RANT: Do not misuse spreadsheets for data storage

Using spreadsheet files for data storage and exchange can lead to the
corruption and even loss of information — sometimes without noticing it immediately. I came across this one too often so I could not help but write a rather long post about this topic.

Sharing datasets with other researchers or collaboration partners is a vital part of the knowledge exchange in a community. This might happen in big scale in form of supplementary material along with publications or in small scale within research groups. In this post I do not want to focus on what is actually shared, but how. Because a crucial but commonly underestimated element when sharing datasets with others is the used data format. Continue reading “RANT: Do not misuse spreadsheets for data storage”

I made it: I switched from Eagle to KiCad to make my PCB designs…

Half a year ago I’ve started to use KiCad for new PCB designs I’m working on. I already wanted to try out KiCad for quite some time. Its release 4.0 and the latest changes in EagleCAD (annoying ads and recently being bought by Autodesk) were enough pressure to switch. And what should I say: after dealing with the rather unhandy library management and some cryptic error messages I really now enjoy KiCads workflow.

This post is about my experience with the transition to KiCad as my new PCB designer. It is based on the newest version 4.0 of KiCad and its daily builds via the respective Ubuntu PPAs. Continue reading “I made it: I switched from Eagle to KiCad to make my PCB designs…”

Dumpster Dive / Teardown: Moser Galvanosan Feinstromgerät / Galvanic Stimulator

From time to time I have (and take) the chance to dumpster dive for electronic parts. Recently, on one of these occasions, an old piece of hardware felt into my hands: a “Moser Galvanosan” galvanic stimulator.

To be honest, I’ve had no idea what it was and at first I only thought it would be a nice case for another project I was working on. After some research (out of curiosity) I thought the device is interesting enough to take some photos of its interior and write about it.

Disclaimer: I’m totally not into alternative medicine or stimulation current therapy. I’m just taking an interesting looking piece of hardware apart, that’s all!

Continue reading “Dumpster Dive / Teardown: Moser Galvanosan Feinstromgerät / Galvanic Stimulator”

Review: Addifix 9 Mechanical Number Cruncher and Pocket Calculator

While trying to explain the meaning of the carry digit during addition an subtraction to my oldest son, I’ve given him a nice little device to play with: the Addifix-9 number cruncher.

I’ve briefly mentioned this device before in a post. This time I’ve made a short video about the mechanical calculator in action and present more details:

In the 1950s/60s The Addifix series was sold as “Addifix-9 Taschenrechenmaschine” by the German mail-order company Neckermann. Its predecessor was the Addiator from Carl Kübler which was sold since the early 1920s  [Source: sliderulemuseum.com]. The underlying mechanical principle is quite old (an documented example is the mechanical calculator by Claude Perrault from the 17th century).

The Addifix is a pocket-sized (13 x 9 cm) slide adder that can be used from both sides – one side for addition and one for subtraction. The slides (one for each digit) are handled with a metal stylus.

USB Voltage and Current Meter [Review]

I recently bought a few powerbanks to replace by self-made battery-packs and to have an “emergency” power supply for my iPad. (I always forget to charge my iPad during the day and get angry about myself in the evening.)

To test the power consumption on my devices (without always hanging a volt meter in series to my devices) I’ve bought a USB voltage and current meter. The device is simple to use – just stick it in between the device you want to test and your computer/ charger/ powerbank. Its OLED display shows the voltage, current, power, and capacity (nice, but why?) of the attached device.   Continue reading “USB Voltage and Current Meter [Review]”

Mega328 (Transistor Diode Triode Capacitance ESR) Tester [Review]

A few weeks ago I read a post (on Hackaday) about a quite versatile component tester and considering its low price I yielded to the temptation to buy one on eBay

Well, it arrived this week and so far I’m quite impressed how flexible it is in identifying various components (capacitors, diodes, transistors) I’ve stuck into it. It is surprisingly accurate as far as I can compare it to my multimeter (which on the other hand is pretty cheap).Mega328 Tester TransistorOne of the reasons of buying it is my hope to keep its firmware up-to-date due to the pretty active community on microcontroller.net — see this mostly German thread) on its development. It is built around an Atmel ATMega328. Continue reading “Mega328 (Transistor Diode Triode Capacitance ESR) Tester [Review]”

Osram LED lamp [FAIL]

About two years ago we started switching from compact fluorescent lamps to LED lamps, mainly to avoid the mercury in the former ones. Also the longer lifespan of LEDs was a reason for us to switch. We currently have two types in our household: several cheap ones from Müller Licht (ALDI) and a bit more expensive ones from OSRAM. Guess which ones failed first…

Defective OSRAM Led LampThe stated 100,000 on/off cycles or 25,000 hours of run-time (at least that’s what I remember from their package) were definitely not reached. Far from it.

OSRAM gives a 4-year guarantee as far as I understood from reading their website. But to be honest: who keeps a bill for a lamp bought with other purchases two years ago? At least I did not… Sigh. 🙁

Raspberry Pi Power Supply: Nokia AC-10 + AC-16 [Review]

The Raspberry Pi is shipped without a power supply — there is not even one specifically available for this board as far as I know. Any micro USB power supply with a least 700 mA should work. But I did not want to rely on no-name products since the board should run continuously and the web is full of reports of counterfeits. So I’m currently using a Nokia AC-16E power supply, bought directly from Amazon (not on the Marketplace). Additionally, I bought a Nokia AC-10E (more or less for free, as their combination allowed free shipping). Based on the way the two Nokia supplies were packed and labelled (including safety marks and QR-Codes) I believe they should be genuine.

From left to right: OTB TR-005, Nokia AC-10E, Nokia AC-16E.

I tested the Nokia supplies and another (cheap/crappy?) one from OTB I already had lying around. Update: As requested in a comment, I have also added measurements of the on-board voltage between TP1 and TP2 (more information about these pins can be found here).

Power Supply Price (ca.) Output Voltage On-board Voltage
On-board Voltage
(attached devices)
OTB TR-005 3.- € 5 V / 1,000 mA 4.90 V 4.78 V
Nokia AC-10E 7.- € 5 V / 1,200 mA 4.88 V 4.82 V
Nokia AC-16E 13.- € 5 V / 1,000 mA 4.75 V 4.66 V

All three of them were able to support the Raspberry Pi board with several connected USB devices (passive hub, keyboard, mouse, wireless adapter) and a connected monitor (HDMI). There wasn’t much difference between them, all three ‘consumed’ about 3.8 W (6.7 VA) on average (1 hour; varying workload) and I did not notice any glitches. Still, a power drop was noticable when comparing the on-board voltage with and without any attached devices (sd-card only).

With the Nokia AC-16E power supply, the voltage dropped below the recommended 4.75 V.

In conclusion: I think I will stick to the Nokia AC-16E, as I’m currently running my Raspberry Pi only with an attached wireless usb adapter. If I notice any glitches, I can still switch over to the Nokia AC-10E power supply. Something that looks beautiful is not necessarily always better… *sigh*

Update [2014-11]: I’ve in the mean time switched to the Nokia AC-10E supply which seems to be more stable. Also I am running a second Raspberry Pi B+ now with a 2 A power supply.