Fail: a Ball Bearing as Sliding Contact

Saturday, May 12th, 2012

Coming closer to the point where the electronics for [Diskokugel] are settled, I start worrying about how to get sound and power into the turning thing. While with the sound I’ll most probably go for a wireless solution, with the power that’s highly unlikely. So I did an experiment with some ball bearings I had aquired for the (still pending) [cnc project]. I soldered wires to the in- and outside of the bearings to power a turning 1W LED. That resembled the setup I would have liked to use building a second [LED lamp]. Unfortunately even with a 1000µF capacitor on the LED end it wasn’t possible to keep the power straight. It might be helpfull to get the plastic caps of the bearings and apply a certain pressure on one side to keep the contact constant, but in general I abandoned the idea for high power connections. Considering the fact that the Diskokugel might use up to 200W at 5V there seems no way to keep the supply steady this way…

2 ball bearings on an axis as sliding contact

Diskokugel News

Thursday, May 10th, 2012

As promised, Christian and I went to testing the new Diskokugel board last weekend. We started by soldering one of the LM4863s he bought on eBay to the new board. Christian had his concerns whether the stuff he bought from Hongkong would actually work :) During the last week I finished soldering most of the parts to board (my first smd project!).

Next week I will test the board as a whole to determine whether the actual delay of 6 months was worth it. If it turns out that the new design doesn’t meet my requirements I will simply go back to the old design and continue there. Progress needs to be made!

testing the lm4863

my first smd board!

Its been a long time

Friday, May 4th, 2012

I should apologize for my long blogging abstinence, especially since no blogging usually means all the more has happened.

I was extremely busy with my new job at KOMA, learning a lot at the same time. I tried to attend an online electronics engineering class of MIT at the same time, but I had to let that go because my time didn’t suffice to make up for all the math I would have had to relearn to understand what they were talking about.

Meanwhile I continued to work on the new Diskokugel board. Christian sent me a schematic using a BT4863 as amplifier. The ones he got are a smd chips, so I redesigned the whole board for the use of smd parts. I sent the result to Christian and maybe we get to test it this weekend.

It was my first project using Kicad instead of EAGLE for circuit board design. We use Kicad at work and I actually found it better to use than EAGLE, even though I had to run it on a virtual Linux because I was to lazy to compile the latest source for Mac.

On other news: the CNC project is delayed until further notice due to missing resources (meaning time and motivation). My work at KOMA inspired me to do more with music again, which led to the idea to build a dub delay and a modular OSC controller. Let’s see what happens there. Actually, I wish these new ideas would stop so I get to finish some of the stuff done that I came up with in the past…

Happy NEW YEAR!!!!!

Sunday, January 1st, 2012

Greetings from Thailand! Live long and prosper!

New Year

And what did you do today?

CNC me pt. 3 – creating realities

Saturday, December 3rd, 2011

Having at least a plan for the cross table I started working on the parts. I struggled for a while trying to find a place with the means of doing precise cuts and drills into aluminum. In the end I did the cutting in a former workplace of mine and had to do the drilling at [c-base] of which I am a member for about a year now. There I had to cope with a cheap drilling stand. I built me an improvised guide to at least have some precision in one axis. Some holes I had to turn into long holes to be able to adjust to tolerances. Those don’t look so good but I hope it will do.

I found some basic flaws in my design already. I made the mistake of not taking sideway pressure from the drill itself into account. The telescope slides have a sideway tolerance of about 1mm. I will continue anyway, maybe I find a way to correct this by adding guides or the machine will at least give me the means of drilling exact holes and help me build the next one ;)

the drilling guide

a long hole. a crater, rather

21st of december: all parts drilled

CNC me pt. 2 – Electronics I

Saturday, November 19th, 2011

Searching for a control solution for my CNC mill I found a whole bunch of possibilities. My requirements were these:

  • cheap (why, of course!)
  • USB solution
  • ready PCBs
  • open source if possible

Most CNC configurations still rely on a computers LPT port. This is due to the fact that a program can access this port in realtime as opposed to the USB port, which is buffered. There are several solutions on the web using microcontrollers to execute the code given through the USB port. I went for the one done by [planet cnc] in combination with classic l297/298 motor drivers by [PMinMO]. Both provide ready to use parts, kits and schematics to do your own board designs. I went for the kit solution instead of designing my own boards because I wanted to spend more time on mechanical design. PMinMO provides a truly great documentation with his boards, by the way! I got a PCB and a preconfigured chip from planet cnc. He provides a software with drivers for windows (costs though) that should also work under Parallels and such.

