understand real shape of the parts. 

The other feature is that the length of cables and its color. For example, transistor has three different terminals called emitter, collector, and base. These terminal lengths are same and difficult to distinguish. Therefore I make the lengths and colors of cables different so that visually impaired students can distinguish them. The same strategy is applied to the parts which have polar character, like capacitor or electrical buzzer. 

Figure 2: An overview of developed breadboard kit for the visually impaired students

3 Trial using of the kit

Developed kit was used in the class of mechatronics in our university mentioned above. The contents of the lecture included making transistor circuit and logical circuit using 74 series of IC. Students with severe visual impairment could construct these circuits only by themselves.

References

[1] COOK, David. Robot Building for Beginners, 2010. Springer. ISBN 978-1-4302-2749-6.
[2] http://otonanokagaku.net/products/kit/index.html