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  • Author Author: Gough Lui
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When PCBs Are Cheaper Than Lunch, Build PCBs! A DA-15 & Banana to Terminal Block Breakout

Gough Lui

It wasn't all that long ago that I took the step to get myself acquainted with KiCad and start designing PCBs for manufacture in my spare time - in fact, just two years ago. But since then, I could not have imagined that vendors such as JLCPCB could build five two-layer 100x100mm PCBs and ship them to my house for between AU$8.50 to AU$9.00. For comparison, a McDonalds Small Big Mac meal runs about AU$11.90 as of today in this inflationary environment. This is something I could have never imagined, growing up making PCBs by hand and being told that a double-sided board was already a luxury. Now we get soldermask and silk-screening as part of the deal, along with delivery from China! Sure, it takes about two to three weeks to arrive, but that's a small price to pay for the big saving in shipping cost.

As a result, I spent a bit of time building some solutions to my small annoyances. The first is to do with the DA-15 connections on the back of R&S NGL/NGM/NGU/LCX units for the digital I/O which I never seemed to have any connectors for. This resulted in this breakout which could theoretically work for any DA-15 connection, but the silkscreening is especially helpful for those R&S instruments -

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It is a trivial board to design. It was built with components sourced from element14 - the full project and gerbers are at https://goughlui.com/2022/10/02/project-da-15-d-sub-breakout-for-rs-ngx-lcx-digital-i-o/. A quick look at the BOM reinforces how the component cost makes the PCB cost literally insignificant.

The second addresses the annoyance of a lack of binding posts on modern test equipment. Sure, the shrouded banana serves a function in protecting users from high voltages - but if they aren't around, or aren't in use, then perhaps we should have a way to get away with connecting bare wires as that's often cheaper and more convenient.

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That resulted in this four-way banana to 5.08mm terminal block break-out. Not a perfect design, but it does the job just fine for me - https://goughlui.com/2022/10/02/project-banana-to-terminal-block-breakout-or-where-are-my-binding-posts/. Once again, the parts costs dwarfs that of the PCB, but it does solve a real problem and makes my life quite a bit easier.

So, perhaps what I'm trying to say is ... PCBs are so cheap now, even with the international shipping, that perhaps we can stop obsessing about making things perfect and just send through designs for prototyping whenever it takes our fancy. It's literally "lunch money" but the result may well be more valuable in terms of hassle avoided or things learned. But perhaps the first thing one needs to learn is a bit of patience ... cheap shipping is almost always never going to be fast!

Hope this has been useful - you can build them, at your own risk. If you'd like a board, perhaps you can ask me although I would suspect the cost for me to ship it to you would outweigh the cost of just ordering them built and shipped to you directly!

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  • I have been using PCBs for prototyping for 2 decades now because the price became affordable (less than 100 dollars per order). In that period the price has come down form 50 dollars per card to 50 cents per card. Now that SMT parts are ubiquitous, PCBs are really the only thing that makes sense or cents. I now consider it an ugly imposition when I have to resort to using strip board, even though I still have a soft spot for it. I usually design between 8 and 18 PCBs per year, although some of them are as simple as connector adapters. At this rate I am often ordering the next PCB before the previous one arrives, so there is always something on the go.

    The shipping cost from China has jumped from 3 dollars to between 15 and 30 dollars, which can put it perilously close to the old 50 dollar price, so I have to cut down on ordering frivolous PCBs. Actually one place used to ship for "free" and their PCB cost was about 1 dollar per card.

    Likewise if I can't 3D print all the mechanical parts because something gets too hot for plastic or whatever, I throws me into a quandary.

  • in reply to dougw

    I now consider it an ugly imposition when I have to resort to using strip board, even though I still have a soft spot for it.

    Every time I start to use any form of protoboard, I get about 3 or 4 connections in, and then I wonder why I didn't just make a PCB! :)

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