Breadboard
From Wikipedia, the free encyclopedia
- 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 PCBs which are used to build more permanent prototypes or one offs and cannot easily be reused. Usually breadboards have strips (known as bus strips) down one or both sides either as part of the main unit or as separate blocks clipped on to carry the power rails. Sometimes there is a sticky foam backing and this will often cover the back of the entire assembly as sold even though the breadboard itself is in several parts.
A modern solderless breadboard consists of a perforated block of plastic with numerous tin plated phosphor bronze spring clips under the perforations. ICs in dual inline (DIP) packages can be inserted to straddle the centerline of the block. Interconnecting wires and discrete component leads can be inserted into the remaining free holes to complete the circuit topology. Using these it is possible to prototype a variety of electronic systems, from small circuits to complete central processing units. However, due to large stray capacitance (which have been reported from 2-25pF per contact point), solderless breadboards are limited to operating at relatively low frequencies, say less than 10 MHz, depending on the nature of the circuit.
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[edit] Naming history
The breadboard derives its name from an early form of point-to-point construction. 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. Sometimes a paper schematic diagram was first glued to the board as a guide to placing terminals, components and wires.
[edit] Alternatives
Alternative methods to create prototypes are point-to-point construction, reminiscent of the original breadboards, wire wrap, and Boards like stripboard.
Prototyping with breadboards is too clumsy and unreliable for complicated systems, such as modern computers comprising millions of transistors, diodes and resistors.
Modern circuit designs are generally developed using a schematic capture and simulation system, and tested in 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 specialised applications such as broadband RF circuits, or where software models of components are inexact or incomplete.
[edit] Software Engineering
A breadboard prototype (also known as evolutionary prototype) is an iteratively designed piece of software designed to evolve into a full-fledged system. This contrasts with a throwaway prototype (often associated with a proof of concept) that is discarded.
[edit] Trivia
The integrated circuit for the Polaroid SX-70 camera 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.
