Prototyping Circuits: Easy Cheap Fast Reliable Techniques

Often there is a need to test an experimental prototype circuit, trying things quickly and cheaply, with predictable performance and reliable results. While it is now remarkably cheap and easy to create PCBs, the turnaround time is often too long. One alternative is solderless breadboards, but they have significant limitations.  Fortunately there are better alternatives.

This post:

  • discusses the ideal properties of “breadboarding” construction techniques
  • illustrates and outlines the characteristics and applicability of various techniques, including cordwood, pegboard, stripboard, matrix board, rat’s nest, dead bug, live bug, manhattan, and some proprietary products
  • shows some examples of their use

Obviously those techniques don’t replace PCBs, but they can be a useful complement during early experimentation and prototyping, and in some cases can be surprisingly permanent.

The TL;DR is to start with manhattan techniques and add other techniques as beneficial. That way you can speedily create predictable and reliable circuits.

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Creating PCBs With Surface Mount Components

I have been creating circuits for mumble years, using wirewrap, IDC and standard PCB technology with plate-thru hole (PTH) components. I’ve recently been “forced” to use surface mount devices (SMD), and was concerned that it would be too difficult for an amateur using only equipment available at home.

I was wrong; it was easy.

On the off-chance it inspires others, here’s what I’ve used, what worked and what didn’t. The tl;dr version is DesignSparkPCB, DirtyPCBs, OSH Stencils, 179C SnPb paste, magnifying visor, *8 lenses, reflow sand in skillet, soldering iron.

Design Layout View

Design Layout View

Also see my techniques for designing, making and assembling homebrew PCBs, and reference material.

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Assembling PCBs With Surface Mount Components

Summary: it does work and isn’t too painful. Naturally I’m evolving methods and techniques as my skill improves.

This outlines how I placed solder paste, placed components, saw small components, soldered and reworked small PCBs. I didn’t want to be constrained by the time it takes to apply solder paste, position components, and reflow in the HackSpace oven, so I looked for ways I could do the whole process at home.

Also see my techniques for designing and making homebrew PCBs, and reference material.

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Manufacturing PCBs With Surface Mount Components

Summary: cheap ‘n cheerful, good enough for double-sided experiments, but not good enough for 4-layer impedance-controlled PCBs.

The laser toner technique and very-low-cost PCB manufacturers are good enough for the low-speed digital signals found in Arduino-class circuits. They are not suitable for large boards, or for containing medium speed digital signals capable of bit-rates up to 1Gb/ or 2Gb/s. A requirement for 50Ω or 100Ω differential impedance lines on >=4 layer PCBs implies the PCB cross-section “stack” must be tightly specified in terms the prepreg’s thickness and \epsilon _r .

This post outlines experiences for small experimental boards.

Also see my techniques for designing and assembling homebrew PCBs, and reference material.

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Designing PCBs With Surface Mount Components

Summary: all the design tools work well.

This describes the tools I used and a constantly-evolving personal style.

I’ve used the free-as-in-beer DesignSparkPCB commercial product from RS running in wine. I didn’t choose Eagle because of its irritating limitations (size, pins etc). I didn’t try KiCAD, and have no opinion about it.

Also see my techniques for making and assembling homebrew PCBs, and reference material.

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