I soldered one driver and the controller board together but haven’t gotten around to do any tests yet…

soldering the smd parts to the driver board

the controller (w/o chip) and one driver, waiting to be tested

CNC me pt.1

Friday, November 18th, 2011

I started making plans for a CNC mill some weeks ago and totally got sucked into it. Here are some pictures of the plans i made with sketchup. More soon…

the bottom axis

the second axis

Update 11/11

Saturday, November 12th, 2011

It’s been a while since my last post, so i think you deserve a little update on my where- and whatabouts.

After spending most of the summer doing technical coordination for the [Festival Über Lebenskunst] I went directly to helping the team of Tomas Saraceno set up his exhibition at [Hamburger Bahnhof], Berlin. I really enjoyed that, Tomas having a nice team and his works keep impressing and inspiring me.

Right now, badly in need of a job to earn as much as I can before going to Thailand in January, I started a soldering job at [Koma Elektronik], helping them to assemble their circuit boards .

Of course, I kept working on the [Diskokugel], trying to improve the circuit. Read more about that [here]. I also contemplated some on my actual intentions with this object. I will share that with you soon.

And, to make things worse, I got inspired by an [instructable] to build my own CNC-mill. That is just another example of how I constantly underestimate the time and effort (and money) of the tasks I keep imposing on me. I’ve already invested 3 weeks into it without any visible result and I keep going… Il post some pictures soon, however.

On other news: Halloween came and after laughing my ass off watching this [cookie monster video] repeatedly, I had to refer to it with my costume for the annual party in Frankfurt.

God's away on bizniz...


Trying to make Diskokugel louder

Tuesday, November 1st, 2011

After my first experiences with the [Diskokugel] circuit building [Audioweb] and [AudioSphere] I tried to optimize the circuit for further use. That means I tried to look for a way to get some head room with the volume, since the current design didn’t quite satisfy me volumewise. I discussed the problem with Christian and we did some experiments using a [TDA7053a]. Not only would the TDA make a higher amplification available. Working on 5V instead of +/- 5v, as the transistor circuit works right now, it would have rid us of one power line that has to be transferred into the turning ball via a sliding contact. Also, soldering two chips on the board would have been much faster than soldering those 16 transistors.

The TDA7053 has a DC volume control input, which made us hope that we would simply connect it directly to the 4094 register to switch it on and off, making the 4066 switch obsolete. Unfortunately that didn’t work. The 7053’s offset voltage rises with the applied control voltage, thus producing a crack at the output when raised rapidly. Ultimately we got the thing working by keeping the control voltage at ~0.7V and switching the audio signal on and off with the 4066. However, since in this version all amps are constantly active, I am afraid the whole system would be prone to interferences and the power consumption would be very high. I had a very hard time testing the whole setup. I don’t know if it was my breadboard or whatever, but something started oscillating regularly and there was never a setup tat was save from that or other interferences. Christian told me however that he got something working.

I am not sure how to proceed yet. I think I will stay with the old circuit for now and see how far it takes me. After all, one result of the experiments with the TDA was that a higher volume makes it harder to locate the source of the signal. That would be sort of counter productive. It also shows that there are possibly limits to the use of this whole technique…

Audioweb 0.1

Monday, September 5th, 2011

As a special gimmick for my birthday party i used the elements of [Audiosphere] to build a web o 6×6 speakers on a wall in my room. The sensation is, of course, a different one and since its now totally at hand, I will do some more experimenting in the next weeks.


the cable length of the sphere didn't fit, so it doesn't look perfect yet. I still like it :)