Building a current / flux probe for contactless measurements

In the last weeks I followed an idea to measure current without the need to cut the wires or even open a pcb trace. The solution i came up with is a hall effect based measurement.

I wrote some more about it in an article here:

If you do not like to open the full arcitle here you can review the basic schematic as well as to see a foto of my first prototype:

schematic of the prototype
Foto of my prototype

The first but still impressing measurement:

flux probe measurement at 10Hz
flux probe measurement at 10Hz, 10ms/div, red: output of probe at 200mV/div, yellow current at 33,3mA/div

Self driving car – Take 1

The following video shows the first quasi autonomous movements of my 1:8 sized buggy. I wrote a little script that makes movements suitable for turning the car.  I had no space in my flat for letting it run right now so I stuck with the ‘dry run’ for now. After adding some more sensors I will replace the script to be event driven instead of timer based.

The electronic components are: Toradex Colibri T20 on an Iris carier board running Linux (I got that one at embedded world this year) and an Arduino for controlling the servos. There also is a DC motor controller for driving the wheels that came with the car.

Finishing the construction of my 3D Printer

Over the weekend I finished the mechanical work on my 3d printer. It now has all parts assembled. It took a long time because the seller needed two more tries to deliver all missing parts. But finally I got all parts plus a few bonus parts. Thanks for that to John from!

As in my last post I have shot timelapse videos to show you the progress:

I connected all the motors, the heater and the thermosensor to the printer. Surprisingly all the axes were working instandly. Unfortunately the heater and the sensor were not working at all and the stepsize of the motors seem not to fit. Als I have to attach the end stop sensors to the printer for the Gen6 hardware… This means it will take some more time until I finally can print 😉

day 3 of embedded world


The final day of the exhibition “embedded world” was a bit less exhausting. We spend some time speaking to the people of the stand linux meets industry. This organisation is supporting big companies running and developing open source software as well as spreading the open source thinking.

The rest of my day was quite relaxed… we walked around a bit and talked to several companies as well as some people who were interested in the project leobots.

All in all the exhibition was a big success for the team as well as for me. We all got some great impressions what the embedded industry is like at the moment.

day 0 of embedded world

Today I travelled to Nuremberg with the other participants of our exhibition stand. We arrived really early about 4pm and equipped our stand for the tomorrow starting show.

Afterwards I went to my hostel room. I took a bed at A&O Hostel in the city center of nuremberg. It is next to the main station. As far as I can judge until now it is great.

After unpacking my stuff into the tiny locker in the room, I went to buy some food. On the way to the supermarket I came along a shop that was selling used stuff. I noticed a tripod in the shop windows. They sold a really nice looking one for only 29€, so it had to buy it at this bargain 😉 Just a picture with my crappy mobile phone cam:

my new tripod

When I came back to the Hostel I tried to connect to the internet. Seems that simyo delays the booking of the umts flatrates by some hours, so that I started whatching a movie. Some minutes later a roommate arrived – he came directly from india. He is going to visit the same exhibition, so we talked a while until we decided to go to a bar and have a beer and talk about the different cultures…

Some random updates

Some of you might know it already: I stop to participate at the students project Leobots at my university. There were some disagreements in the team over the last weeks that led to my decision to leave the team as of now. I just finish the documentation of my work as far as I got and support the team at the trade fair “embedded world” next week.

As I still like to play around with robotics I bought a small rc car, a wifi-router and some electronics. I hope to get it somehow self driving and self navigating in unknown terrain.

RC Buggy

I think my other new toy, the 3d printer will be a good help for my modifications… at least for adding backets for the distance sensor that is scanning the sourrounding of the car it will be superb to have a costum made part that really fits my needs 😉