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An Ugly Construction Workbench Contents: 1. Introduction
I stopped making printed circuit boards (PCBs) a long time ago. Apart from being messy to produce, the 'printed' wiring made it difficult to substitute component types, or modify the basic design. Rather than making it easy to build projects and try different circuits, I found that PCBs hampered experimentation. Eventually, 'ugly construction' became my preferred method for rapidly transferring suggested circuits into working projects. Although ugly construction is most often used for prototyping, it is also possible to use these same construction techniques to produce the final version; such that projects are assembled quickly; are reliable in use; look good; are easy to maintain; and easy to modify. With care, the finished item really can look very presentable - so good, in fact, that the very term 'ugly construction' becomes a misnomer!
Typically, ugly construction involves building circuits just above the copper surface of a piece of copper clad board. (Copper clad board is the material used for making PCBs, prior to etching away the unwanted areas of copper foil). If using double-sided copper clad board, components are often mounted on both sides. Of course, whether using single or double-sided board, components can still be mounted on both sides of the board to increase the component density. Interconnecting leads and wires may be passed through small holes that have been drilled through the board - but be sure to de-burr the hole on both sides with a few turns from a much larger drill bit. Small components will be held in place adequately using only the soldered connections. For some components, such as wire-ended crystals and large ferrite cores, I use double-sided sticky pads, or hot-melt glue to ensure that they remain firmly anchored to the board. Inductors in metal cans (e.g. Toko coils) can be mounted on their side, and its earth tag soldered directly to the copper foil. ICs may be placed upside-down ('dead bug' fashion) on the foil side. Also, 'walls' of copper clad board are often used to screen one part of the circuit from another. The positioning of the components on the board usually follows the layout implied by the suggested circuit diagram, with all earth connections being made directly to the copper foil. It couldn't be easier! Once a few of the components needing an earth connection have been soldered in place, the other interconnecting components are simply soldered 'lead-to-lead' to their neighbours. When you're building the final version of a project, you may wish to crop the leads quite short to reduce the chance of short circuits, and to save space. Standoff insulators can be used as anchor points for interconnections with other boards; front panel controls; and equipment sockets. I ran out of standoff insulators many years ago; so, these days, I solder one end of a high value resistor to the foil, and use the other end as a 'poor man's standoff insulator'. I also use high value resistors to provide additional component support by soldering them between the foil and a lead of the component.
The illustration above depicts my ugly construction workbench. The base consists of a piece of white 'melamine' faced chipboard, measuring 300 x 150 mm. To the left, I have mounted an old three-gang variable capacitor (500pF per gang). A pre-drilled aluminium front panel is mounted on the front edge of the base, which allows for the fitting of potentiometers; variable capacitors; switches; and other controls. Similarly, a back panel is fitted to the rear edge of the base, and fitted with sockets and power connectors. A piece of copper clad board is then polished (using brass polish) before being fitted to the base, foil side uppermost. This construction aid will be large enough for most small projects. For larger projects, simply connect more sheets of copper clad board around the basic workbench. When prototyping my 80 m transceiver, I ended up with about
3000 cm2 (3 sq ft) of ugly construction. And yet the final version of the rig was
eventually built into a case measuring only Further Information 136 kHz QRP TX - includes pictures at both at the prototype stage, and the final version. 60 m QRP TX - includes a picture of this 5 MHz rig at the
prototype stage. For more excellent
photographs of ugly construction, see:
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