Archive for August, 2008

Acer XD 1150D

Friday, August 22nd, 2008

So you might have read about it already but to say it once again: i wrecked my diy-projector. totally my fault. nothing to repair.

so i spent some time searching for an alternative and looked for a new display. But since they are about 50Eur i figured, why not look for a used old cheap real projector with some hour on it.

So my research brought up a model from Acer called XD1150. A very good site with details, calculators, comments and links to new bulbs is Just enter ‘acer 1150’ where it says ‘Projektor Modell Suche’ and the model will show up with its specs.

The basic details are:

– Native resolution: 800×600, up to 1280 x 1024 interpolated

– 180W SHP bulp with 2000h lifetime

– 1 DLP Chip

– VGA in

Since im not the high-end HD moviewatcher anyway i had some different requirements for my future center of entertainment:

– please be littler then my overheadprojector

– not as loud

– vga in

– cheap usage

– resolution and the technique were not a priority criteria.

The XD1150 seemed to fit all of those so i looked around, and found a used model with 450h on the lamp (so theoretically another 1550h left) on ebay for 230Eur incl. shipping. At you pay about 250Eur to 280Eur for an 1150 and about 310Eur for an 1160, which is basically the same model with more inputs and batterysafing-mode (3000h on a single bulp). A friend of mine tried the XD1160 and is very happy (after 150h of bulptime). New bulps can be purchased for example here: for about 140Eur.

So lets let the numbers talk: the projector is 250Eur and will last (pessimistically) 1500h. It consumes about 230W while running which adds another 345kWh to the equation. Lets say the kWh is at about 20ct (again, pessimistically, see wikipedia) so the powerconsumptions costs 69Eur. That added up with the initial cost shows us that the hour runtime costs about 21ct, a reasonable price for your own homecinema! Just imagine you watch 3h (like 2 movies) a day, thats still 500 days or 1.37 years. And once your bulp broke down, i think LED-projectors are strong and affordable. At least thats my hope. Or i go another 1500h with a new bulp.

The powerconsumption was measured with one of those plug-in-between-units, while powering off, the projector only eats 6W for the fan. The powercable is a default cable used with computers.

The projector comes with a variety of settings like brightness, colourthemes, anti-trapezoid, etc. Also there seems to exist an infrared remotecontrol, which was missing with mine. If you want, you can also use the projector in back-projection mode or mounted up-side-down on the ceiling.

Mounting was pretty easy for me, since i built a holder out of wood and screwed it to the wall. I think the projector has some standard-mount-holes so you can attach it to any holder that fits.

One word on the so called rainbow-effect (RBE, see that can be noticed with 1-chip DLP projectors. Since the chip can not show all three colors at the same time (red, green, blue that is, newer 3-chip models can), it needs to throw the colors one after the other on the wall. If you move your head quickly during a scene with lots of movement (or move your hand quickly in front of your eyes), you might see the colors of a rainbow, but i normally dont notice anything and am therefore a very happy home-cinema consumer.

summing things up, i found a cheap way of throwing movies at my wall and im so happy with this product that i can just recommend buying one, if you are on the hunt for a projector and have the same requirements.

Comming soon: distance and diagonal of image, projector in action.

LED Taillight for bikes with a dynamo

Wednesday, August 20th, 2008

Observing the strong growth of usage of Light Emitting Diodes for lighting purposes of every kind, tinkering with LEDs has become a well-loved topic to me. So, after the little bulb of my bike’s taillight has died, it was obvious not to simply buy a new one, rather to upgrade the good old “Busch & Müller Toplight” to LED technology.

First, I want to explain the “phenomenon” of dying taillight bulbs. A dynamo is considered to be a current source. Now, if the headlight bulb dies, or its connection to the circuit is interrupted (like it was in my case, a loose connection), the load of the current source is being increased because head- and taillight are connected parallely to the dynamo. After Ohm’s law, this causes an increase of the supply voltage. The taillight bulb can’t get along with this higher voltage long time…and dies. Same thing the other way round, but headlight bulbs are usually more resistant against higher supply voltages.

Keeping this hazard in mind, i wanted to build in some overvoltage protection into my new taillight – LEDs have become cheap, but I’m not made of money ;-)

My dynamo -a FER 2002- provides 3 W at 6 V (like the most ones on the market). The headlight consumes 2.4 W, so the taillight may consume 0.6 W.
After some research in the www, using four ultrabright LEDs seemed to be enough for my purposes, moreover I don’t want to dazzle other road users. Fortunately I had four pieces of ultrabright white LEDs at home.
Now just take a look at the schematic.
Note: It’s just a proposal from me, it’s cheap, quickly built and works. If you have other ideas or improvements, please let me know!

