Editing Point-to-point construction (section)

{{Short description|Making an electronic circuit by directly connecting the leads of the components}}
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[[Image:Motorolagoldenviewchassis.jpg|thumb|Underside of the chassis of a 1948 Motorola VT-71 7" television, showing the complexity of the point to point wiring.]]
[[Image:Antique Radio Coils.jpg|thumb|upright=0.9|Section of a typical Australian late 1930s radio, showing the point to point construction between components.]]
In [[electronics]], '''point-to-point construction''' is a non-automated technique for constructing [[Electronic circuit|circuits]] which was widely used before the use of [[printed circuit board]]s (PCBs) and automated assembly gradually became widespread following their introduction in the 1950s. Circuits using [[thermionic valve]]s (vacuum tubes) were relatively large, relatively simple (the number of large, hot, expensive devices which needed replacing was minimised), and used large sockets, all of which made the PCB less obviously advantageous than with later complex [[Integrated circuit|semiconductor circuit]]s. Point-to-point construction is still widespread in [[power electronics]], where components are bulky and serviceability is a consideration, and to construct prototype equipment with few or heavy [[electronic component]]s. A common practice, especially in older point-to-point construction, is to use the leads of components such as [[resistor]]s and [[capacitor]]s to bridge as much of the distance between connections as possible, reducing the need to add additional wire between the components.

Before point-to-point connection, electrical assemblies used screws or [[wire nut]]s to hold wires to an insulating wooden or ceramic board. The resulting devices were prone to fail from [[Corrosion|corroded]] contacts, or mechanical loosening of the connections. Early premium [[marine radio]]s, especially from [[Marconi Company|Marconi]], sometimes used welded copper in the [[Busbar|bus-bar circuit]]s, but this was expensive. The crucial invention was to apply [[soldering]] to electrical assembly. In soldering, an alloy of [[tin]] and [[lead]] (and/or other metals), known as [[solder]], is melted and adheres to other, nonmolten metals, such as copper or tinned [[steel]]. Solder makes a strong electrical and mechanical connection.

Point-to-point wiring is not suitable for automated assembly (though see [[wire wrap]], a similar method that is) and is carried out manually, making it both more expensive and more susceptible to wiring errors than PCBs, as connections are determined by the person doing assembly rather than by an etched circuit board. For production, rather than prototyping, errors can be minimised by carefully designed [[Standard operating procedure|operating procedures]].

An intermediate form of construction uses terminal strips (sometimes called "tag boards"), eyelet boards or [[turret board]]s. Note that if components are arranged on boards with tags, eyelets or turrets at both ends and wires going to the next components, then the construction is correctly called tag, eyelet or turret construction respectively, as the components are not going from point to point. Although [[Printed circuit board#Cordwood construction|cordwood construction]] can be wired in a similar way the density means that component placement is usually fixed by a substrate that components are inserted into.