driving a vacuum fluorescent display:
The vacuum fluorescent display I salvaged from a Samsung SER6540II was only waiting to get used. This was the ideal opportunity to learn how these retro style displays work (through Supertex HV518 drivers) and get familiar with a new micro-controller (ARM Cortex-M3 based STM32F103).
my custom wireless electricity meter:
While renewing my distribution board the land lord decided to remove the electricity meter. Now I can't note how much electricity I am using. So I decided to build and install my own electricity meter: the spark counter.
Using a cheap power meter (i.e. peacefair PZEM-004), a microcontroller (i.e. Arduino Nano 3.0), radio transceivers (i.e. nordic nRF24L01+), a single board computer (i.e. Raspberry Pi), and some storage and visualization tools (i.e. influxDB and grafana) I am now able to measure, log, and monitor my electricity consumption.
creating an open source hardware logo:
What better than a logo on your hardware to show ir is open source?
Such a logo provided by the Open Source Hardware Association even already exists, but the rights on it were not clear, no vector version and footprint were provided, and it's quite hard to draw in electronic CAD softwares.
So I decided to create my own open source hardware logo for my electronic designs.
It's simple and can be drawn easily in any CAD software, but the generator already lets you customize it and export it as vector graphic or as footprint for your electronic CAD software.
building an ambient light for the screen:
The CuVoodoo ScreenLight mimics the Philips ambient lighting. The idea is to have LEDs on the back of the screen, lighting on the sides the same color as the border on the screen, creating an ambient light.
To implement this I used: VLC (with the AtmoLight video filter) or boblight (way better) to output over serial the colors to be shown on the LEDs; an Atmel ATmega328P microcontroller at 16 MHz (i.e. Arduino Nano 3.0) to control the LEDs and show the values received over serial; a strips of WS2812B chained LEDs (i.e. BlinkyTape), individually controlled using a data line.
testing the accuracy of a power supply:
It was time to get a decent power supply, and so I found the EA-PS 2084-03B. It fulfilled all my criteria: good quality, silent, wide voltage range, and most importantly with PC connectivity.
But somehow the reading on the LCD does not match what is output. So I implemented a program to remotely control and monitor this power supply, and with a PC connected UT61E multimeter I can compare what is set to what is output. This way I can measure the power supply's accuracy.
reversing washing machine payment cards:
To use the washing machines in my apartment complex you need to pay using a rechargeable contact card.
I was curious to find out how it works. It turns out it's an I²C EEPROM in a card.
By recording the communication between the card and the machine I figured out where and how the credit value is stored.
Now I can read and write the value on cards using a Raspberry Pi or simple micro-controller, but also program my own cards to work with the machines.
building an electronic cat repeller to guard the fridge:
My sneaky cat can open all doors, even the fridge door. No meat is safe any more.
To prevent that I built a cat repeller using an Atmel ATmega328P Arduino Nano 3.0 board.
An HC-SR501 PIR motion detector checks if the cat is nearby. Then an E18-D80NK range detector verifies if the cat is in front of the fridge.
If this is the case a ~24 kHz PWM signal will generate an ultrasound using a piezoelectric diaphragm, encouraging the cat to leave the premisses.
If it still opens the fridge, a human audible alarm will sound until it is closed.