Tag Archives: seeedstudio

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RAK833 meets Raspberry Pi

You might have heard about The Things Network (TTN from now on) here or somewhere else. If you have not, then it’s a good opportunity to visit the project and check if there is a community of users around you. I have been a core member of the TTN Catalunya community for over 2 years now. This year we are working hard deploying several new gateways in Barcelona and doing workshops and hackathons with the main goal of helping individuals and social entities to carry out projects around a LoRaWan open, libre (free as in freedom) and neutral telemetry network.

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20171112_185649s

PCB fabs

A few years ago (not many) I used to burn copper plates using acetic acid, a.k.a. vinegar. I was somewhat concerned about using stronger acids so it was OK to use another acid, even if it was soooo sloooow. If you were patient you could get to have decent boards using 50mil traces (or even thinner). But it required keeping a good temperature on the copper bath and regulating the ratio vinegar/hydrogen peroxide continuously, adding a little salt from time to time to speed things up.

The etchant biting the copper

The vinegar biting the copper

One day I saw an article about cheap Chinese PCB fabs (I think it was DirtyPCB by Dangerous Prototypes) and I decided to design my own board and send it to fab. I used Eagle (I still use it although I’m learning KICAD) and the learning process was significant. But at the end I managed to get something. I learned to use copper pours, to correctly label the board, to create my own parts, to avoid auto-route, to use design rules and create gerbers,…

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And over time I have tested different fabs. I’m not an expert by any means but I wanted to write a bit about them here. The basic order I usually do is a 10 units, under 50x50mm board, 1.6mm thick, 1oz copper and HASL Lead Free due to RoHS rules in the EU. The prices and options below are based on these settings.

One more thing. I reckon these suppliers are good enough in most cases for small batches, testing boards or DIY projects. Some EE are concerned about the quality of the boards and they prefer EU-based (or US-based) fabs. I cannot offer a good reason to use these manufacturers here or to not use them in professional/industrial projects.

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20170614_135212s

Solr: digital wrist watch

15 months ago. This is when I started working on this project. The Solr digital wrist watch is a clock that won’t work without a battery but it will neither work without sun. Even more: the vintage display is really cool but it’s hard to read outdoors. A complete nonsense. It is almost a joke and some might easily file it under the “useless projects” label.

But it’s still quite useful. Whether you don’t care about accuracy, or if you need an excuse to always be late. Or maybe you want your daughter to raise her eyebrowns and tenderly call you a “freak”. Either case I suggest you to proudly wear a Solr.

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20170528_105440s

Grid-eye camera (sliced, of course)

Tindie is a great place to find uncommon electronic components or weird/interesting boards. I use to stroll around it’s products to basically see what’s new. It’s like Kickstarted but for real. One such uncommon and new electronic components is the Panasonic’s Grid_EYE AMG88 [datasheet, pdf] infrared sensor. And I first learn about it through Peasky Products breakout board at Tindie.

And if you have been reading me lately you might know I’m going through my own LED fever. My latests “sliced” projects are not the only ones I’m working on at the moment. So it was not surprise my brain immediately linked an 8×8 IR array with an 8×8 LED matrix display. You see?

So what do you have if you throw in a box an IR sensor and a LED matrix, add a small microcontroller, a LiIon battery and a charger and a step-up to power the LEDs? Well, in my case the outcome has been a bulky but nice camera (albeit a very poor resolution one).

I know there are commercially available IR Cameras like this one [Ebay]. They have 300k pixels and can overlay a normal image over the IR image and other fancy stuff, but they are also more expensive (around 200€ the best deal) and waaaaaay less fun to build.

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20170426_224506s

Slices of a clock

There are so many ways to tell the time. DIYers have been doing clocks since the Ancient Egypt (obelisks lacked portability, thou). Every modern maker has a clock amongst her first projects. I have done some myself, including a fibonacci clock, a wordclock with a fancy green matrix effect and an unreleased project that hopefully will see the light someday soon.

But recently I came back to the idea behind the wordclock before, to extend it in different ways:

  • Replace the ATMega328P with an ESP8266 (NTP support and user interaction)
  • Smaller sizes (8×8 LED matrices)
  • Smaller PCB, less buttons
  • Add buzzer for alarms
  • Replace the 3D printed part with a wooden grid cut in laser
  • Completely closed enclosure, better presentation
  • Fix some issues with the original board (like the lack of a beefy capacitor across the LED matrix power lines).

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