LED Taillight Schematic

LED Taillight Schematic

Bill of Materials:
D1…D4 Ultrabright white LEDs, 3.2 V, 20 mA, 15500 mcd (but I recommend red ones, see below)
D5…D7 1N4001 – Standard Diode
D8,D9 ZY6,2 – 6.2 V Zener Diode, 2 W (!)
R1 68 Ohm, 0.25 W Resistor
R2 15 Ohm, 0.25 W Resistor
BR1 B80C1500R – Bridge Rectifier
C1 optional Goldcap Capacitor

Explanation of the Schematic:
The bridge rectifier simply makes DC voltage out of the AC voltage provided by the dynamo.
R1 is the required series resistor for D1 and D2 (I think showing the calculation is not necessary at this point).
With D5, D6 and D7 I’m scaling down the voltage for the other two LEDs, so a smaller series resistor is required. Why so pedestrian? Because I wanted to prepare my light for equipping it with a goldcap capacitor, so D3 and D4 should shine while standing at traffic lights for example. A goldcap has a maximum voltage of 5.5 V (first reason for the diodes). And with a higher series resistor there would be a higher power dissipation at this point – and I want to use the small budget of power stored in the capacitor as effectively as possible (second reason). Unfortunately, I didn’t have such a capacitor at hand, so I left it out for now.
According to my calculations, a 0.47 F capacitor should light up the two LEDs for about 20 seconds.
Last but not least, I wanted to build in an overvoltage protection. First idea was simply to use a Zener diode, but I kept in mind that in the case of a fault, a current of 400 mA would rush through the diode. Using a 6.2 V Zener diode, there would be a power loss of 2.48 W. Normal Zener diodes can handle power up to 0.5 W, so I looked for some high power Zener diodes. The 5 W ones were pretty expensive and not available, so I just took two pieces with 2 W and built them in parallel.
And voilà…that’s it!

First, open the Toplight and trim a piece of hole matrix board so it fits into the quadratic opening (see picture). Then just solder the components onto the board, but take care – the LEDs shall fit through the hole where the bulb is put through normally. (Hint: leave the pins of the LEDs as long as possible)
Be sure you really want to use your LED light from now on instead of simply buy a new bulb, because the next step is pretty destructive. :-)
You have to cut off the black plastic holding for the bulb, until the two pieces of the Toplight fit again and you can reassemble it. Don’t forget to attach wires from your board to the connection terminals of the light!

Overview of the assembly steps

Overview of the assembly steps

Now you can install your new dynamo powered LED taillight on your bike!

Additional information:

  • I strongly recommend the usage of red LEDs instead of white ones. In my case the white ones are too bright, even for the red plastic, and so it’s more a purple taillight than a red one. So use red ones, and you will have a red taillight.
  • Why use such an outdated thing like a dynamo? There are cheap and good battery powered bike lights on the market! Well, a dynamo never runs out of power, is more reliable and you can’t forget it at home!
  • If you want further information about building LED bike lights or the usage of LEDs generally (and you understand the german language), check this website: LED Treiber

So I hope you enjoy the building and the use of this simple but cheap taillight! Sure, there are many more good plans for LED lights in the www (see LED Treiber), but hey..SIMPLE…CHEAP!
If my headlight (a B&M Lumotec Halogen) dies one day, I will turn it into an LED light also, be sure to find an blog post about it here.

Very important notice:
The usage of self-built lights in road traffic are not allowed in every country. Use at own risk!

Take care & have fun!

[PHP] Small usercounter

Tuesday, August 19th, 2008

So there was a contest (over at on quakenet) to write a small PHP-Counter with graphical output, my contribution:

if(($fgets(fopen($f,$m)))<$t-$p){fputs(fopen($f,’w’),$t); touch($f*$t);}}ImageString($o=ImageCreateTrueColor(99,9),1,2,1,(count(glob(‘*’))-1),65535);

May I introduce myself…

Tuesday, August 19th, 2008

Hi there, my name is Chris007, and I am a student of Electrotechnical Engineering here in Munich. In the past, BEni and me built up and managed several projects together, just like providing a photopage and a bulletin board for our friends/the youth community in our hometown and many many other programming and website stuff, another blog (but one of the _blathering_blogs), more picspage, more bulletin board, and so on. But most of it has gone offline long time ago, through lack of time and/or interest – yah, you understand me ;)

My intention is to support BEnis Blog from time to time, for keeping the blog alive in times the mastermind has to do other important things, and keeping u blogreaders well informed about the stuff we (try to) do.

Well, I hope you will find some interesting information in what I write, perhaps it helps you solving a problem you actually are confronted with – at least my posts may entertain you and prevent you from doing other stuff!

