Uncategorized – www.mattos.eng.br

07/09/202607/09/2026Uncategorized

Going down the crypto mining rabbit hole – #1 cpu mining

I don’t know why, but these days I had this urge to mine bitcoin. Not sure why. I’m usually interested in bitcoin from the investment point of view, when it is cheap I buy, when I understand that it is stretched, I sell. Mostly through ETF instead of trading the coins. I could manage to make few bucks operating like this over the years. I’m by no means a “crypto bro” and/or a believer that bitcoin is some sort of savior and/or the solution for every problem on earth’s surface. Nonetheless, I find it an interesting concept, and kinda resonates […]

03/01/2026Uncategorized

pwrTools.app

Dear fellow engineers, I have great news! I’d like to invite you to try out my new electrical engineering tools hub, hosted at https://pwrtools.app . The idea is to make widely available some of the applications I’ve been developing to support my daily work over more than a decade of professional practice and research. To bootstrap the platform, I have included four tools: 1. serFilt: Series filter design tool. Its purpose is to quickly prototype filters for use in power quality studies; 2. LTparam: Overhead transmission line parameter calculator based on the physical description of the conductors and their position […]

18/07/201730/11/2017Uncategorized

TL-WR841ND + OpenWRT: Success!

My fiancée’s TP-Link TL-WR841ND (v9) router was systematically crashing when under heavy load, especially with Torrent. It was only possible to return the router to operation by power cycling it. I had tried to update its firmware with the newest version avalaible from TP-Link’s website. Nonetheless, it was not enough to solve the presented issue. In order to avoid launching this router through the 4th floor window, as last resort I tried to reflash it with OpenWRT. Here is the wiki page dedicated to this cheap router: https://wiki.openwrt.org/toh/tp-link/tl-wr841nd. As far as I can tell its been a success! The router […]

21/03/201722/03/2017Uncategorized

Launch pyjulia with Julia static compiled linux binary

Follows the Python script to launch pyjulia using Julia static compiled GNU/Linux binary installed in an arbitrary path.

23/02/201723/02/2017Uncategorized

Fixing Nvidia + Bumblebee + Dell L502X error in Ubuntu 16.04

For some weird reason the Ubuntu 16.04 Bumblebee’s default version was not being able to switch on/off my discrete video card NVIDIA Corporation GF108M [GeForce GT 540M]. I was getting the following error: $ optirun glxgears [ 7224.163607] [ERROR]Cannot access secondary GPU – error: [XORG] (EE) [ 7224.163722] [ERROR]Aborting because fallback start is disabled. I was able to solve the aforementioned issue in this way: 1) Adding the repository with fresh bumbleblee packages: $ sudo add-apt-repository ppa:bumblebee/testing 2) Updating the repositories and upgrade bumblebee: $ sudo apt-get update; sudo apt-get upgrade 3) Adjusting /etc/bumblebee/bumblebee.conf file: 4) Adjusting the /etc/bumblebee/xorg.conf-nvidia , […]