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This article deals with the device used in electronics labs. There is also an article on optical breadboards used in optics labs. For the food preparation utensil, see Cutting board.

A breadboard is a reusable solderless device used to build a (generally temporary) prototype of an electronic circuit and for experimenting with circuit designs. This is in contrast to stripboard (veroboard) and similar prototyping printed circuit boards, which are used to build more permanent prototypes or one-offs, and cannot easily be reused. A variety of electronic systems may be prototyped by using breadboards, from small circuits to complete central processing units (CPUs).

The term breadboard is derived from an early form of point-to-point construction. A breadboard prototype (also known as an evolutionary prototype) is an iteratively designed piece of software designed to evolve into a full-fledged system, whereas a throwaway prototype (often associated with a proof-of-concept) is often discarded.

) is similar to the node pattern of the breadboards shown above.

Evolution Over time, breadboards have evolved greatly, with the term being used for all kinds of prototype electronic devices. For example US Patent 3,145,483 US Patent 3,145,483 Test Board for Electronic Circuits, filed in 1961, granted in 1964, describes a wooden plate breadboard with mounted springs and other facilities. 6 years later, US Patent 3,496,419US Patent 3,496,419 Printed Circuit Breadboard, filed in 1967 and granted in 1970, refers to a particular printed circuit board layout as a Printed Circuit Breadboard. Both examples also refer to and describe other types of breadboards as prior art.

In the early days of radio, amateurs would nail copper wire or terminal strips to a wooden board (often literally a board for cutting bread), and solder electronic components to them. Description of the term breadboard. Sometimes a paper schematic diagram was first glued to the board as a guide to placing terminals, followed by components and wires.

The integrated circuit for the Polaroid camera SX-70 was breadboarded before Texas Instruments fabricated the custom chip. It was rumoured to have been built from discrete components on a 4 ft. x 8 ft. piece of plywood, and was fully functional. The project was so secret that Texas Instruments engineers were only given functional specifications, but not told the purpose of the chip.

Typical Specifications A modern solderless breadboard consists of a perforated block of plastic with numerous tin plated phosphor bronze spring clips under the perforations. The spacing between the clips (lead pitch) is typically 0.1inch (2.54 metre#orders of magnitude). Integrated circuits (ICs) in dual in-line packages (DIPs) can be inserted to straddle the centerline of the block. Interconnecting wires and the leads of discrete components (such as capacitors, resistors, inductors, etc.) can be inserted into the remaining free holes to complete the circuit topology. Typically the spring clips are rated for 1 Ampere at 5 Volt and 0.333 Ampere at 15 Volt (5 Watt).

Bus and Terminal Strips s depicted at the top.These days solderless breadboard of different manufacturers have very similar layouts. The layout of a typical solderless breadboard is made up from two types of of areas, called strips. Strips consist of interconnected electrical terminals. terminal strips:The main area. To hold the electronic components.In the middle of a terminal breadboard strip, one typically finds a notch running in parallel to the long side. The notch is to mark the centerline of the terminal strip and provides limited airflow (cooling) to ICs straddling the centerline. The clips on the right and left of the notch are each connected in a radial way, typically five clips in a row on each site of the notch are electrically connected. The five clip columns on the left of the notch are often marked as A, B, C, D, and E, while the ones on the right are marked F, G, H, I and J. When e.g. a skinny DIL IC is plugged into a breadboard the pins of one side of the chip are supposed to go into column E while the other goes into column F on the other side of the notch. bus strips:To provide power to the electronic components.A bus strip usually contains two columns, one for ground, one for a supply voltage. But some breadboards only provide a single-column power distributions bus strip on each long site. Typically the column intended for a supply voltage is marked in red, while the column for ground is marked in blue or black. Some manufacturers connect all terminals in a column. Others just connect groups of e.g. 25 consecutive terminals in a column. The later design provides a circuit designer with some more control over crosstalk on the power supply. Often the groups in a bus strip are indicated by gaps in the color marking. Bus strips typically run down one or both sides of a terminal strip or between terminal strips. On large breadboards additional bus strips can often be found on the top and bottom of termial strips.

Some manufacturers provide separate bus and terminal strips. Others just provide breadboard blocks which contain both in one block. Often breadboard strips or blocks of one brand can be clipped together to make a larger breadboard.

