Electronics Hardware Prototyping

Introduction

A prototype is an early sample, model, or a product built to test a concept or process. A prototype is generally used to evaluate a new design to enhance precision by system
analysts and users. Prototyping serves to provide specification for a real, working system rather than a theoretical one. Prototyping can either be in a physical form, such as in drawings or 3D modelling, or using software to simulate proposed real-world performance of the concept.

In this course we will look at electronic project prototyping, with focus on hardware prototyping. In another course, we will look at how to prototype our electronic projects using software such as Proteus and Fritzing. Firstly, we will look at prototyping boards. We will learn how to use the solderless breadboard for temporary prototypes, Vero board for more permanents versions, and Printed Circuit Boards (PCB) for more advance and permanents projects. We will also look at how to power your components, and then common connectors used.

Pre-requisite for this course include the basic understanding of the concept of electricity, electronic components, and how to translate circuit diagrams, as this is the initial steps before you begin prototyping. Luckily, we have different courses in this platform covering these topics.

Boards

Breadboard

A breadboard is a construction base for prototyping of electronics. A modern solderless breadboard socket (invented by Ronald J Portugal) consists of a perforated block of plastic with numerous tin plated phosphor bronze or nickel silver alloy spring clips under the perforations. The clips are often called tie points or contact points.

The spacing between the clips (lead pitch) is typically 0.1 inches (2.54 mm). Integrated circuits in dual in-line packages (DIPs) can be inserted to straddle the centerline of the block. Interconnecting wires (such as jumper and DuPont cables) and the leads of discrete components (such as capacitors, resistors, and inductors) can be inserting into the remaining holes to complete the circuit. The edge of the board has male and female dovetail notches so boards can be clipped together to form a large breadboard.

Typical breadboard showing IC placement

Solderless breadboards connect pin to pin by metal strips inside the breadboard. The layout of a typical solderless breadboard is made up of two strip areas, known as: Terminal strips and Bus strips.

Terminal strips:
This is the main area that hold most of the electronic components. This area is erpendicular to the centerline.

Bus strips:
This is used to connect the breadboard to a power source. A bus usually contain two columns: one for ground and the other for supply voltage. Typically the row intended for supply voltage is marked red, while the row for ground is marked blue or black.

Breadboard layout showing strip connection

Breadboard diagram showing Bus strip

Some manufacturers provide high-end versions of solderless breadboards. These are typically high-quality breadboard modules mounted on a flat casing. These casing contains additional equipment for prototyping, such as power supply, signal generators, serial interfaces, LED display or LCD modules, and logic probes.

pros

Because the solderless breadboard does not require soldering, it is reusable, making it easy for creating temporary prototypes and experimenting with circuit design.
It is also suitable for beginners who have little experience with PCB design and soldering.

cons

Breadboards have high resistance, and less reliable connections, which are subject to jostle and physical degradation. Signaling is also limited to about 10 MHz.
Modern surface-mount technology devices (SMD) or components with grid spacing more or less than 0.1 inches (2.54 mm) can not be used on breadboards. So, you either prototype with the through hole version of that component, or you solder the SMD components to small PCB adapters called "breakout adapters" then connect or fit the adapter to the breadboard.

Veroboard

Another board for electronic project prototyping is the Veroboard. Veroboard is a brand of stripboard, a pre-formed circuit board material of copper strips on an insulating bonded paper board. It was introduced as a general-purpose material for use in constructing electronic circuits. This types of wiring board may be used for initial electronic circuit development, to construct prototypes for bench testing or in the production of complete electronic units in small quantity.

With Veroboard, components are suitable positioned and soldered to the conductors to form the required circuit. Veroboard has two common types, which are: Line type and Dot type. The line type has track (conductor) linking an array of component holes on each line. While the dot type has conductor at surrounding each hole. In the Line type Veroboard, breaks and cuts can be made in the tracks, usually around holes, to divide the strips into multiple electrical nodes. In the dot type, components are connected using wires or component leads.

