How to use / navigate this blog

This is a quick summary of how to use / navigate this blog.


Sep. 24, 2018: The broken HTML Sitemap has been fixed. Hope it will help you find what you need faster...

Auto Translation by Google Translate

Use the Select Language widget to translate this blog into the language of you choosing (the translation quality may not be good, but I think it's enough to give you some general idea about the post).


How to create and prepare design for CNC machines (laser cutter, milling machine, router, etc)

This is a quick write up about how to create and prepare designs for CNC machines (laser cutter, milling machine, etc).

The software tools used are SketchUp and Inkscape.


1. The use of Sketchup is not a must. However, if you have a 3D design and you want to produce it using materials cut with laser cutter / CNC milling machine, it would be easier to first do the 3D design in Sketchup, convert it to 2D, then export the 2D design in SVG format for further process in Inkscape.

2. There are at least 2 file formats supported by Inkscape that could be used by CNC machines. One is PDF (it could be imported and used by CorelDraw), the other is DXF. If you plan to use DXF format, be sure to install the latest Inkscape (v1.0) because the scaling of the objects saved in DXF format is incorrect (too small) in the previous versions. More about this could be found in the link below.

3. Some shops will ask you for design file in DWG format. You could either use PDF to DWG converter (not all of them are free and some of the converted results are not so good or have a watermark on them) or ask whether they could take file in DXF format instead.

Scaling issue saving DXF from Inkscape

The Sketchup Part

Step-1: Launch Sketchup. Before starting the design, be sure to set the Camera to "Standard Views - Top" and enable "Parallel Projection".


Arduino IDE - How to update the arduino core of the installed board

This is a quick write up on how to update the Arduino core of ESP32 and ESP8266 in Arduino IDE.

1. Navigate through Tools -> Board -> Boards Manager.


How to measure power supply noise

I recently built a power supply board using LM2596S-3.3 and I wanted to find out about its output noise. Below is a quick write up on how I did it with my RIGOL DS1102E scope.

Wiring Diagram

First, wire up the DUT (LM2596 Board) and the rest of the equipment according to the below diagram.


ESP32 - OTA firmware update using Arduino IDE

This post is a quick write up of me following the instructions provided by G6EJD on how to do OTA firmware from inside Arduino IDE.

His instruction video can be found at the link below:


Here is the link to his GitHub page for this project: https://github.com/G6EJD/ESP32-OTA-Example


支援32GB SD Card, 可調整觸發距離, 可連網之危害告知器 - v2


Revision History: 
- v1 @ 2020/3/24: 第一版


本裝置透過超音波偵測環境中之物體, 當物體與本裝置間之距離小於預設值時將觸發本裝置之告警功能. 本裝置之觸發距離可以30公分為單位進行調整, 最遠可達300公分.


1. 透過內建 / 外接喇叭播放預先存放在SD Card (註1) 中之音聲訊息;
2. 透過外接之警示燈 (透過乾接點) 提供視覺訊息.
3. 透過網際網路對個人或群組發出E-Mail / Telegram等圖文訊息 (註2).

與使用紅外線感應之裝置相比, 由於超音波具有防強光 (太陽), 指向性, 波束窄, 及可測量與物體間距離之特性, 因此, 本裝置將可比使用紅外線感應之裝置更有效的防止誤動作之發生.

註1: 本裝置支持最大容量為32GB之Micro SD Card, 您需事先錄製欲播放之語音並將其存放在SD Card上後插入本裝置中. 若您需要能夠於現場立即錄音, 立即播放的版本, 請點擊下方網址.

註2: 需有網際網路連線並向本公司換購相對應之軟體.


ESP8266 - How to embed bootstrap in the SPIFFS disk of ESP8266

This is a quick write up of me following the instruction at the link below to try out embedding bootstrap in the SPIFFS disk of ESP8266.

Embed bootstrap into an ESP8266 Web server with SPIFFS