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  • Author Author: dougw
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The Missing Link (BBC-PCB)

dougw

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Background

I recently used breadboards in a couple of projects and rediscovered some of their utility as well as many of the myriad reasons why I stopped using them years ago.

I started to list all the reasons why I was turned off breadboards, in a humorous way, but humor isn't my strong suit and after 17 reasons it wasn't all that funny any more, so I won't repeat them all here, but feel free to add your pet peeves in the comments below..

There has been an explosion of small MCU modules that have breadboard friendly pinouts, including many Arduinos, Infineon PSoC4 & 5, several Adafruit Feathers, ESP32, Sparkfun Thing Plus, Teensy, etc. which generally are only large enough to have a USB connector on them. A vast number of sensors and peripherals also use 0.1" pitch inline connectors to claim compatibility with these modules, and breadboards are a quick way to lash these all together to test a complete system. This all means breadboards still have a lot of usefulness in quick prototyping.

It dawned on me that if I am going to make use of them, I had better do something to improve the process and get the most out of the experience.

The title of this blog addresses one of the key barriers to using them from my perspective - the issue of how to connect them to the rest of the world.

I call this lack of easy connection the Missing Link between breadboards and other instrumentation.

 

Bare BBC-PCB

The solution I came up with is a BreadBoard Connector Printed Circuit Board (BBC-PCB). I actually designed a couple of variants to add different connector complements.

The first BBC-PCB I designed includes a suite of connectors that I typically might need to connect breadboard circuitry to external instrumentation and peripherals.

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The second BBCPCB I designed can be built as an audio-centric connector interface or as an instrument-centric interface, or a mix of both. This is because there are 3 locations where the card can have either a BNC connector or an RCA connector.

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Both PCBs include banana jacks, pin jacks, a USB connector, a 3.5mm stereo jack, 2 slide switches, a push button switch, a potentiometer, an LED, at least 1 BNC connector, and at least 1 RCA jack. One card includes a barrel jack while the other one can have a couple of extra BNC or RCA jacks.

The signal traces for all these components are routed on the top layer, it is easy to see which pin they are connected to on the breadboard. The breadboard pins are also labelled on the slikscreen, if you don't want to follow the traces.

One card has vertical banana jacks, so it can be butted up against another card.

Both cards have the same mounting hole arrangement, so they can be swapped if a different connector complement is needed.

 

Example Usage of BBC-PCBs

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Portable Breadboard Kit

BBC-PCBs are one of the subjects covered in this blog, but I wanted to improve beyond just better interconnection, so I decided to make up a portable breadboard kit.

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I expect to mainly use breadboards in blogs to do quick demonstrations, so some aspects of a good breadboard kit are about photgenics, but mostly it is about ease and speed of use.

Incidentally, the Project14 display module is based on a Raspberry Pi Pico.

 

This video describes some of the kit components and and how it can all be portable:

 

Speaker Test Setup

To provide an idea of the utility of the BBC-PCB, I put together a little demo to test the difference between 2 speakers with the same dimensions but different cone technology.

Here is a picture of the test setup:

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The following video describes the Portable Breadboard Kit, the BBC-PCBs and how clean and easy it is to connect a lot of instrumentation to a breadboard using BBC-PCBs.

The final video shows how practical it is to use BBC-PCBs to perform test like this speaker test. It also shows that not all speaker technologies sound the same.

Discussion and Conclusions

When I started this project, I had hopes that it would turn out to be something I use regularly. I am happy to conclude the system actually turned out to work better than expected. I haven't used it much yet, but as usual when working through a new test, I had to adjust the setup as I discovered more about the subject. The simple feature of having the cards securely screwed to the base plate provides a confidence-inspiring solid feel to the system. The BBC-PCB connector system really showed excellent flexibility in allowing changes to be made quickly and easily with stock cables and all the cabling remained manageable and relatively clean. I couldn't be happier with the results.

The design phase was fairly extensive since I had to design multiple PCBs and at least a dozen 3D printed parts. And the project took much longer than expected since I had to wait anxiously for quite a few parts that seemed to take for ever to arrive.

Fortunately all the PCBs and all the 3D printed parts worked great without modifications.

Quite a lot of work went into making the blog presentable, from the missing link animation to the Raspberry Pi Pico based Project 14 sign, but the sign is re-usable and of course the BBC-PCBs are specifically designed to be reused.

It is funny how much work one does (like this whole project) to avoid doing just a little bit of extra work (while breadboarding).

 

Swag Idea

I think this BBC-PCB idea would be very useful for anyone using breadboards, which includes a pretty large fraction of the maker population.

These BBC-PCBs only cost $0.50 each, so I thought they would make a great swag give-away item that element14 could use as a promotional gadget. I know I would rather get an item like this as a give-away than a coffee mug.

I could add some element14 branding to the card artwork and element14 could order their own batch to give away (since I am not interested in the logistics of selling them).

For a more expensive version, say as part of a contest kit, it could include a kit of connectors.

If you think this would make a good swag item, be sure to say so in the comments below.

Also if there is a connector you feel needs to be on the card, indicate it below.

 

Relevant Links:

This Device Tickles My Fancy

DIY Test Instrumentation

Tenma Handheld DC Power Supply - Review

Raspberry Pi Pico - Review

Strip Board -works with BBC-PCB

Project14 | Winners Announcement: Doing It Yourself Test Instrumentation!

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