Webserver down alarm on Tessel board

If you are running website on a server you know that many things can happen. It can go down due several reasons and you may notice this only when try to connect or load webpage. In order to avoid long downtimes you need to set up alarm which would ring bells and whistles once it goes down. Kelsey shared a website down alarm project based on Tessel board.


Tessel board simply pings website every second and once trouble is detected it starts alarm which is a large red alarm light. Lamp was modified to be controlled from relay module which plugs directly to Tessel board. Speaking of Tessel boar it is an ARM processor based development board which runs entirely on Node.js. It already has built in WiFi module what makes it great tool for Internet of Things (IoT).

DIY smart tweezers that measure RLC and impedance

Regular multimeter isn’t convenient to measure parameters of SMD components. Also most of multimeters measure only R and C, but not L and Z(impedance). For SMD components you need tweezers that can reach small contacts. If your budget is limited and you want ZRLC measurement features, then probably go with DIY version. Ajoyraman shared his instructable, where he builds tweezers around TMS320F28027 microcontroller. To switch between modes he uses ADG714 analog switch and rail to rail operation amplifier MCP6022.


To make tweezers small and yet functional, he is not using any displays on them. Instead he connected tweezers to PC via USB where information is seen in nice PC GUI. You can find all codes in GitHub. We have seen how resistance and capacitance and inductance can be measured. More interesting feature in tweezers is impedance measurement. The idea is to generate sine wave and pass it through unknown impedance. By measuring amplitude and phase on target PC software is able to process and display real and imaginary part of unknown impedance. PC software is very well built with complete information for each measurement mode along with graphical representation. It could be great tool on your desk that would cost you no more than $25.

How to interface eC probes to any microcontroller

eC stands for electrical conductivity. So eC probes are normally used to measure conductivity in a solution like hydroponics, soil and water. Measured date allows to determine amount of nutrients and salts. But you can think of many more uses where electrical conductive measurements would give a clue whats going on.


Interfacing eC meter requires some analog conditioning before data can be read by microcontroller. Sparkyswidget have built an interface module that can be used with any micro that has I2C interface. Popular ones like Arduino or Raspberry pi have no problem with that. The module itself packs few important parts that enable reading data from probe. First of all there is a Wein Bridge oscillator that creates low distortion sine wave. Signal then is scaled down to 0.2VPP gain amplifier that treats probe as unknown resistor. Then signal passes through diode rectifier. All this part is assembled around single quad op amp. Rectified signal reaches I2C ADC which can be read by micro.

Vacuum Fluorescent Display Alarm Clock

This is a special type of Alarm clock which is built around a vacuum fluorescent display. Along with the alarm clock, it also shows unread mail as well as the weather of the city. Overall it’s an exciting Internet of Things Based application. The author has written a driver for the display in C# that will make things easier if you are trying to yourself. The processor is from the Renesas R8C lineup which I looks new to me.


The existing code for the application have been uploaded to Github so that more features can be added in the near future. The concept looks easier to understand from the pseudo code provided. The code might be a little messy but it works flawlessly. In the initial run, it takes time to capture data from the mail client and open weather but that only a one time process. All the codes along with the LCD driver and necessary hardware can be obtained from the project website.