In a more robust and slightly easier to handle variant one or more breadboard strips are mounted on a sheet of metal. Typically, that backing sheet also holds a number of binding posts. These posts provide a clean way to connect an external power supply. Several breadboard images in this article show such solderless breadboards.

Diagram A "full size" terminal breadboard strip typically consists of around 56 to 65 rows of connectors, each row containing the above mentioned two sets of connected clips (A to E and F to J). "Small size" strips typically come with around 30 rows.

Terminal Strip:

A B C D E F G H I J 1 o-o-o-o-o v o-o-o-o-o 2 o-o-o-o-o o-o-o-o-o 3 o-o-o-o-o o-o-o-o-o ~ ~ 61 o-o-o-o-o o-o-o-o-o 62 o-o-o-o-o o-o-o-o-o 63 o-o-o-o-o ^ o-o-o-o-o

Bus Strip:

V G o o | | o o | | o o | | o o | | o o | | | | o o | | o o | | o o | | o o | | o o | | | | ~ ~ o o | | o o

Jump wires The jump wires for breadboarding can be obtained in ready-to-use jump wire sets or can be manually manufactured. The latter can become tedious work for larger circuits. Ready-to-use jump wires come in different qualities, some even with tiny plugs attached to the wire ends. Jump wire material for ready-made or home-made wires should usually be 22 American wire gauge (0.33 mm²) solid copper, tin-plated wire - assuming no tiny plugs are to be atteached to the wire ends. The wire ends should be stripped 3/16" to 5/16" (approx. 5 mm to 8 mm). Shorter stripped wires might result in bad contact with the board's spring clips (isolation being caught in the springs). Longer stripped wires increase the likelihood of short-circuits on the board. Needle-nose pliers and tweezers are helpful when inserting or removing wires, particularly on crowded boards.

Differently colored wires and color coding discipline are often adhered to for consistency. However, the number of available colors is typically far less than the number of signal types or paths. So typically a few wire colors get reserved for the supply voltages and ground (e.g. red, blue, black), some more for main signals, while the rest often get random colors. There are ready-to-use jump wire sets on the market where the color indicates the length of the wires. These do not allow to apply a meaningful color coding schema.

Advanced Breadboards Some manufacturers provide high-end versions of solderless breadboards. These are typically high-quality breadboard modules mounted on some flat chasing. The casing contains useful equipment for breadboarding. Like, for example one or more power supplies, signal generators, serial interfaces, LED or LCD display modules, logic probes, etc.

Breadboard modules can also be found mounted on devices like microcontroller evaluation boards. They provide an easy way to add additional periphery circuits to the evaluation board Limitations single board computer.Due to large stray capacitance (from 2-25pF per contact point), solderless breadboards are limited to operating at relatively low frequencies, usually less than 10 Megahertz, depending on the nature of the circuit. Solderless breadboards are further limited by their voltage and current ratings.

Also, breadboards usually cannot accommodate Surface-mount_technology devices (SMD). Although sometimes small PCB adapters (breakout adapters) can be used to fit the component on. Such adapters carry one or more SMD components and 0.1" (2.54 mm) connectors in DIL layout. The larger of the SMD components are usually plugged into a socket, where the socket was soldered onto such an SMD adapter. The smaller SMD components are usually directly soldered onto such an adapter. The adapter is then pluged into the breadboard via the 0.1" connectors. However, the need to solder the SMD component or socket onto the adapter contradicts the idea of using a solderless breadboard for prototyping in the first place.

Alternatives Alternative methods to create prototypes are point-to-point construction, reminiscent of the original breadboards, wire wrap, and boards like stripboard. Complicated systems, such as modern computers comprising millions of transistors, diodes and resistors, do not lend themselves to prototyping using breadboards, as sprawling designs on breadboards can be difficult to lay out and debug. Modern circuit designs are generally developed using a schematic capture and simulation system, and tested in software simulation before the first prototype circuits are built on a printed circuit board. Integrated circuit designs are a more extreme version of the same process: since producing prototype silicon is expensive, extensive software simulations are performed before fabricating the first prototypes. However, breadboard prototyping techniques are still used for some applications such as broadband Radio frequency circuits, or where software models of components are inexact or incomplete.

See also

References External links

Java applet breadboard simulator
Crocodile Technology - Electronics simulation program