Line-type Veroboard

Dot-type Veroboard

Veroboard is not designed for surface-mount components, though it is posible to mount many such components on the track side.

pros

Suitable for semi-permanent prototyping.
Used for prototyping advanced electronic projects.
Useful for practicing your soldering skills.

cons

Used by more experienced makers.
Requires some circuit design and soldering skills.
Working with Veroboard requires carefulness, as correcting already soldered part is not so easy.

A stripboard(Veroboard) and similar prototyping printed circuit boards cannot easily be reused.

Printed Circuit Board (PCB)
A printed circuit board (PCB) mechanically supports and electrically connects electrical or
electronic components using conductive tracks or pads. Although PCBs are usually used in the finished electronic products, there can also be used for prototyping, such as in professional looking prototypes for presentation. Today, the cost of making a printed circuit board is affordable making it a choice for DIY prototyping.

Typical Printed Circuit Board (PCB)

pros

Suitable for advance prototyping.
Gives room for neat prototyping as connecting wire are minimal or completely eliminated.
Suitable for both prototyping and finished product.

cons

More costly than the previously mentioned prototyping boards.
Not suitable for beginners.
Requires good design and soldering skills.
A PCB is designed only for a particalar project and can not be reused for another.

Connectors and Cables

Pin header
A pin header (or simply header) is a form of electrical connector. It consist of one or more rows of male pins typically spaced 2.54 mm (0.1 in) apart. The distance between pins (measured from center to center) is known as pitch.

Different types include: Male pin header, Female socket header, and Box header. They find application in electrical and electronics projects, prototyping not excluded: such as in Arduino boards for connecting external circuits. They can also be used on breadboards.

Male pin header

Female header socket

Box header connector

Jumper wire
A jumper wire (jumper for short) is an electrical wire, or group of them in a cable, usually with a connector or pin at each end. They are normally used to interconnect the components of a breadboard or other prototypes, without soldering. Jumper wires are connected by inserting their "end connectors" into the slots provided in a breadboard, the header connector of a circuit board, or a piece of test equipment.

Male-Male jumper wire

Different types of jumper wires exist having different connectors attached to their ends. Some common connectors include: Solid tips, Crocodile clips, Banana connectors,
Registered jack (RJnn), RCA connectors, RF connectors, and RF jumper cables.

Dupont cable
Dupont is also called Jumper Wire. But, unlike the "traditional jumper wire" which male connectors at each end, dupont cable can have different connectors, such as male-male,
female-male, female-female connectors at their ends. There are also usually in groups, hence the name "Dupont cable". The name is derived from the manufacturer of the connector type they possess.

Male-Female Dupont cable

Powering your components

You need a source of power for your electronic project to come to life. This source of power
that gives life can also be the source of death to your project. You need to know the amount of power your project need, as too much or too low energy can cause damage to your components. You also need to the type of signal: whether AC or DC current, but since we are dealing with electronic circuits, we most likely convert any form of current to DC current.

Choosing the right amount of energy

To know the suitable amount of energy to supply your project, you need to know the component with the highest power rating. For example, if you are making a simple project to regulate a stepper motor, the stepper motor should be the component with the highest power rating. Assuming your stepper motor power rating is 6V, then a 9V power supply should do.

Let's look at the different ways to power your components in prototyping and even in finished products.

3.3V/5V Output MB102 Breadboard Power Supply Module Board
You can power the breadboard using simple jumper wires connected to the bus strip section of the breadboard, but, using the breadboard power supply module is an advance and more suitable way of doing so.

Breadboard power supply unit

Power supply unit fitted on a breadboard

This Breadboard power supply has 3.3/5V selectable output on two channels. The maximum current can be drawn is 700mA. The selection of the output voltage is independent on each channel and the user can select the output voltage by changing jumpers separately. For power input, a DC barrel socket and USB-A socket is available for
powering up the module. There is also an ON-OFF switch available along with a power-on status LED. You can use a 6.5-12VDC power supply to power up the module through the DC barrel socket.

Other power connectors suitable for powering the breadboards, Veroboards, and PCBs include: JST connector, Molex connector, Header pins, DC barrel jack, Pin Screw Terminal connector, USB (for advance projects) etc.

Pin screw terminal connector