Turning an IBM Netvista 2200 (8363) into a server

Monday, August 18th, 2008

So i have been on the hunt for a tiny PC which i could turn into an always-on server for a while now. I played with an Compaq IA-1 (check out ia1-hacking and but since it lacks an ethernet device (and let me asure you, usb-ethernet is way slow, escpecially on usb1.1) it was kind of unhandy as a fileserver. The well known ‘slug’ (look for NSLU2) is another alternative but rather pricey.

Ive had my eye on some netclients (normally just networkcards with a graphicsadapter and you connect it to a powerfull mainframe) but never found one in my pricerange (less than 50 Eur). Then i came across the IBM Netvista 2200 (8363) which met the following requirements:

– PC compatible architecture with reasonable horsepower
– diskless operation (e.g. through compact flash)
– USB Ports
– small power consumption
– builtin fast ethernet (10/100mbit)
– stylish outfit since it will be placed on my workdesk

There are a couple of models (Netvista 2800, etc.) which have more power, a real pci-slot or more diskspace. But they are also more expensive so back to the 8363.

Some people get confused with the different series there are. You can identify the serie by looking at the serial number (surprise!). Some models end with -Exx (xx as a placeholder), other with -Wxx and again others with -Txx. All feature the same hardware more or less, but a short explanation:

-Exx: the _E_thernet model. It comes with an ethernetcard and the regular hardware

-Wxx: WindowsCE model. On this machine its possible to run WindowsCE. It features ethernet and i think a bigger internal storage disk

-Txx: Tokenring model. This model has a Tokenringcard plugged into the ibm-pci-slot IN ADDITION to the ethernetcard.

Thats an important fact since a lot of people on the internet think that the -Txx model only features Tokenring (which nobody uses anymore, read more about it here: wikipedia), which is not true. The tokenringcard is plugged in an pcislot that looks like it is some proprietary port from ibm. One screw and its removed and you have a good -Exx model. And most of the time the -Txx models are way cheaper (since nobody knows).

So i received my model and turned it on. It tried to boot via network. But it worked!

The netvista features an builtin CompactFlash-Slot from which it can even boot. So my plan: build a linuxkernel and a filesystem and put it on the CF-Card, boot the system, mount my external USB-Hdd, start a web and ssh server and provide some php scripts to the net. Let me tell you, after some tinkering it works great!

In order to boot from the CF-Card you need a BIOS that supports this feature. To enter the BIOS keep on hitting ESC or ENTER until it shows up. Check the version it should at least say:
If you have an older BIOS (which doesnt support booting from Flash) you need to update your BIOS. You can either boot the updatefile via net or put it on a CF-Card. I chose the later since i didnt want to setup a networkbootserver. You need a FAT or ext2 formatted CF-Card which contains the bflash.2200 file (name must be exactly this!). You can obtain the file directly from IBM or through the links mentioned here. When booting the machine, it detects the updatefile and asks you if you want to update. You want to. Dont turn of the machine now or disturb it until its all the way done.

Congrats, you can now select ‘Flash’ as a bootdevice in your BIOS. In principle the things are straight forward from now on. You need a file named kernel.2×00 in your rootdirectory (remember ext-filesystem!) which will be booted by the builtin bootloader.

A short word on 2.4 vs. 2.6: since IBM created the firmware for 2.2 and 2.4 kernels they are much easier to use.

But its also possible (and desireable) to use a 2.6 kernel. In order to do so, you need to patch the kernelbinary, patch the geode-video-driver source and remember to configure the kernel properly. this describes this process. You will find patches, kernelconfigs and instructions also here. Thanks to both i got my stuff running!

Im running a kernel with the kernelconfig attached below. Somehow building an initramfs into the kernel woudlnt work (i assume it messes with the headers and therefore the IBM cant boot the image). My rootfs is a gentoo stage3 tarball with the latest portage (on how to install gentoo see the gentoo handbook and for tiny systems gentoo wiki or this). Additional packets i installed are e.g. lighttpd, php, sqlite, sshd, dhcpd, screen, cron, pciutils usbutils, …

Here are some files you might want to have a look at:

Output of:
uname -a
cat /proc/cpuinfo

As you might have noticed i added 128MB of PC133 SD-Ram (168pin) to the internal 32MB. There is a normal slot, so opening the device is highly recommended! Furthermore i plugged in a 1GB USB-Stick to one usbports and made it /home. /data is the external harddrive which also provides a little swapspace (barely used).

To sum things up, im very happy with this stylish little box running gentoo at a decent speed (i was to lazy to crosscompile the packages, i think it took about 50h to compile everything but i had the time. Just remember to emerge screen first!), providing all the services i need. The powerconsumption is ok, my router, modem, external harddrive and server together need about 38W. For this price (15Eur at ebay) a really good setup.

Other links:

I managed to get a 2.6.31 Kernel booting, check my new post here