Celebrating the 0th Sunday of Advent!

0th Sunday of AdventEverybody knows – and many of us celebrate – the four Sundays of Advent every year. The First Sunday of Advent is often recognized as the beginning of christmas season. And celebrating the Sundays of Advent often goes together with an advent wreath with the four candles on it. So far – so good.

But: What most people don’t know is the fact that there is another Sunday of Advent which is called the 0th Sunday of Advent. This is very unknown but also very logical. One week before the 2nd Sunday of Advent is the 1st Sunday of Advent. So here it is: The 0th Sunday of Advent is one week before the 1st Sunday of Advent! Surprisingly this is also completely unknown to e. g. computer scientists or nerds who know that their computers start counting by zero. Continue reading

How I watched the solar eclipse: low-cost and safe

eclipse_4My experience with the solar eclipse on March 20, 2015 began one day before: A primary school teacher told me that the parents had to sign a form freeing the scool from any responsibility if their children get hurt from watching the eclipse. Furthermore, the parents were made responsible to equip their children with appropriate eclipse glasses. Children who didn’t bring the signed forme were refused to watch the eclipse. So what i’m asking myself is: What do these children learn? Do they learn something about nature and how to deal with extraordinary events or do they grow up in a climate of fear and learn how to delegate any responsibility to somebody else? Btw. the german word Angst also exists in english… Continue reading

Building a hot wire foam cutter – mechanics

hot_wire_cutter_0A hot wire foam cutter is a very useful tool to cut any type of styrofoam boards (expanded or extruded polystyrene) into the shape you want. The goal of this project is to build a low-cost cutter mostly from parts I found in my workshop that is able to do precise and straight cuts. Vertical and also miter cuts should be possible. This is a real hardware-only-project: no arduino, no programming, just plain mechanics and electrics: A thin wire is held in place and heated by a current. Continue reading

A picture a day from my chestnut tree part II

chestnut_2To keep the posts readable and loading time comfy I divide the series into parts. This is part two of the pictures from the chestnut tree right before my window. Have a look at what is happening from day to day and enjoy what nature is doing! This project is a work-in-progress and new pictures are added on a daily basis. Note that the pictures are not processed with filters, colour changes, sharpening or anything else. I only scale them down to fit into this post.


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A picture a day from my chestnut tree

chestnutRight before my window lives a big chestnut tree. As it is springtime now the buds are bursting and everything is growing. I decided to take a picture of one of the buds every morning. These pictures show the fascinating process of the buds when they get open and leaves and flowers appear. This post is a work in process starting with the first picture on March, 30 (ok, there is no picture fom March, 31). All these pictures aren’t photoshopped in any way. I only shrink them in size.

Enjoy :-)

heliosoph Continue reading

Face tanner to PCB UV lamp

uv_lamp_displayThese times it seems like everybody does his PCBs at home and posts about his process. So do I. I bought me a used face tanner in order to use it as UV lamp for my PCBs. There is also nothing new to what many others did before. The face tanner also had a time switch that (I thought) would make it a perfect UV lamp without the need of modifications. But the time steps were too coarse. So I modified it to have a finer time control. This is what this post is about.

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512KB EEPROM for your ATmega328P

uptime_setup_512kb_eeprom_headerDuring my minimalistic solar powered datalogging project (here, here and here) I was at the point where I had more data than could be stored in my 32KB EEPROM. It was time to have more! As I already had the 24AA256 (32KB) from Microchip because of the wide supply voltage range and the low power consumption I looked for the biggest one of this series: The 24AA1025 is a 128KB EEPROM! It’s pins A0 and A1 can be used to address more than one chip. So there is a maximum of four chips giving you a total of 512KB EEPROM for your ATmega328P. This post describes the hardware setup (easy) and the software side. In the end we have a 512KB EEPROM memory with linear address range. Continue reading

Arduino powered by a capacitor – towards a real system

atmega_capacitors_pv_8Now that we walked through all the steps of reducing power consumption from the start through first tests, reducing consumption, optimized tests and adding a RTC including the problems of waking up from sleep via interrupt, adding a 24AA256 EEPROM as external memory. and using it in page mode it’s time to make a more useable system from what we have.

The first steps are increasing the datalogging interval and then using a supercapacitor.

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TimerOneThree library for ATmega1284P

atmega1284pThe arduino TimerOne library described at http://playground.arduino.cc/Code/Timer1 is the starting point for this lib. In the original library that can be found at http://code.google.com/p/arduino-timerone/downloads/list the pwm pins are (sort of) hard-coded to fit to the ATmega168P / 328P (the chip of the Uno R3 board). I simply changed them to the pin settings of the ATmega1284P using maniacbug’s pinout. Then I doubled the code and adapted it to timer3 of the ATmega1284P and it’s pins. Continue reading

Arduino powered by a capacitor – EEPROM in page mode

atmega_capacitors_pv_7This is the next step forward In my “minimalistic standalone ATmega328 powered by a capacitor”. In this project I was walking from the start through first tests, reducing consumption, optimized tests and adding a RTC including the problems of waking up from sleep via interrupt. Then I added a 24AA256 EEPROM as external memory. EEPROMs are good for data storage as they keep data even when supply voltage has gone down. But they are slow, especially in write mode. This means that a lot of time is spent by simply writing two bytes of data into this memory and thus, energy is consumed during this time. Now with the 24AA256 it is possible to write up to 64 bytes at once. This is called “block mode”. Let’s look if we can reduce energy consumption furthermore by using this feature. Continue reading