Category Archives: Analysis


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,…


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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Yet another WiFi light bulb

Eight months ago I reviewed and hacked the AiLight WiFi light bulb by AiThinker. By the time there was a number of people doing the same because of a key reason: it sports an ESP8266 microcontroller and it is based on the OpenLight by Noduino, that had already provided open source code for the LED driver inside, the MY9291.

Let time pass and I was doing the same with the Sonoff B1 light bulb by Itead Studio. That was two months ago and the conclusion was that the AiLight is brighter the the B1 but the lacks warm white channel the Sonoff bulb has.

And now here I have yet another WiFi light bulb, the Arilux E27 Smart Bulb. It looks pretty much like the other two, same shape, same microcontroller, same driver, but different base again and most important: different LEDs. So how does this one compare to the other ones?

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Sonoff B1, lights and shades

Six months ago I was reviewing the AiThinker AiLight, a great looking light bulb with an embedded ESP8266EX microcontroller, driven by a MY9291 LED driver. Just before summer IteadStudio released it’s Sonoff B1 [] light bulb, heavily inspired (probably same manufacturer) by the AiLight, at least on the design.

Now that IteadStudio has become popular between the home automation community you can also find the Sonoff B1 on global marketplaces like Ebay or Aliexpress for around 13€.

A closer look at the B1 uncovers some important differences. But before going deeper into the details let me first say that this post will probably look more like a review, at least more than I use to write. And second, yes: ESPurna supports the Sonoff B1 🙂

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A closer look at the H801 LED WiFi Controller

Some weeks ago I talked about the Magic Home LED Controller as I was adding support for it in my ESPurna firmware. At the time a user pointed me to the H801 Led WiFi Controller by Huacanxing. The user in question (Minh Phuong Ly) even did a pull request with some preliminary support for it. So I decided to give it a go.

The H801 is a 5 channels controller that you can find for about 9-10€ at Ebay or Aliexpress. It’s slighly more expensive than the Magic Home Led Controller (you can find the later for 7€ at Aliexpress) but it also is quite different from the insides…

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Fenderino, the coolest guitar

Last February 7 I attended a workshop at a the SokoTech in Barcelona to assemble my own Fenderino, the coolest guitar ever (my knowledge about guitars is very limited, so take this sentence with a grain of salt).

The guitar is actually a shield for the Arduino UNO and has been designed by the people at, an initiative aimed to provide open(-sourced) tools for educators, created amongst others, by David Cuartielles, co-founder of Arduino. The shield is inspired by the works of two very good friends of mine: Marc Sibila (@marcsibila) and Jordi Divins (@jdivins). You really should be following these guys, they are doing very special things as Instròniks.

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