EOMA68 Computing Devices

An Earth-friendly way to easily upgrade and fix your own computer

Oct 11, 2016

Post-Shenzhen Reflections

by Luke Kenneth Casson Leighton

Much of what I write is off-the-cuff, I don’t know what’s going to be on the page until it’s written. So it’s often interesting, even for me, to re-read things my writing. As I was going back over my previous update on my visit to Shenzhen, it suddenly hit me: everything I’ve done over the past five years - the entire EOMA68 design ethos - is vindicated by this one visit to Huaqiang Road. The process of developing electronics products is not greatly improved by coming over here: it’s something that you have to be very, very careful about in advance. You cannot just pick random parts off of Digi-Key and expect them to be available everywhere. Products are successful, in large part, if they are designed around the most commonly-made components.

But, finding those parts can be a total nightmare. Given a process where you to have scrabble through trays of components in search of a single connector, a process that needs to be repeated for over two hundred components, how can you expect to complete the design in a reasonable time-frame such that it would actually be profitable? This is why I designed EOMA68: so that products could be designed once and only once, and then manufactured without disruption or change for ten years.

You might naively think, "okay, I really want to make a custom SBC product: I’ll use Digi-Key instead despite the fact that it’s five to ten times more expensive, surely it will be possible to shave 80% off when it comes to mass-production, right?” You’ll soon discover, as I found out from Mike today, that components found on Digi-Key (with the easy-to-find datasheets) are often cast-offs from production batches made ten years ago that are no longer in production. Mike is constantly approached by Westerners who give him a design full of Digi-Key-sourced parts, expecting him to be able to mass-produce the design and shave 80% off the cost in the process: the reality is that the only place where he can get the parts is… Digi-Key! So the parts, which originally came from China, have to be shipped back to China with the resultant double VAT and double Customs Duty.

I took Mike along to Runde Electronics today, because I wanted to introduce him to them. When I put the early prototype Micro-Desktop and EOMA68-A20 PCBs on the counter at Runde’s booth, a quiet guy at the back piped up and pointed to the PCMCIA parts, "We have those connectors, too, you know". I was absolutely staggered. They have every single connector and switch that’s needed for the EOMA68-A20, the Micro-Desktop, and the 15.6in Laptop. I asked Mike if this was a normal situation, if he’d ever had a foreign client come over and sit down at only two booths in Huaqiang Road and find absolutely every component needed in only two one-hour visits, he answered resoundingly "No!"

The reason why this happened is very simple: it’s because of the process by which I picked those parts in the first place. I did not sign any NDAs. I did not use Digi-Key, Mouser, or Farnell. I chose extremely common parts where I had very quickly gotten a "feel" for what is commonly available. They are all generic parts. They are all also parts that come from a number of China-sourced Reference Designs.

For example, I picked the CM108AH USB Audio IC because there is a datasheet for it which contains a full schematic which is easily found online. I could have used a "better" USB audio IC, but it would dictate an MOQ of 50,000 units. I then verified that it was mass-produced in huge volumes in USB audio dongles: I distinctly recall buying one ten years ago for $5 USD. The same goes for the GL850G: this hub IC has been manufactured for at least a decade, now. The TDA2822 1W amplifier IC has a datasheet so old it actually has hand-drawn schematics in it. It’s the same audio amplifier that’s been used in cheap transistor radios for over twenty years. I actually had one Chinese designer review the schematics and he said, tellingly, “Ah, you’ve gone old school".

So, bizarrely, after all that fuss, I’m pretty much done. I may have to go back in a few weeks, particularly for the Chicony keyboard, or perhaps to find a Taiwanese supplier. I found the LCD. Got the battery. Got 99% of the components. Mike’s made the Micro-Desktop and EOMA68-A20 PCBs and is going to get the components for them… We’re on the way.


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