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:]. 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.

Klackerlaken – Electronic Cockroaches for Kids

I’ve just finished a YouTube video about a small electronic project I’ve made this weekend with my kids: Electronic Cockroaches, or Klackerlaken, as they are called in German. We were inspired by a workshop for kids that took place a few years ago on the Chaos Communication Camp.

These Vibrobots are rather simple to build, but see for yourself:

All you need is vibration motor, a coin cell, a crown cap, LEDs or other decoration and Scotch tape.

My kids love them… 🙂

Thinkpad X200s: Sudden appearance of Intel AMT BIOS Messages

Had a strange effect on my Thinkpad lately – since a few days Intel AMT BIOS messages appear occasionally during boot-up:

Intel(R) Management Engine BIOS Extension v4.0.4.0007
Copyright(C) 2003-09 Intel Corporation.  All Rights Reserved.

Intel(R) ME Firmware version
Intel(R) AMT enabled
Intel(R) AMT configuration in progress
Inventory Update

Field Replaceable Unit List:
    Intel(R) AMT Table Valid

Media List:
    Intel(R) AMT Table Valid

    Table Mismatch - Updating Intel(R) AMT [Complete]
    Setting New Table Fingerprint

I had Intel AMT deactivated before and I’m not using the fingerprint sensor. The AMT features seem to activate themselves occasionally in the BIOS so my best guess is that the CMOS battery is dying… Will replace it and see if the strange effect disappears.

Update: I’ve replaced the CMOS battery and so far have not experienced any AMT messages. (Well on the first boot there actually was one telling me that the SMBIOS table was rebuilt.)

Dad’s Weather Station is up and running…

This weekend we’ve installed my dad’s new weather station. What’s left is to convince him to connect the receiver to a Raspberry Pi for better data logging… 😉
Weather Station

We added a wire to stabilize the sender/solar cell. We still have to make some improvements: replace the plastic zip ties with proper clamps for example.

The device was bought at Conrad Electronic (#672861) but its available from various vendors under different names and brands. This was actually one of the reasons for buying this weather station – its wide availability already led to various “hacks” and the stations’ data format/protocol is known.

So now I’m thinking about buying a second receiver (in China) to have one next to the Computer and one in the living room. Does anyone know which ones are compatible? I’m a bit overwhelmed by the number of similar looking stations…

Ripped off JTAG header pads on my dev FritzBox [FAIL]

Ugh… this is so disappointing. I tried to solder a ribbon cable to the JTAG header of my “development” FritzBox 7270. Right during the process I accidentally bumped against the bare PCB. It fell off the table and the already soldered cables ripped off some of the pads. Here’s a photo after removing the remaining cables:

FritzBox Ripped-off JTAG pads

I’m unsure how to continue. I followed the traces but so far did not find adequate vias or pads to solder to. At the moment I’m trying to not brick the FritzBox and therefore do not need a JTAG connection… again…

Partly-homemade MVG Tram Model

My sons are big “MVG Trambahn” fans. MVG, or Münchener Verkehrsgesellschaft, is the transport corporation responsible for most of the public transport (subways, trams, buses) here in Munich.

My sons favorite vehicle is the tram and they always wished to have one to play with. Well, I tried to fulfill their wish but the MVG does not sell toys. At their Trambahn Museum collector’s items are being sold but they are far too fragile (and too expensive) to let my sons play with them.

I was lucky and after some searching found a light blue tram (Amazon link) as a basis. After removing all the pseudo-advertising stickers I used my vinyl cutting machine and a SVG version of the MVG logo to create a rather realistic looking tram. See for yourself…

MVG Tram Model

The models’ dimensions are about 46 x 6 x 10 cm (L x W x H). The color of the original trams is a bit darker and their logo is white instead of black. (I did not have white vinyl when modding the tram and my sons don’t care.) Also the newer tram models have more than three segments.

Found an old Amiga Floppy Disk: Doctor Fruit

Ah! Those memories… I just found an old Amiga floppy disk while cleaning up: Dr. Fruit

Dr Fruit Floppy DiskDr. Fruit aka Doctor Fruit (Hall of Light reference) was an arcade game from 1987 that had a lot of gameplay similarities to Digger and Boulder Dash.

Dr Fruit Title Screen

Dr Fruit Gameplay

I remember playing it a lot when I was a kid. Nice mazes, but inaccurate joystick control and one of the most annoying music loops I’ve encountered in my life.